If you’ve been experiencing constipation, it’s possible that your vitamin supplements may be causing it. But there are things you can do to manage it.

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Constipation is when you have infrequent bowel movements or your stools are dry and hard to pass. Changes in your bowel habits can make you wonder what’s happening.

Constipation has many possible causes, including diet, health conditions, and medications. Sometimes, supplements can contribute to constipation.

Here’s what to know about the connection between vitamin and mineral supplements and constipation and what to do about it.

Just like medications, vitamin and mineral supplements may have side effects. Some supplements, such as iron and calcium, may cause constipation in some people.

But constipation has other causes too. If you’ve noticed more constipation lately, look at your supplements and consider other reasons you might be experiencing constipation.

Iron and calcium are two minerals associated with constipation. These minerals are often found in multivitamins, although the amounts vary. The higher the amount of iron or calcium, the more likely it is to cause constipation.

Many people find that supplements containing only iron or calcium are more likely to cause constipation. Those types of supplements usually have more iron or calcium than a multivitamin.

Iron and calcium can change the amount of fluid in your large intestine. Stool typically needs to hold on to moisture, which keeps it moving smoothly through your digestive tract. Iron and calcium can pull water out of your stool, making it dry. This slows the movement of your stool through your intestine.

If you think your supplement is causing constipation, there are things you can do about it. First, make sure you really need to take that supplement and that you need the dose you’re taking.

There are many reasons you might need to supplement iron, but not everyone needs to take a calcium supplement. There is debate about the role of calcium supplements in preventing fractures.

Ask your doctor or pharmacist whether there is a different formula that you might tolerate better. Lower doses may have fewer side effects. And some people find that taking a supplement every other day instead of every day reduces constipation.

If your calcium supplement has been causing constipation, consider using one with added magnesium. Magnesium is an essential nutrient for bone health. When combined with calcium, it may also reduce calcium’s constipating effects.

Here are some other strategies that can help you manage constipation:

  • Drink plenty of fluids.
  • Add more fiber to your diet with foods such as vegetables, fruits, whole grains, nuts, seeds, and beans.
  • Consider taking a fiber supplement such as Metamucil.
  • Ask a healthcare professional whether you could benefit from a probiotic supplement.
  • Get more physical activity if you can.

If you’re prone to constipation and you’re concerned that your supplement is making it worse, talk with a doctor. A different type or dose of the supplement may be less likely to cause constipation.

Also, do your best to drink lots of water and eat a high fiber diet. And if you need to take a supplement that is causing constipation, ask a doctor whether a laxative or stool softener might help manage it.

If you’re concerned about changes in your digestion due to taking supplements, discuss them with a doctor. If drinking more fluids and eating a high fiber diet is not helpful, ask a doctor whether there’s anything else you can do.

See a doctor if you have constipation and you:

  • are not seeing improvement with treatment
  • have bloating
  • have stomach pain
  • have blood in your stool
  • have a sudden change in your stool or frequency
  • experience unexpected weight loss
  • feel tired most of the time
  • are taking prescription medication such as opioids

Can vitamin D cause constipation?

It’s unlikely. A 2019 study suggests that low vitamin D levels may be associated with constipation. In those cases, supplementing vitamin D might help improve constipation.

But remember that everyone is different. If you suspect that vitamin D is causing constipation, consult a healthcare professional for advice.

What supplements can cause bowel problems?

Several supplements can affect bowel movements. Iron and calcium supplements are both associated with constipation.

Magnesium is a mineral that may cause diarrhea when taken at a high dose. It’s a good idea to stay below the upper limit of 350 milligrams of magnesium daily from supplements.

High doses of vitamin C may also cause diarrhea. To prevent it, consider staying below the daily upper limit of 2,000 milligrams of vitamin C.

Does too much B12 cause constipation?

Vitamin B12 is not typically associated with constipation. A 2021 study involving people who had undergone bariatric surgery found an association between constipation and high B12 levels. But the researchers believed that the constipation caused B12 levels to be high, not that the B12 caused the constipation.

Some supplements may increase your risk of constipation. This is especially true of calcium or iron supplements. Even a multivitamin and mineral supplement that contains calcium or iron may cause constipation in some people.

There are things you can do to prevent or manage constipation. Ask a doctor about other forms of calcium or iron that you might tolerate better. You can also do your best to stay active, drink lots of fluids, and eat a high fiber diet to help manage constipation.