What you should know about laxatives for regularity

If you’re piling on the beans, whole grains, fruit, and veggies and you still aren’t regular, it may be time to consider an over-the-counter laxative.

(Looking for info about psyllium fiber supplements or wheat bran? Click here.)

Laxatives come in two main varieties:

Osmotic. “Osmotic laxatives draw water into the colon, which softens the stool and makes them easier to pass,” explains Jacqueline Wolf, a gastroenterologist and associate professor of medicine at Beth Israel Deaconess Medical Center in Boston. “Those are the most gentle of the laxatives.”

Polyethylene glycol—the active ingredient in MiraLAX—is the most widely studied laxative.

In the two main studies that compared MiraLAX to a placebo in roughly 440 adults with chronic constipation, those randomly assigned to take the laxative every day for two weeks to six months had two to three more bowel movements per week and reported less straining. (Both studies were funded by MiraLAX’s manufacturer.)

“It’s both safe and effective, so it’s worth a try,” says Lucinda Harris, a gastroenterologist and associate professor of medicine at the Mayo Clinic in Scottsdale, Arizona.

Stimulant. Stimulant laxatives move the stool along by helping the colon contract. They include senna (the active ingredient in Ex-Lax) and bisacodyl (in Dulcolax Overnight Relief).

No good trials have tested senna in people with chronic constipation.

In one study funded by the maker of Dulcolax, researchers randomly assigned 356 British adults with chronic constipation to take a placebo or up to 10 milligrams of Dulcolax a day. Over the next four weeks, the Dulcolax takers had roughly five bowel movements per week (and reported less straining) compared with just two per week for the placebo takers.

The downside? Those taking Dulcolax had far more bouts of diarrhea and abdominal pain.

Are laxatives dangerous?

“They’re usually safe if you use them at the dose on the label,” says Harris. “But if you overuse laxatives, you can get chronic diarrhea and can disturb the body’s balance of electrolytes like potassium and magnesium.” That can lead to dehydration and, in extreme cases, heart or kidney failure.

“If you’re taking laxatives daily, consult your doctor,” suggests Wolf. Something else may be going on that a doctor can help you address. Or your doctor may recommend a prescription medication.

“A pill is not necessarily going to make you all better, but it may be helpful along with other lifestyle changes.”

Photo: Goffkein/stock.adobe.com.

Nutrition Action doesn’t accept any paid advertising or corporate or government donations. Any products recommended by Nutrition Action have been vetted by our staff and are not advertisements by the manufacturers. The information in this post first appeared in the June 2020 issue of Nutrition Action Healthletter.


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