Bottle of multi-colored multivitamins against a yellow background

Can multivitamins cause constipation? Here's what to know

Medically reviewed on August 1, 2022 by Karen Janson, M.D. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Table of contents

For weeks, you’ve put your physical and mental health first, taking a multivitamin recommended by your healthcare provider. However, you may have discovered that one bodily function has been anything but regular: your bowel movements. After running through a list of possible causes for your constipation and bloating, you settle on a likely offender: your new multivitamin. But can multivitamins cause constipation?

The answer is yes and no. While multivitamins as a whole don’t cause constipation, some vitamins and minerals present in them may contribute to irregularity.

Fortunately, we’re here to fill you in on these stool-stopping dietary supplements so you can keep receiving the benefits of multivitamins without the pain of blocked bowels.

Which vitamins and minerals cause constipation?

Like a well-oiled car, a multivitamin is a supplement composed of many “parts” that work together to get you where you need to go. In supplement-speak, these parts are the individual vitamins and minerals.

However, experts have linked some vitamins and minerals to increased constipation. The most commonly-cited culprits include:

  • Iron [1]
  • Calcium [2]
  • Folic acid [3]
  • Vitamin D [4]

Let’s break down each of these culprits in more depth.


When it comes to keeping your bloodstream in tip-top shape, few minerals are more essential than iron.

In short, taking an iron supplement helps the body produce enough red blood cells to: [1]

  • Carry oxygen throughout the bloodstream
  • Remove carbon dioxide from the bloodstream
  • Produce a vital protein called hemoglobin

Without sufficient iron, you’re at a greater risk of iron deficiency anemia. However, experts have also linked increased iron to the following intestinal issues: [5]

  • Abdominal pain
  • Bloating
  • Diarrhea
  • Constipation

To help prevent these negative intestinal issues, healthcare providers recommend taking only your prescribed iron dosage and avoiding large doses after six months of continual supplementation.


If your parents ever told you to drink a glass of milk for strong bones, you’ve really been told to increase your calcium intake. That’s because calcium is one of the top minerals in dairy products, supporting the following: [2]

  • Skeletal and bone health
  • Heart health
  • Blood circulation
  • Hormone regulation

Most people receive enough calcium through their diet. However, if you can’t meet the recommended daily amount of 1,000-1,200 mg for people aged 19-71, you may have to add a calcium supplement to your diet. [6]

That said, it’s best to take only your prescribed calcium dosage. Excess calcium can lead to constipation. [7]

Folic acid

Also known as vitamin B9, folic acid helps create red blood cells. Additionally, taking the folic acid vitamin supplement may help: [8]

  • Reduce birth defects (especially neural defects)
  • Decrease the risk of heart disease and stroke
  • Reduce the risk of some cancers
  • Treat some forms of depression

Just as many people meet their daily calcium requirement from their diet, so too do they meet their daily folic acid requirement—especially by consuming dark leafy greens and beans.

However, if you can’t meet your daily folic acid through diet alone, you may need to take a vitamin B9 dietary supplement. This is especially true if you’re pregnant or may become pregnant.

That said, like calcium, too much folic acid can lead to constipation and bloating. [3] As a result, healthcare providers recommend limiting your folic acid intake to your prescribed dose.

Vitamin D

Calcium’s bone-supporting sidekick, vitamin D is crucial for bone health. Without vitamin D, your body can’t absorb calcium—no matter how many calcium supplements you take.

Additionally, taking vitamin D supplement helps support:

  • Brain function
  • Muscle health
  • Immune health

The good news is that your body produces vitamin D through sunlight, and some foods contain vitamin D.

However, if you’re not receiving adequate amounts of vitamin D through diet and sunlight, you may have to take a supplement. Dietitians recommend 600 international units (IU) daily of vitamin D for people aged 1-70. [9]

On the flip side, too much vitamin D (more than 4,000 IU per day) can lead to constipation and bloating—especially in children, pregnant women, or breastfeeding women.

How to best prevent constipation caused by multivitamins

The easiest way to prevent constipation caused by multivitamins is to limit consumption of constipation-causing vitamins and minerals.

For instance, if you’re choosing between two multivitamins with different iron levels, it may be best to go with the supplement that contains the least amount of iron—especially if you can make up the difference through your diet.

Taking individual vitamins and minerals is another way to limit constipation.

For example, if you only need to take a vitamin D3 supplement, why throw in a bounty of bowel-breaking vitamins and minerals? Only take the vitamins and minerals you need to keep you happy and healthy.

Vitamin health with Everlywell

A leader in digital healthcare, we have the tools you need to determine whether you’re lacking in essential vitamins like vitamin D as well as a suite of vitamins and supplements. Whether you need a Vitamin D Test or a daily multivitamin, we have your health covered.

Vitamins and Supplements 101: An expert breaks down the vitamins you actually need — and how to make them most effective

Multivitamin benefits: key points to know

What to look for in a multivitamin


  1. Iron. National Institute of Health. URL. Accessed August 1, 2022.
  2. Calcium. National Institute of Health. URL. Accessed August 1, 2022.
  3. Side effects of folic acid. National Health Service. URL. Accessed August 1, 2022.
  4. Chronic functional constipation is strongly linked to vitamin D deficiency. National Library of Medicine. URL. Accessed August 1, 2022.
  5. Iron Supplement (Oral Route, Parenteral Route). Mayo Clinic. URL. Accessed August 1, 2022.
  6. Calcium and calcium supplements: Achieving the right balance. Mayo Clinic. URL. Accessed August 1, 2022.
  7. Are You Taking Too Many Calcium Supplements? Cleveland Clinic. URL. Accessed August 1, 2022.
  8. Folate (folic acid). Mayo Clinic. URL. Accessed August 1, 2022.
  9. Vitamin D. Mayo Clinic. URL. Accessed August 1, 2022.
Everlywell makes lab testing easy and convenient with at-home collection and digital results in days. Learn More