Illness, changes in diet or a poor diet, and certain medications can lead to constipation. Difficulty defecating can be painful. Some people experience constipation rarely, while others have chronic constipation. Laxatives can alleviate constipation, but the right laxative depends on the reasons for your constipation and other health factors. You can buy most laxatives over the counter, though some formulas are sold by prescription only.

Stimulant Laxatives

Stimulant laxatives work by causing the muscles of the intestines to contract. These powerful laxatives work quickly and are sometimes used prior to a colonoscopy to clean out the intestines. Side effects include pain and cramping. You should only use stimulant laxatives occasionally. Use them if bulk-forming laxatives or dietary changes don't work. Using stimulants too often can lead to dependence and problems with chronic constipation. Also, too-frequent use may result in dehydration or an electrolyte imbalance.

Osmotic and Lubricant Laxatives

Osmotic laxatives add water to your stool to make it softer. They work quickly and are another popular choice for colonoscopy prep. If you use these kinds of laxatives too often, you risk dehydration and electrolyte imbalance. Lubricant laxatives are oils that coat the stool. These, too, work quickly -- so quickly you might have trouble making it to the restroom in time.

Bulk-Forming Laxatives

Bulk-forming laxatives add bulk in the form of fiber to soften stool and make it easier to pass. These laxatives take about 12 hours to work. The fiber in these laxatives is safe and made from ingredients such as psyllium husks or cellulose. You can also use natural fiber such as flax seeds, or add more fresh vegetables or high-fiber cereals to your diet. Often, increasing fiber in your diet is enough to relieve constipation. Adult women should aim for 25 grams of fiber daily to age 50 and 21 grams after 50, while men need 38 grams to age 50 and 30 grams after age 50. Bulk-forming laxatives are a good choice for people with chronic constipation, since they don't lead to dependency and add healthy fiber to the diet.

Precautions

When taking laxatives, drink plenty of water. This helps you stay hydrated and also makes bulk-forming and osmotic laxatives work better. Don't take laxatives more often than recommended on the label. If a laxative doesn't relieve your constipation in a few days, see your doctor. Don't rely on laxatives for weight loss.