13 Surprising Causes of Constipation

13 Surprising Causes of Constipation

You may already know that a lack of dietary fiber can cause constipation. But there are many less-obvious factors that threaten regularity. Do any of these sneaky constipation causes apply to you?

By Madeline Vann, MPH

Medically reviewed by Lindsey Marcellin, MD, MPH

Everyone is affected by constipation now and then — your diet, travel, and a lack of activity can all trigger a brief bout. But you might be surprised by the conditions and other factors that can be responsible for longer term or chronic constipation. The list is wide-ranging, from pregnancy constipation to a side effect of antidepressants.

Some of these causes of constipation can be handled at home with an over-the-counter product or changes in your medicine cabinet, but serious constipation warrants a prompt doctor's visit.

"Constipation that's new, different, associated with bleeding or weight loss, and lasts a couple of days may be a sign of colon cancer," says gastroenterologist Benjamin Krevsky, MD, associate chief of the section of gastroenterology at Temple University in Philadelphia, Pa. But since there are several more common causes of constipation that aren't as serious, don't worry too much. Your doctor can help you determine what's really behind your constipation.

Sneaky Causes of Constipation

Here's an overview of some of the conditions that may be to blame for your discomfort:

·         Hypothyroidism. "The thyroid is a general regulator and affects organs all over the body," explains Dr. Krevsky. This includes the bowel. Your family doctor might miss this, but a gastroenterologist who sees this effect several times a year will probably test you for hyperthyroidism and can treat it to relieve your chronic constipation.

·         Hyperparathyroidism. Less common than hypothyroidism, an overactive parathyroid — a gland close to the thyroid — can also be a cause of constipation. Simple testing and treatment will also bring relief.

·         Prescription painkillers. Opioids — not over-the-counter pain relievers — can cause constipation. For people recovering from surgery or managing chronic pain, this side effect can be an obstacle to quality of life (or possibly, hospital discharge). Solutions include taking different pain medications or adding a laxative. Krevsky explains that research in this area is progressing and within the next several years doctors might have new medications to treat pain without causing constipation.

·         Laxatives. Ironically, the laxative you are taking could ultimately lead to chronic constipation. Your body builds up a tolerance to medications that act as stimulant laxatives, such as castor oil. Technically, says Krevsky, they aren't causing constipation so much as failing to ease it. A better bet for laxatives that won't lead to tolerance is milk of magnesia or polyethylene glycol (Miralax).

·         Antidepressants. Constipation was one of the unpleasant side effects of an older class of antidepressants called tricyclics. "That's because they interfere with the transmission of nerves that stimulate the bowel to move," says Krevsky. Constipation is a much less common but still possible side effect of the more modern SSRI antidepressants. Talk to your doctor about whether you should take a different antidepressant or add a laxative.

·         Antacids. So you have heartburn and now, to add to your misery, constipation sets in. Antacids that contain aluminum are the likely culprit, says Krevsky. Read the ingredient list and make a switch if necessary. Try an over-the-counter acid controller medication, or better yet, talk to your doctor. If you take antacids often enough to get chronic constipation, you should probably be tested for gastroesophageal reflux disease (GERD).

·         High blood pressure medications. Chronic constipation is a side effect of an older class of high blood pressure medications called diuretics, which act on the salt in your body to control fluid levels. "You get dehydrated and your body steals moisture from the stool," says Krevsky. You cannot compensate by drinking more water than you need — you'll just lose it through urination. The solution is to talk to your doctor about a switch in blood pressure medication or adding a laxative.

·         Irritable bowel disease (IBD). Though diarrhea is more associated with IBD, some people with Crohn's disease that affects the small bowel will get chronic constipation. In this case, you need more aggressive therapy for the IBD or surgery, says Krevsky.

·         Pregnancy. Pregnancy constipation is a common problem. Early in pregnancy, constipation may be caused by changing hormones or your diet; in later months, the pressure that the baby is putting on your organs becomes the culprit. Don't strain, warns Krevsky, because this can cause hemorrhoids, which will just make you more uncomfortable. And don't take a laxative without talking to your ob-gyn first.

·         Diabetes. People who have diabetes face a number of potential health problems, including chronic constipation. "This is in large part due to the nerve inflammation that goes along with being a diabetic," Krevsky says. Solutions include getting better control of diabetes to prevent more damage and talking to your doctor about medication to fight constipation.

·         Heavy metal poisoning. Many family doctors don't think about lead poisoning as a cause of constipation, but a work-up occasionally reveals significant exposure to lead, which can come from chipping old paint and other sources of exposure at home. Nerve damage is one of the outcomes of heavy metal poisoning, and this can affect the normal function of the bowels.

·         Supplements. Calcium supplements and iron supplements both can cause constipation. If you suspect either one, get a recommendation from your doctor for a better way to supplement if you are truly deficient.

·         Diseases of the colon. Any painful colon problem, such as an anal fissure or hemorrhoids, can cause chronic constipation because people avoid bowel movements and "detrain their bowel to work properly," Krevsky explains. Treating the underlying cause can end this type of constipation.

Finally, Krevsky suggests, it's possible that you don't actually have constipation at all. He explains that while many people have a bowel movement regularly, such as once or twice a day, there are others who only do so two or three times a week — and they are just fine. Call this a hazard of pharmaceutical and food product advertising, but Krevsky says he occasionally has patients who are convinced they are constipated because they have seen ads promoting daily regularity. But as long as you're being regular, you're probably fine, as long as this doesn't change and you don't feel any discomfort.

If you are constipated and worried about the cause, check in with your doctor. Ending your chronic constipation could be as simple as choosing a better over-the-counter laxative or getting better control over a chronic health problem.