When you've gotta "go" and your body just can't seem to make it happen, laxatives can be a helpful way to find relief. Laxatives are a type of medicine or substance that can trigger a bowel movement, per the Mayo Clinic. They can be prescribed or purchased over-the-counter to relieve the effects of constipation.
Laxatives should become an option only if lifestyle and diet changes aren't doing the trick, according to Jacqueline Wolf, MD, a Boston-based gastroenterologist. And how quickly they work will depend on the person and how your body responds.
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Here, Dr. Wolf explains how laxatives should be used, the potential side effects, natural laxative alternatives and when to see a doctor about constipation.
How Laxatives Work
There are several types of laxatives, but the common first choice is a bulk-forming laxative (e.g. fiber supplements). Bulk-forming laxatives work by drawing water into the stool, adding bulk and moisture, which allows a bowel movement to pass easier, according to Harvard Health Publishing.
These can be purchased over-the-counter and are generally the gentlest and safest long-term laxative option, per the Mayo Clinic. Examples of bulk-forming laxatives include Metamucil ($29.48, Amazon) and Citrucel ($19.79, CVS).
Other categories of laxatives include stool softeners and stimulants. Stool softeners (also known as saline laxatives) draw fluids into your colon from nearby body tissues, which then helps soften stool, per the Mayo Clinic. Examples of saline laxatives include milk of magnesia ($5.98, Walmart) and polyethylene glycol or Miralax ($12.49, CVS).
Stimulant laxatives induce a bowel movement by causing the colon to contract and push stool out of your body. A popular brand of stimulant laxative is Dulcolax ($5.99, Amazon).
The timeframe in which a laxative works its magic depends on the person, but you'll rarely have instant relief. "One dose may or may not work, and there will likely be a delay, maybe even for a few days," Dr. Wolf says.
When Is the Best Time to Take a Laxative?
When to take a laxative depends on the form of laxative you choose.
- Bulk-forming laxatives (oral laxatives): These should be taken after meals with a full glass of cold water or juice, according to the Mayo Clinic. Hydration is an important part of the process for the laxative to work. "You have to drink a lot of water," Dr. Wolf says. "Oral laxatives draw water into the bowel, so it might not work if you don't have a lot of fluid."
- Stimulant laxatives: If you're taking a stimulant laxative like Dulcolax, having an empty stomach can speed up its effect. Taking a stimulant laxative after eating may slow down results, per the Mayo Clinic. These types of laxatives should be taken at least one to two hours after a meal, once the food has been digested.
- Stool softeners (saline laxatives): If you take a saline option, like milk of magnesia or Miralax, it's best taken at the end of day, around bedtime, per the National Institutes of Health (NIH).
If you're still not sure on timing, check the medication's label for instructions on how to take it, or talk to your doctor or a pharmacist about how to take a laxative for best results.
Should You Take a Laxative After Eating Too Much?
Laxatives are meant to treat constipation, not overeating, Dr. Wolf says. If you've eaten too much, you should not turn to a laxative to relieve yourself. This could actually be considered laxative abuse, according to the National Eating Disorders Association (NEDA).
Laxative abuse is when someone misuses laxatives to get rid of unwanted calories or lose weight, per NEDA. Laxatives do not work by rushing out food or calories after consuming them, and misusing them can have serious health consequences.
If you suspect you're abusing laxatives or struggling with an eating disorder, the NEDA Helpline can be reached online or via phone at (800) 931-2237.
Side Effects of Laxatives to Know
There are possible side effects from taking laxatives, including gas, bloating, cramping, nausea, vomiting and diarrhea, per the U.K.'s National Health Service (NHS).
"There could also be more trouble controlling bowel movements if it's loose diarrhea, and it's possible to have electrolyte depletion." Dr. Wolf says.
And as far as milk of magnesia goes, Dr. Wolf warns that this supplement is not for everyone.
"It should not be taken by people with kidney problems, because you may get an increased amount of magnesium," she says. "It draws a lot of fluid into the bowel, which can cause dehydration and decrease kidney function."
You should stop taking laxatives and seek immediate medical attention if you experience bleeding from your rectum or if you are still constipated after using a laxative, according to Cornell Health. Dr. Wolf also advises that you should not take laxatives if you have gastrointestinal issues.
Alternatives to Laxatives
Laxatives should only be used for short-term relief of constipation when other lifestyle and diet changes aren't helping. If you are experiencing frequent constipation, diet changes may help relieve your discomfort, Dr. Wolf explains.
"One of the first things to do before taking laxatives is to make sure that you're eating enough fiber and drinking enough water," she says.
The recommended amount for daily fiber intake is about 28 grams per day, according to the United States Department of Agriculture (USDA). You can add more fiber to your diet by eating foods like whole grains, fruits and vegetables.
Dr. Wolf suggests trying these foods with high fiber content:
In addition, make sure you're drinking plenty of fluids. An easy way to calculate how many ounces of water you should drink per day is to divide your body weight (in pounds) by two. For example, if you weigh 180 pounds, you should aim to drink about 90 ounces of water, or about 11 cups.
Getting regular exercise is another important lifestyle factor that can help prevent constipation. (When you move, your gut moves, too.) The Physical Activity Guidelines for Americans recommend adults get at least 150 minutes of moderate-intensity cardio (like walking) or 75 minutes of vigorous-intensity exercise (like running) every week.
When to See a Doctor About Constipation
If you're still dealing with constipation after taking laxatives, it could be time to see a doctor. Symptoms like severe abdominal pain, fatigue and sudden weight loss should be taken seriously and could be a sign of a serious health condition.
Another red flag is if there is blood in the stool, Dr. Wolf says. You should also take note of whether your appetite has changed or if your regular day-to-day routine has to be altered because of constipation.
- National Health Service: "Laxatives"
- Harvard Health Publishing: "Don't Bomb the Bowel with Laxatives"
- Cornell Health: "Laxative Use: What to Know"
- United States Department of Agriculture: "How Much (Dietary) Fiber Should I Eat?"
- Mayo Clinic: "Laxative"
- NIH: "Milk of Magnesia"
- National Eating Disorders Association: "Laxative Abuse"
- Office of Disease Prevention and Health Promotion: "Physical Activity Guidelines for Americans, 2nd Edition"
Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.