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 experienced the discomfort of constipation, you may have tried over-the-counter laxatives. A number of factors — including a poor diet, physical inactivity, pregnancy, illness, travel and some medications — can disrupt normal bowel function and cause constipation. However, laxatives may not be the solution.

How often you have a bowel movement varies, but people normally have as many as three bowel movements a day to as few as three a week. You may be constipated if you have fewer bowel movements than are normal for you. In addition, constipation may involve stools that are difficult to pass because they're hard, dry or small.

However, before turning to laxatives, try these lifestyle changes to help with constipation:

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

Lifestyle 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, also referred to as fiber supplements, are the gentlest on your body and safest to use long term. Metamucil and Citrucel fall into this category.

Stimulant laxatives, such as Dulcolax and Senokot, are the harshest and should be used only occasionally.

Here are some examples of types of laxatives. 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 work Side effects
Oral osmotics (Milk of Magnesia, Miralax) Draw water into the colon from surrounding body tissues to allow easier passage of stool Bloating, cramping, diarrhea, nausea, gas, increased thirst
Oral bulk formers (Benefiber, Citrucel, FiberCon, Metamucil) Absorb water to form soft, bulky stool, prompting normal contraction of intestinal muscles Bloating, gas, cramping or increased constipation if not taken with enough water
Oral stool softeners (Colace, Surfak) Add moisture to stool to allow strain-free bowel movements Electrolyte imbalance with prolonged use
Oral stimulants (Dulcolax, 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 nutrients. Some laxatives can lead to an electrolyte imbalance, especially after prolonged use. Electrolytes — which include calcium, chloride, potassium, magnesium and sodium — regulate a number of 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 more effective than single-ingredient products are but may be more likely to cause side effects. Read labels to make sure you know what you're taking, and use with caution.

Interaction with medications

Your medical history and medications you're taking may limit your laxative options. Laxatives can interact with blood thinners such as warfarin (Coumadin), some antibiotics, and certain heart and bone medications. Read labels carefully. If you're not sure whether to try a particular laxative, ask your pharmacist or doctor. Don't exceed recommended dosages unless your doctor tells you otherwise.

Complicating conditions

Laxative use can be dangerous if constipation is caused by a serious condition, such as appendicitis or a bowel obstruction. If you frequently use laxatives for weeks or months, they can decrease your colon's 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, ask your doctor before using laxatives. Bulk-forming laxatives and stool softeners are generally safe to use during pregnancy, but stimulant laxatives may be harmful.

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 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.

Jun. 06, 2014