Can you take milk of magnesia while pregnant?

Can you take milk of magnesia while pregnant?

Milk of magnesia (magnesium hydroxide) is classified as an osmotic laxative and is generally considered safe in pregnancy when taking the recommended dosage and only for occasional use. It works by drawing water into the intestines to soften stool and stimulate bowel movements. Most healthcare providers consider it an acceptable short-term option for pregnancy constipation.

That said, there are some important distinctions between using milk of magnesia as an occasional remedy versus relying on it regularly.

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Why constipation is so common during pregnancy

Pregnancy hormones, particularly progesterone, slow down the movement of food through the digestive tract. This gives your body more time to absorb nutrients (which is helpful), but it also means stool sits in the colon longer, losing water and becoming harder to pass.

Iron supplementation compounds the issue. Most prenatal vitamins contain iron, and iron is a well-known contributor to constipation. The combination of hormonal changes and supplemental iron means constipation affects an estimated 40% of pregnant women.

Safety considerations

Milk of magnesia is a Category A or B medication in pregnancy (depending on the classification system) and is on many providers' "safe to use" lists. The main risks with repeated or excessive use include dehydration and electrolyte imbalances, both of which are more concerning during pregnancy because your body's fluid needs are already elevated.

Please speak with your medical team before taking milk of magnesia. If you're using milk of magnesia more than occasionally, it's worth talking to your provider about underlying causes and longer-term solutions.

Better long-term strategies for pregnancy constipation

Dietary fiber. Gradually increasing fiber through fruits, vegetables, legumes, and whole grains is the most sustainable approach. Aim for 25-30 grams per day.

Hydration. Drink at least 8-12 cups of water daily. Dehydration makes constipation worse.

Movement. Regular light exercise, even walking, can help stimulate bowel motility.

Magnesium supplementation. A daily magnesium supplement in a gentler form (like magnesium glycinate or citrate) can support regularity without the intensity of a laxative dose. This approach addresses the underlying mineral need while providing a milder, more consistent effect.

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A note from WeNatal on digestive comfort during pregnancy

WeNatal Rest + Digest Magnesium was designed with pregnancy constipation in mind. The blend includes magnesium citrate to support regular bowel movements alongside magnesium glycinate, malate, and gluconate for relaxation, sleep, and nervous system support. It pairs naturally with WeNatal for Her, which uses Ferrochel® iron bisglycinate, a form specifically chosen because it's gentler on the digestive system than standard iron forms.

RELATED: Magnesium for better sleep and digestion: Benefits, best types, and Oura ring insights

References

Salari N, Mohamadi S, Hemmati M, et al. Global prevalence of constipation during pregnancy: a systematic review and meta-analysis. BMC Pregnancy Childbirth. 2024;24(1):836. Published 2024 Dec 20. doi:10.1186/s12884-024-07057-y