Over-the-counter laxatives for constipation: Use with caution

Laxatives can help relieve and prevent constipation. But not all laxatives are safe for long-term use. Overuse of certain laxatives can lead to dependency and decreased bowel function. By Mayo Clinic Staff

If you've ever experienced the discomfort of constipation — perhaps while traveling or after a change in your diet — you may have considered over-the-counter laxatives. Over-the-counter laxatives come in many different forms — liquids, tablets, wafers, gums, or powders that you dissolve in water. You take rectal laxatives in the form of suppositories or enemas.

How often you have a bowel movement varies, but a "normal" frequency ranges from as many as three bowel movements a day to about three a week. Your body ordinarily needs no help to have bowel movements. But a poor diet, physical inactivity, pregnancy, illness or some medications can disrupt normal bowel function and cause constipation.

Before trying laxatives

Before turning to laxatives for relief, try these lifestyle changes to help manage occasional irregularity:

  • Eat fiber-rich foods, such as wheat bran, fresh fruits and vegetables, and oats.
  • Drink plenty of fluids daily.
  • Exercise regularly.

Lifestyle and dietary improvements relieve constipation for many people, but if problems continue despite these changes, your next choice may be a mild laxative.

How laxatives relieve constipation

Laxatives work in different ways, and the effectiveness of each laxative type varies from person to person. In general, bulk-forming laxatives, which are also referred to as fiber supplements, are the gentlest on your body and safe to use long term. Metamucil and Citrucel fall into this category. Stimulant laxatives, such as Ex-Lax and Senokot, are the harshest and shouldn't be used long term.

Following are some examples of common types of laxatives. Other types also exist. Even though many laxatives are available over-the-counter, it's best to talk to your doctor about laxative use and which kind may be best for you.

Type of laxative
(brand examples)
How they workSide effects

Oral osmotics (Phillips' Milk of Magnesia, Miralax)

Draw water into colon from surrounding body tissues to allow easier passage of stool Bloating, cramping, diarrhea, nausea, gas, increased thirst
Oral bulk formers (Benefiber, Citrucel, Fiber Choice, Metamucil) Absorb water to form soft, bulky stool, prompting normal contraction of intestinal muscles Bloating, gas, cramping, choking or increased constipation if not taken with enough water
Oral stool softeners (Colace, Kaopectate) Add moisture to stool to allow strain-free bowel movements Throat irritation, cramping
Oral stimulants (Ex-lax, Senokot) Trigger rhythmic contractions of intestinal muscles to eliminate stool Belching, cramping, diarrhea, nausea, urine discoloration
Rectal stimulants (Bisacodyl, Pedia-Lax, Dulcolax) Trigger rhythmic contractions of intestinal muscles to eliminate stool Rectal irritation, stomach discomfort, cramping

Oral laxatives may interfere with your body's absorption of some medications and food nutrients. Rectal laxatives do not have this effect. Also, some oral and rectal laxatives can lead to an electrolyte imbalance, especially after prolonged use. Electrolytes, which include calcium, chloride, potassium, magnesium and sodium, regulate muscle contraction, heart rhythm, nerve function, fluid balance and other body functions. An electrolyte imbalance can cause abnormal heart rhythms, weakness, confusion and seizures.

Apr. 23, 2011 See more In-depth