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 |