A laxative is a medication that increases bowel function. There are four main classes of laxatives:
- osmotic laxatives,
- stimulant laxatives, and
Because most current pharmacological treatments are aimed at improving only one IBS symptom, it is often necessary to use a combination of therapies for adequate treatment.
Fiber – Dietary fiber should be the first laxative treatment method tried. To minimize possible discomfort, gradually increase your dietary fiber intake to approximately 20 to 25 grams per day over several weeks. Initially, foods rich in dietary fiber should be increased. If results from this therapy are disappointing, then commercially packaged fiber supplements should be used. Read More About Dietary Fiber
Osmotic laxatives are poorly absorbed compounds that cause an influx of water into the small intestine and colon, thereby increasing stool bulk. When the recommended dosage is used, it takes approximately 1 to 2 days for osmotic laxatives to take effect. Polyethylene glycol produces less intestinal gas and causes less abdominal bloating and flatulence than other osmotic laxatives.
Stimulant laxatives should be used sparingly and only when osmotic laxatives have been ineffective. They have a direct stimulating effect on the network of nerves in the large intestine and reduce absorption of water and electrolytes from gastrointestinal contents. Stimulant laxatives take effect within hours of ingestion. Stimulant laxatives should be used with caution since they can cause dehydration and electrolyte disturbances.
Emollients act as stool softeners (e.g., Colace and Surfak). They provide moisture to the stool making it easier to pass.
Source: Lembo T and Rink R. Current Pharmacologic Treatments of Irritable Bowel Syndrome. IFFGD Fact Sheet No. 168.