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 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.

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.

Some products combine different types of laxatives, such as a stimulant and a stool softener. Combination products may not be any more effective than are single-ingredient products. But they may be more likely to cause side effects because of their multiple ingredients. Read labels carefully to see how many types of laxatives a product contains.

Interaction with medications
Your medical history and other medications you're taking may limit your laxative options. Laxatives can interact with blood thinners such as warfarin (Coumadin), antibiotics such as tetracycline, and certain heart and bone medications. Before using any laxative, read the label carefully. If you're not sure whether a particular laxative is right for you, ask your pharmacist or doctor. Don't exceed recommended dosages unless your doctor tells you otherwise.

Complicating conditions
Just because laxatives are available without a prescription doesn't mean that they're without risk. Laxative use can be dangerous if constipation is caused by a serious condition, such as appendicitis or a bowel obstruction. If you frequently use certain laxatives over a period of weeks or months, they can decrease your colon's natural ability to contract and actually worsen constipation.

Precautions for pregnant women and children
Don't give children under age 6 laxatives without a doctor's recommendation. If you're pregnant, get your doctor's advice before using laxatives. Bulk-forming laxatives and stool softeners are generally safe to use during pregnancy, but stronger laxatives can harm you or your baby. The stimulant laxative castor oil, for example, can cause uterine contractions. If you've recently given birth, consult your doctor before using laxatives. Although they're usually safe to use during breast-feeding, some ingredients may pass into breast milk and cause diarrhea in nursing infants.

Call your doctor immediately if you have bloody stools, severe cramps, pain, weakness, dizziness, unusual tiredness or rectal bleeding. You should also see a doctor if you have unexplained changes in bowel patterns or habits or if constipation lasts longer than seven days despite laxative use. If you're dependent on laxatives to have a bowel movement, ask your doctor for suggestions on how to gradually withdraw from them and restore your colon's natural ability to contract.

Apr. 23, 2011