Using Milk of Magnesia During Pregnancy

When it comes to pregnancy, there are many over-the-counter medications that are off-limits. But, the good news is that for most pregnant women, milk of magnesia is not one of them. Although you should always check with your doctor first before taking anything—even over-the-counter medications—most research indicates that short-term use of milk of magnesia is usually not harmful to you or your growing baby. The keywords, of course, are short-term use.

In fact, one study found that laxatives like milk of magnesia are poorly absorbed and their use has not been associated with adverse effects. However, researchers did indicate that expectant moms might experience bloating and flatulence when taking the medication. Additionally, they warn that prolonged use could lead to electrolyte imbalances.

Therefore, before you run out and purchase a bottle to treat your constipation, be sure to talk with your doctor first. Even though this over-the-counter medication is typically safe to use occasionally when you are pregnant, you may have special circumstances in which it is not recommended for you. In the meantime though, here is an overview of everything you need to know about milk of magnesia.

What Is Milk of Magnesia?

Milk of magnesia, or magnesium hydroxide, is a saline laxative that is typically used to treat constipation. This type of laxative is also known as a "salt" and is meant to be fast-acting. Typically, you can expect to have a bowel movement within 30 minutes to six hours of taking the medication.

Milk of magnesia works by drawing water to the bowel from nearby tissues. In turn, this water then softens and moistens your stool and helps get things moving in your bowels.

Is Milk of Magnesia Pregnancy-Safe?

In general, milk of magnesia is safe to use during pregnancy. But, keep in mind that just like any other drug, there are still some risks. For instance, it's possible for this laxative to interact with some of your other medications and supplements. Milk of magnesia also is known to cause issues for people on low magnesium diets or for those with kidney disease.

What's more, if you have recurring bouts of constipation, you need to talk with your doctor. Milk of magnesia is not recommended for long-term treatment for constipation prevention in pregnant women.

Treating Your Constipation

If you are struggling with constipation, you are not alone. Constipation is common in pregnant women. In fact, as many as 38% of pregnant women will experience difficulty having bowel movements.

Much of this phenomenon can be attributed to changing progesterone levels and the increased water absorption of the intestines that causes your stools to dry out. Add to this the fact that pregnant women are taking higher levels of vitamins and often do not move around as much, and you can understand why pregnant women are prone to constipation.

But, you do not have to suffer in silence. After getting your doctor's approval, use milk of magnesia exactly as directed. Keep in mind that if you use too much, it can cause abdominal pain, vomiting, and diarrhea. Also, be sure to drink plenty of water while taking the medication and talk to your doctor about the risk of electrolyte imbalances. Your doctor may recommend that you drink Pedialyte or something similar while taking the medication.

You also should try more natural methods for dealing with your constipation like changing up your diet and moving around more. Here are a few additional tips:

  • Increase your fiber intake. Add roughage to your diet like whole grains, fruits, vegetables, and legumes. These foods help keep things moving through your system.
  • Drink more water. Increasing the amount of water you drink will help move food through your digestive tract and soften your stools. A good goal is 10, 8-ounce glasses of water a day.
  • Move around more. Water aerobics, walking regimens, and yoga will increase the muscle activity in your intestines helping you move waste through your system more quickly.

Also keep in mind that taking a laxative like milk of magnesia too often can make any foods that you eat go through the body faster than usual, which may reduce the amount of nutrients absorbed into the body.

This, in turn, can lead to nutritional problems for you and your baby if milk of magnesia is overused. Likewise, using more than the recommended amount can lower the levels of needed salts in the blood. So, be sure to limit your use of milk of magnesia.

When to Call Your Doctor

Most doctors generally believe milk of magnesia is safe to use during pregnancy, even though there is limited evidence on whether or not the laxative can harm your developing baby. Just make sure you get the green light from your doctor before taking it. You also should adhere to your doctor's instructions regarding dosing and the length of time you can use the drug. Overdoing it can create a number of issues for you and your baby.

If, after taking the medication, you experience loose, watery stools that won't go away or if you have blood in your stools, be sure to contact your doctor right away. You also should call your doctor immediately if you still cannot have a bowel movement and it has been six hours or more since you took milk of magnesia. You may have an underlying medical condition that needs treatment. So, don't delay in reaching out for help.

A Word From Verywell

Remember, when you're pregnant, there is no such thing as being too careful. So, call your doctor before taking any over-the-counter medications, including milk of magnesia. And, if after taking the medication, something still just doesn't seem right, don't hesitate to contact your doctor. You want to make every effort to stay safe and healthy during your pregnancy. No question or concern is off-limits.

1 Source
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Trottier M, Erebara A, Bozzo P. Treating constipation during pregnancyCan Fam Physician. 2012;58(8):836–838.

By Sherri Gordon
Sherri Gordon, CLC is a published author, certified professional life coach, and bullying prevention expert.