Medication | Usual adult dose | Onset of action | Side effects |
Bulk-forming laxatives* | |||
Psyllium | Up to 1 tablespoon (≅3.5 grams fiber) 3 times per day | 12 to 72 h | Impaction above strictures, fluid overload, gas and bloating |
Methylcellulose | Up to 1 tablespoon (≅2 grams fiber) or 4 caplets (500 mg fiber per caplet) 3 times per day | 12 to 72 h | |
Polycarbophil | 2 to 4 tabs (500 mg fiber per tab) per day | 24 to 48 h | |
Wheat dextrin¶ | 1 to 3 caplets (1 gram fiber per caplet) or 2 teaspoonsful (1.5 gram fiber per teaspoon) up to 3 times per daily | 24 to 48 h | |
Surfactants (softeners) | |||
Docusate sodium | 100 mg 2 times per day | 24 to 72 hours | Well tolerated, but less effective than other agents. Use lower dose if administered with another laxative. Contact dermatitis reported. |
Docusate calcium | 240 mg 1 time per day | 24 to 72 hours | |
Osmotic agents | |||
Polyethylene glycol (macrogol) | 8.5 to 34 grams in 240 mL (8 ounces) liquids | 1 to 4 days | Nausea, bloating, cramping |
Lactulose | 10 to 20 grams (15 to 30 mL) every other day. May increase up to 2 times per day. | 24 to 48 hours | Abdominal bloating, flatulence |
Sorbitol | 30 grams (120 mL of 25% solution) 1 time per day | 24 to 48 hours | Abdominal bloating, flatulence |
Glycerin (glycerol) | One suppository (2 or 3 grams) per rectum for 15 minutes 1 time per day | 15 to 60 minutes | Rectal irritation |
Magnesium sulfate | 2 to 4 level teaspoons (approximately 10 to 20 grams) of granules dissolved in 8 ounces (240 mL) of water; may repeat in 4 hours. Do not exceed 2 doses per day. | 0.5 to 3 hours | Watery stools and urgency; caution in renal insufficiency (magnesium toxicity) |
Magnesium citrate | 200 mL (11.6 grams) 1 time per day | 0.5 to 3 hours | |
Stimulant laxatives | |||
Bisacodyl | 10 to 30 mg as enteric coated tabs 1 time per day | 6 to 10 hours | Gastric irritation |
10 mg suppository per rectum 1 time per day | 15 to 60 minutes | Rectal irritation | |
Senna | 2 to 4 tabs (8.6 mg sennosides per tab) or 1 to 2 tabs (15 mg sennosides per tab) as a single daily dose or divided twice daily | 6 to 12 hours | Melanosis coli |
Other | |||
Lubiprostone | 24 micrograms 2 times per day | 24 to 48 hours | Nausea, diarrhea |
Linaclotide | 145 micrograms 1 time per day | 12 to 24 hours | Diarrhea, bloating |
Plecanatide | 3 mg 1 time per day | 12 to 24 hours | Diarrhea |
Prucalopride | 2 mg per day | 6 to 12 hours | Nausea, headache, diarrhea |
* Initiate at one-half or less of dose shown and gradually increase as needed to minimize gas and bloating. Administer with 180 to 360 mL (6 to 12 ounces) water or fruit juice. Do not administer within 1 hour of other medications. Fiber content per dose may vary. Consult individual product label.
¶ US trade name Benefiber.Courtesy of Arnold Wald, MD.
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