Over-the-Counter (OTC) Laxatives for Constipation

Bulk-forming laxatives

Ispaghula husk, methylcellulose and sterculia

2-3 days

Increase faecal mass which stimulates peristalsis

Flatulence and abdominal distension

Drink adequate amounts of fluid to avoid intestinal obstruction

Do not take before bedtime

Stimulant laxatives

Bisacodyl, docusate sodium, glycerol, senna, and sodium picosulfate

6-12 hours

Suppositories 15-60 minutes

Increase intestinal motility by directly stimulating the colonic nerves

Docusate sodium acts both as a stimulant and as a softening agent

Glycerol acts as a rectal stimulant

Abdominal pain

Take at bedtime to produce an effect the next morning

Faecal softeners

Liquid paraffin (should not be recommended – see adverse / side effects) and docusate sodium

1-2 days

Docusate sodium acts as a faecal softener by lowering the surface tension which allows fluid to penetrate the stool, thereby softening the stool. Docusate sodium also has mild stimulant action

Liquid Paraffin: anal seepage and irritation, granulomatous reactions caused by absorption of small quantities of liquid paraffin, lipoid pneumonia, and malabsorption of fat-soluble vitamins

Osmotic laxatives

Lactulose, macrogols and magnesium salts

1-3 days

Magnesium salts – few hours

Retain fluid in the bowel by osmosis or alter the pattern of water distribution in the faeces

Flatulence, bloating, abdominal cramps

Drink adequate amounts of fluid