Upper respiratory tract conditions: Oral: Note: Refer to specific product labeling for detailed information.
Liquid:
Diphenhydramine 6.25 mg and phenylephrine 2.5 mg per 5 mL: 20 mL every 4 hours as needed (maximum: 6 doses/24 hours).
Diphenhydramine 12.5 mg and phenylephrine 5 mg per 5 mL: 10 mL every 4 hours as needed (maximum: 6 doses/24 hours).
Tablets: Diphenhydramine 25 mg and phenylephrine 10 mg per tablet: 1 tablet every 4 hours as needed (maximum: 6 doses/24 hours).
Avoid use (Ref).
(For additional information see "Diphenhydramine and phenylephrine: Pediatric drug information")
Note: Multiple concentrations of oral liquid formulations exist; close attention must be paid to the concentration when ordering or administering. Safety and efficacy for the use of cough and cold products in infants and young children is limited; the AAP warns against the use of these products for respiratory illnesses in infants and young children; the FDA does not recommend OTC use in infants and children <2 years of age due to the risk of serious and life-threatening adverse effects (including death) and recommends to use with caution in pediatric patients ≥2 years of age (Ref).
Allergic rhinitis, nasal congestion:
Diphenhydramine 6.25 mg and phenylephrine 2.5 mg per 5 mL:
Children 6 to 11 years: Oral: 10 mL every 4 hours as needed; maximum dose: 60 mL/24 hours.
Children ≥12 years and Adolescents: Oral: 20 mL every 4 hours as needed; maximum dose: 120 mL/24 hours.
Diphenhydramine 12.5 mg and phenylephrine 5 mg per 5 mL:
Children 6 to 11 years: Oral: 5 mL every 4 hours as needed; maximum dose: 30 mL/24 hours.
Children ≥12 years and Adolescents: Oral: 10 mL every 4 hours as needed; maximum dose: 60 mL/24 hours.
There are no dosage adjustments provided in the manufacturer's labeling.
There are no dosage adjustments provided in the manufacturer's labeling.
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Frequency not defined.
Cardiovascular: Chest tightness, extrasystoles, hypotension, palpitations, tachycardia
Central nervous system: Ataxia, chills, confusion, dizziness, drowsiness, euphoria, excitement, fatigue, headache, insomnia, irritability, nervousness, neuritis, paresthesia, restlessness, sedation, seizure, vertigo
Dermatologic: Diaphoresis, skin photosensitivity, skin rash, urticaria
Gastrointestinal: Anorexia, constipation, diarrhea, dry mucous membranes, epigastric distress, nausea, vomiting, xerostomia
Genitourinary: Dysuria, early menses, urinary retention
Hematologic & oncologic: Agranulocytosis, hemolytic anemia, thrombocytopenia
Hypersensitivity: Anaphylaxis
Neuromuscular & skeletal: Tremor
Ophthalmic: Blurred vision, diplopia
Otic: Labyrinthitis, tinnitus
Renal: Polyuria
Respiratory: Constriction of the pharynx, nasal congestion, thickening of bronchial secretions, wheezing
OTC labeling: When used for self-medication, do not use to sedate a child, with or within 14 days of stopping monoamine oxidase inhibitor therapy, or concurrently with any other product containing diphenhydramine (including topical).
Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.
Concerns related to adverse effects:
• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).
Special populations:
• Pediatric: Antihistamines may cause excitation in young children. Toxicity (overdose) in pediatric patients may result in hallucinations, convulsions, or death; neonates and young children are highly sensitive to depressive effects of diphenhydramine.
Dosage form specific issues:
• Benzyl alcohol and derivatives: Some dosage forms may contain benzyl alcohol and/or sodium benzoate/benzoic acid; benzoic acid (benzoate) is a metabolite of benzyl alcohol; large amounts of benzyl alcohol (≥99 mg/kg/day) have been associated with a potentially fatal toxicity ("gasping syndrome") in neonates; the "gasping syndrome" consists of metabolic acidosis, respiratory distress, gasping respirations, CNS dysfunction (including convulsions, intracranial hemorrhage), hypotension and cardiovascular collapse (AAP ["Inactive" 1997]; CDC 1982); some data suggests that benzoate displaces bilirubin from protein binding sites (Ahlfors 2001); avoid or use dosage forms containing benzyl alcohol and/or benzyl alcohol derivative with caution in neonates. See manufacturer's labeling.
• Phenylalanine: Some products may contain aspartame, which is metabolized to phenylalanine and must be avoided (or used with caution) in patients with phenylketonuria.
• Propylene glycol: Some dosage forms may contain propylene glycol; large amounts are potentially toxic and have been associated with hyperosmolality, lactic acidosis, seizures, and respiratory depression; use caution (AAP ["Inactive" 1997]; Zar 2007).
Other warnings/precautions:
• Self-medication (OTC use): When used for self-medication (OTC), notify health care provider prior to use if you have breathing problems (eg, chronic bronchitis, emphysema), persistent or chronic cough (such as occurs with asthma or smoking), productive cough (eg, excessive amounts of phlegm), diabetes, glaucoma, heart disease, high BP, thyroid disease, difficultly in urination due to enlargement of the prostate gland, or are currently taking sedatives, tranquilizers, or other oral nasal decongestants or stimulants. Discontinue use and notify health care provider if symptoms do not improve within 7 days or are accompanied by fever, cough lasts ≥7 days, comes back, or is accompanied by fever, rash, or persistent headache, or if nervousness, dizziness, or sleeplessness occur.
Safety and efficacy for the use of cough and cold products in pediatric patients <4 years of age is limited; the AAP warns against the use of these products for respiratory illnesses in young children. Serious adverse effects, including death, have been reported. Many of these products contain multiple active ingredients, increasing the risk of accidental overdose when used with other products. The FDA does not recommend OTC uses for these products in pediatric patients <2 years of age and recommends to use with caution in pediatric patients ≥2 years of age. Health care providers are reminded to ask caregivers about the use of OTC cough and cold products in order to avoid exposure to multiple medications containing the same ingredient (AAP 2018; CDC 2007; FDA 2017; FDA 2018). Toxicity (overdosage) in pediatric patients can result in hallucinations, convulsions, or death. Antihistamines should not be used to make an infant or child sleepy. Multiple concentrations of oral liquid formulations exist; close attention must be paid to the concentration when ordering or administering.
Some dosage forms may contain propylene glycol; in neonates, large amounts of propylene glycol delivered orally, intravenously (eg, >3,000 mg/day), or topically have been associated with potentially fatal toxicities which can include metabolic acidosis, seizures, renal failure, and CNS depression; toxicities have also been reported in children and adults including hyperosmolality, lactic acidosis, seizures, and respiratory depression; use caution (AAP 1997; Shehab 2009).
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Liquid, Oral:
Dimetapp Night Cold/Congestion: Diphenhydramine hydrochloride 6.25 mg and phenylephrine hydrochloride 2.5 mg per 5 mL (118 mL) [contains fd&c blue #1 (brilliant blue), fd&c red #40 (allura red ac dye), propylene glycol, sodium benzoate]
Solution, Oral:
Benadryl Allergy Childrens: Diphenhydramine hydrochloride 12.5 mg and phenylephrine hydrochloride 5 mg per 5 mL (118 mL) [alcohol free, sugar free; contains disodium edta, fd&c blue #1 (brilliant blue), fd&c red #40 (allura red ac dye), sodium benzoate; grape flavor]
Syrup, Oral:
Triaminic Night Time Cold/Cgh: Diphenhydramine hydrochloride 6.25 mg and phenylephrine hydrochloride 2.5 mg per 5 mL (118 mL [DSC]) [contains edetate (edta) disodium, fd&c blue #1 (brilliant blue), fd&c red #40 (allura red ac dye), propylene glycol, sodium benzoate; grape flavor]
Tablet, Oral:
Benadryl Allergy Con Ultratabs: Diphenhydramine hydrochloride 25 mg and phenylephrine hydrochloride 10 mg [contains fd&c blue #1 (brill blue) aluminum lake]
Sudafed PE Sinus Cong Day/Nght: Diphenhydramine hydrochloride 25 mg/phenylephrine hydrochloride 10 mg (12s) & phenylephrine hydrochloride 10 mg (18s) [pseudoephedrine free; contains fd&c blue #1 (brill blue) aluminum lake, fd&c red #40(allura red ac)aluminum lake, fd&c yellow #6(sunset yellow)alumin lake, quinoline (d&c yellow #10) aluminum lake]
No
Liquid (Dimetapp Night Cold/Congestion Oral)
6.25-2.5 mg/5 mL (per mL): $0.04
Solution (Benadryl Allergy Childrens Oral)
12.5-5 mg/5 mL (per mL): $0.06
Tablets (Benadryl Allergy Con Ultratabs Oral)
25-10 mg (per each): $0.30
Tablets (Sudafed PE Sinus Cong Day/Nght Oral)
25-10 & 10 mg (per each): $0.34
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
Administer liquid formulations using the provided dosing cup. Do not use any other dosing device.
Oral: Administer without regard to food. Administer with an accurate measuring device; do not use a household teaspoon (overdosage may occur).
Upper respiratory tract conditions: Temporary relief of symptoms (nasal congestion/pressure, runny nose, sneezing, itchy nose or throat, itchy/watery eyes) associated with the common cold, allergic rhinitis (hay fever), and other upper respiratory tract conditions.
Benadryl-D brand name for diphenhydramine and phenylephrine [US] may be confused with Benadryl brand name for cetirizine [Great Britain, Phillipines] and Benadryl brand name for acrivastine and pseudoephedrine [Great Britain]
Diphenhydramine (oral), a first-generation antihistamine, is identified in the Beers Criteria as a potentially inappropriate medication to be avoided in patients 65 years and older (independent of diagnosis or condition) due to its potent anticholinergic properties resulting in increased risk of confusion, dry mouth, constipation, and other anticholinergic effects or toxicity; use should also be avoided due to reduced clearance with advanced age and tolerance associated with use as a hypnotic. Exposure to concurrent anticholinergic drugs also increases risk of falls, delirium, and dementia; consider total anticholinergic burden when conducting medication reviews. However, use of diphenhydramine may be appropriate in certain situations such as acute treatment of severe allergic reaction (Beers Criteria [AGS 2023).
Refer to individual components.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Acetaminophen: May increase the serum concentration of Phenylephrine (Systemic). Risk C: Monitor therapy
Acetylcholinesterase Inhibitors: May diminish the therapeutic effect of Agents with Clinically Relevant Anticholinergic Effects. Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Acetylcholinesterase Inhibitors. Risk C: Monitor therapy
Aclidinium: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Agents with Clinically Relevant Anticholinergic Effects: May enhance the adverse/toxic effect of other Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Risk C: Monitor therapy
Alizapride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Alpha1-Blockers: May diminish the vasoconstricting effect of Phenylephrine (Systemic). Risk C: Monitor therapy
Amantadine: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Amezinium: Antihistamines may enhance the stimulatory effect of Amezinium. Risk C: Monitor therapy
Atomoxetine: May enhance the hypertensive effect of Sympathomimetics. Atomoxetine may enhance the tachycardic effect of Sympathomimetics. Risk C: Monitor therapy
Atropine (Systemic): May enhance the hypertensive effect of Alpha1-Agonists. Risk C: Monitor therapy
Azelastine (Nasal): May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Benperidol: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Benperidol. Risk C: Monitor therapy
Benzylpenicilloyl Polylysine: Antihistamines may diminish the diagnostic effect of Benzylpenicilloyl Polylysine. Management: Suspend systemic H1 antagonists for benzylpenicilloyl-polylysine skin testing and delay testing until systemic antihistaminic effects have dissipated. A histamine skin test may be used to assess persistent antihistaminic effects. Risk D: Consider therapy modification
Benzylpenicilloyl Polylysine: Alpha1-Agonists may diminish the diagnostic effect of Benzylpenicilloyl Polylysine. Management: Consider delaying skin testing until alpha1-agonists are no longer required, or use of a histamine skin test as a positive control to assess a patient's ability to mount a wheal and flare response. Risk D: Consider therapy modification
Betahistine: Antihistamines may diminish the therapeutic effect of Betahistine. Betahistine may diminish the therapeutic effect of Antihistamines. Risk C: Monitor therapy
Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Management: Use caution if coadministering blonanserin and CNS depressants; dose reduction of the other CNS depressant may be required. Strong CNS depressants should not be coadministered with blonanserin. Risk D: Consider therapy modification
Botulinum Toxin-Containing Products: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Brexanolone: CNS Depressants may enhance the CNS depressant effect of Brexanolone. Risk C: Monitor therapy
Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Bromocriptine: May enhance the hypertensive effect of Alpha1-Agonists. Management: Consider alternatives to this combination when possible. If combined, monitor for hypertension and tachycardia, and do not coadminister these agents for more than 10 days. Risk D: Consider therapy modification
Bromopride: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Bromperidol: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine at lower doses in patients already receiving CNS depressants. Risk D: Consider therapy modification
Cannabinoid-Containing Products: May enhance the tachycardic effect of Sympathomimetics. Risk C: Monitor therapy
Cannabinoid-Containing Products: Agents with Clinically Relevant Anticholinergic Effects may enhance the tachycardic effect of Cannabinoid-Containing Products. Risk C: Monitor therapy
Cannabinoid-Containing Products: CNS Depressants may enhance the CNS depressant effect of Cannabinoid-Containing Products. Risk C: Monitor therapy
Chloral Betaine: May enhance the adverse/toxic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Chlormethiazole: May enhance the CNS depressant effect of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. Risk D: Consider therapy modification
Chloroprocaine (Systemic): May enhance the hypotensive effect of Phenylephrine (Systemic). Risk C: Monitor therapy
Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Risk C: Monitor therapy
Chlorprothixene: Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Chlorprothixene. Risk C: Monitor therapy
Cimetropium: Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Cimetropium. Risk X: Avoid combination
CloZAPine: Agents with Clinically Relevant Anticholinergic Effects may enhance the constipating effect of CloZAPine. Management: Consider alternatives to this combination whenever possible. If combined, monitor closely for signs and symptoms of gastrointestinal hypomotility and consider prophylactic laxative treatment. Risk D: Consider therapy modification
CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Risk C: Monitor therapy
Cocaine (Topical): May enhance the hypertensive effect of Sympathomimetics. Management: Consider alternatives to use of this combination when possible. Monitor closely for substantially increased blood pressure or heart rate and for any evidence of myocardial ischemia with concurrent use. Risk D: Consider therapy modification
Daridorexant: May enhance the CNS depressant effect of CNS Depressants. Management: Dose reduction of daridorexant and/or any other CNS depressant may be necessary. Use of daridorexant with alcohol is not recommended, and the use of daridorexant with any other drug to treat insomnia is not recommended. Risk D: Consider therapy modification
DexmedeTOMIDine: CNS Depressants may enhance the CNS depressant effect of DexmedeTOMIDine. Management: Monitor for increased CNS depression during coadministration of dexmedetomidine and CNS depressants, and consider dose reductions of either agent to avoid excessive CNS depression. Risk D: Consider therapy modification
Difelikefalin: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Dimethindene (Systemic): Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Dimethindene (Systemic). Risk C: Monitor therapy
Dimethindene (Topical): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Disulfiram: May enhance the adverse/toxic effect of Products Containing Ethanol. Management: Do not use disulfiram with dosage forms that contain ethanol. Risk X: Avoid combination
Doxofylline: Sympathomimetics may enhance the adverse/toxic effect of Doxofylline. Risk C: Monitor therapy
Doxylamine: CNS Depressants may enhance the CNS depressant effect of Doxylamine. Risk C: Monitor therapy
DroPERidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Risk D: Consider therapy modification
Eluxadoline: Agents with Clinically Relevant Anticholinergic Effects may enhance the constipating effect of Eluxadoline. Risk X: Avoid combination
Ergot Derivatives (Vasoconstrictive CYP3A4 Substrates): May enhance the vasoconstricting effect of Alpha1-Agonists. Risk X: Avoid combination
Esketamine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Flunarizine: CNS Depressants may enhance the CNS depressant effect of Flunarizine. Risk X: Avoid combination
Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Management: Reduce the dose of CNS depressants when combined with flunitrazepam and monitor patients for evidence of CNS depression (eg, sedation, respiratory depression). Use non-CNS depressant alternatives when available. Risk D: Consider therapy modification
Gastrointestinal Agents (Prokinetic): Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Gastrointestinal Agents (Prokinetic). Risk C: Monitor therapy
Glucagon: Agents with Clinically Relevant Anticholinergic Effects may enhance the adverse/toxic effect of Glucagon. Specifically, the risk of gastrointestinal adverse effects may be increased. Risk C: Monitor therapy
Glycopyrrolate (Oral Inhalation): Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Glycopyrrolate (Oral Inhalation). Risk X: Avoid combination
Glycopyrronium (Topical): May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Guanethidine: May enhance the arrhythmogenic effect of Sympathomimetics. Guanethidine may enhance the hypertensive effect of Sympathomimetics. Risk C: Monitor therapy
Haloperidol: QT-prolonging Agents (Indeterminate Risk - Caution) may enhance the QTc-prolonging effect of Haloperidol. Risk C: Monitor therapy
Hyaluronidase: May enhance the vasoconstricting effect of Phenylephrine (Systemic). Management: Do not use hyaluronidase to enhance the dispersion or absorption of phenylephrine. Use of hyaluronidase for other purposes in patients receiving phenylephrine may be considered as clinically indicated. Risk D: Consider therapy modification
HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Management: Consider a decrease in the CNS depressant dose, as appropriate, when used together with hydroxyzine. Increase monitoring of signs/symptoms of CNS depression in any patient receiving hydroxyzine together with another CNS depressant. Risk D: Consider therapy modification
Iobenguane Radiopharmaceutical Products: Alpha1-Agonists may diminish the therapeutic effect of Iobenguane Radiopharmaceutical Products. Management: Discontinue all drugs that may inhibit or interfere with catecholamine transport or uptake for at least 5 biological half-lives before iobenguane administration. Do not administer these drugs until at least 7 days after each iobenguane dose. Risk X: Avoid combination
Ipratropium (Nasal): May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Ipratropium (Oral Inhalation): May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Isoproterenol: DiphenhydrAMINE (Systemic) may enhance the therapeutic effect of Isoproterenol. Risk C: Monitor therapy
Itopride: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Itopride. Risk C: Monitor therapy
Ixabepilone: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Kava Kava: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Kratom: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Kratom: May enhance the adverse/toxic effect of Sympathomimetics. Risk X: Avoid combination
Lemborexant: May enhance the CNS depressant effect of CNS Depressants. Management: Dosage adjustments of lemborexant and of concomitant CNS depressants may be necessary when administered together because of potentially additive CNS depressant effects. Close monitoring for CNS depressant effects is necessary. Risk D: Consider therapy modification
Levosulpiride: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Levosulpiride. Risk X: Avoid combination
Levothyroxine: May enhance the adverse/toxic effect of Sympathomimetics. Specifically, the risk of coronary insufficiency may be increased in patients with coronary artery disease. Levothyroxine may enhance the therapeutic effect of Sympathomimetics. Sympathomimetics may enhance the therapeutic effect of Levothyroxine. Risk C: Monitor therapy
Linezolid: May enhance the hypertensive effect of Sympathomimetics. Management: Consider initial dose reductions of sympathomimetic agents, and closely monitor for enhanced blood pressure elevations, in patients receiving linezolid. Risk D: Consider therapy modification
Lisuride: May enhance the hypertensive effect of Alpha1-Agonists. Risk X: Avoid combination
Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Loxapine: CNS Depressants may enhance the CNS depressant effect of Loxapine. Risk D: Consider therapy modification
Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Methotrimeprazine: Products Containing Ethanol may enhance the adverse/toxic effect of Methotrimeprazine. Specifically, a disulfiram-like reaction may occur and CNS depressant effects may be increased. Management: Avoid products containing alcohol in patients treated with methotrimeprazine. Risk X: Avoid combination
Metoclopramide: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Risk C: Monitor therapy
Mianserin: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Minocycline (Systemic): May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Mirabegron: Agents with Clinically Relevant Anticholinergic Effects may enhance the adverse/toxic effect of Mirabegron. Risk C: Monitor therapy
Monoamine Oxidase Inhibitors: May enhance the hypertensive effect of Alpha1-Agonists. While linezolid is expected to interact via this mechanism, management recommendations differ from other monoamine oxidase inhibitors. Refer to linezolid specific monographs for details. Risk X: Avoid combination
Nabilone: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Nitroglycerin: Agents with Clinically Relevant Anticholinergic Effects may decrease the absorption of Nitroglycerin. Specifically, anticholinergic agents may decrease the dissolution of sublingual nitroglycerin tablets, possibly impairing or slowing nitroglycerin absorption. Risk C: Monitor therapy
Olopatadine (Nasal): May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Opioid Agonists: CNS Depressants may enhance the CNS depressant effect of Opioid Agonists. Management: Avoid concomitant use of opioid agonists and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider therapy modification
Ornidazole: May enhance the adverse/toxic effect of Products Containing Ethanol. Specifically, a disulfiram-like reaction may occur. Risk X: Avoid combination
Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Risk X: Avoid combination
Oxatomide: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Oxomemazine: May enhance the CNS depressant effect of CNS Depressants. Risk X: Avoid combination
Oxybate Salt Products: CNS Depressants may enhance the CNS depressant effect of Oxybate Salt Products. Management: Consider alternatives to this combination when possible. If combined, dose reduction or discontinuation of one or more CNS depressants (including the oxybate salt product) should be considered. Interrupt oxybate salt treatment during short-term opioid use Risk D: Consider therapy modification
OxyCODONE: CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: Avoid concomitant use of oxycodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Risk D: Consider therapy modification
Ozanimod: May enhance the hypertensive effect of Sympathomimetics. Risk C: Monitor therapy
Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Risk X: Avoid combination
Perampanel: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Pergolide: May enhance the hypertensive effect of Alpha1-Agonists. Risk C: Monitor therapy
Piribedil: CNS Depressants may enhance the CNS depressant effect of Piribedil. Risk C: Monitor therapy
Pitolisant: Antihistamines may diminish the therapeutic effect of Pitolisant. Risk X: Avoid combination
Potassium Chloride: Agents with Clinically Relevant Anticholinergic Effects may enhance the ulcerogenic effect of Potassium Chloride. Management: Patients on drugs with substantial anticholinergic effects should avoid using any solid oral dosage form of potassium chloride. Risk X: Avoid combination
Potassium Citrate: Agents with Clinically Relevant Anticholinergic Effects may enhance the ulcerogenic effect of Potassium Citrate. Management: Patients on drugs with substantial anticholinergic effects should avoid using any solid oral dosage form of potassium citrate. Risk X: Avoid combination
Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Risk C: Monitor therapy
Pramlintide: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. These effects are specific to the GI tract. Risk X: Avoid combination
Procarbazine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Propacetamol: May increase the serum concentration of Phenylephrine (Systemic). Management: Monitor patients closely for increased side effects of phenylephrine if propacetamol is used concomitantly. Patients with underlying blood pressure issues or arrhythmias may need closer monitoring and may warrant consideration of alternative therapies. Risk C: Monitor therapy
QT-prolonging Agents (Highest Risk): QT-prolonging Agents (Indeterminate Risk - Caution) may enhance the QTc-prolonging effect of QT-prolonging Agents (Highest Risk). Management: Monitor for QTc interval prolongation and ventricular arrhythmias when these agents are combined. Patients with additional risk factors for QTc prolongation may be at even higher risk. Risk C: Monitor therapy
QuiNIDine: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor therapy
Ramosetron: Agents with Clinically Relevant Anticholinergic Effects may enhance the constipating effect of Ramosetron. Risk C: Monitor therapy
Revefenacin: Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Revefenacin. Risk X: Avoid combination
Rivastigmine: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Rivastigmine. Rivastigmine may diminish the therapeutic effect of Agents with Clinically Relevant Anticholinergic Effects. Management: Use of rivastigmine with an anticholinergic agent is not recommended unless clinically necessary. If the combination is necessary, monitor for reduced anticholinergic effects. Risk D: Consider therapy modification
Ropeginterferon Alfa-2b: CNS Depressants may enhance the adverse/toxic effect of Ropeginterferon Alfa-2b. Specifically, the risk of neuropsychiatric adverse effects may be increased. Management: Avoid coadministration of ropeginterferon alfa-2b and other CNS depressants. If this combination cannot be avoided, monitor patients for neuropsychiatric adverse effects (eg, depression, suicidal ideation, aggression, mania). Risk D: Consider therapy modification
ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Risk C: Monitor therapy
Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Risk C: Monitor therapy
Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Risk C: Monitor therapy
Secnidazole: Products Containing Ethanol may enhance the adverse/toxic effect of Secnidazole. Risk X: Avoid combination
Secretin: Agents with Clinically Relevant Anticholinergic Effects may diminish the therapeutic effect of Secretin. Management: Avoid concomitant use of anticholinergic agents and secretin. Discontinue anticholinergic agents at least 5 half-lives prior to administration of secretin. Risk D: Consider therapy modification
Solriamfetol: Sympathomimetics may enhance the hypertensive effect of Solriamfetol. Sympathomimetics may enhance the tachycardic effect of Solriamfetol. Risk C: Monitor therapy
Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Risk D: Consider therapy modification
Sympathomimetics: May enhance the adverse/toxic effect of other Sympathomimetics. Risk C: Monitor therapy
Tedizolid: May enhance the hypertensive effect of Sympathomimetics. Tedizolid may enhance the tachycardic effect of Sympathomimetics. Risk C: Monitor therapy
Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Risk X: Avoid combination
Thiazide and Thiazide-Like Diuretics: Agents with Clinically Relevant Anticholinergic Effects may increase the serum concentration of Thiazide and Thiazide-Like Diuretics. Risk C: Monitor therapy
Thioridazine: CYP2D6 Inhibitors (Weak) may increase the serum concentration of Thioridazine. Management: Consider avoiding concomitant use of thioridazine and weak CYP2D6 inhibitors. If combined, monitor closely for QTc interval prolongation and arrhythmias. Some weak CYP2D6 inhibitors list use with thioridazine as a contraindication. Risk D: Consider therapy modification
Tiotropium: Agents with Clinically Relevant Anticholinergic Effects may enhance the anticholinergic effect of Tiotropium. Risk X: Avoid combination
Topiramate: Agents with Clinically Relevant Anticholinergic Effects may enhance the adverse/toxic effect of Topiramate. Risk C: Monitor therapy
Tranylcypromine: May enhance the anticholinergic effect of Antihistamines, First Generation. Risk X: Avoid combination
Tricyclic Antidepressants: May enhance the therapeutic effect of Alpha1-Agonists. Tricyclic Antidepressants may diminish the therapeutic effect of Alpha1-Agonists. Risk C: Monitor therapy
Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Umeclidinium: May enhance the anticholinergic effect of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid combination
Valerian: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Risk D: Consider therapy modification
Zuranolone: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to the use of zuranolone with other CNS depressants or alcohol. If combined, consider a zuranolone dose reduction and monitor patients closely for increased CNS depressant effects. Risk D: Consider therapy modification
Refer to individual monographs.
Refer to individual monographs.
Some products may contain phenylalanine and/or sodium.
Diphenhydramine is an H1-receptor antagonist.
Phenylephrine is a potent, direct-acting alpha-adrenergic stimulator.
See individual agents.
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