Is milk of magnesia safe during pregnancy?

What does the evidence say about milk of magnesia during pregnancy?

1. Osmotic laxatives including magnesium hydroxide are among the over-the-counter categories reviewed, and at recommended doses these products are not expected to raise the chance of birth defects. 1
2. One tablespoon of Phillips' Milk of Magnesia delivers 500 mg of elemental magnesium, well above the daily upper limit that applies to supplements and medications. 2
3. High magnesium doses from supplements or medications commonly bring on diarrhea alongside nausea and abdominal cramping, and the risk of magnesium building up rises when kidney function is reduced. 2
4. Constipation affects roughly 35% of women in the first trimester and 39% in the second before easing to about 20% in the third, and iron intake can make it worse. 3
5. The pooled pregnancy evidence on laxatives remains thin, drawing on only 180 women across two studies, with fiber raising stool frequency by about 2.24 times per week. 4

Is milk of magnesia safe in each trimester?

• First trimester. Constipation frequently begins in the first trimester, and prenatal iron often sharpens it. Fiber, fluid, and movement come first, with an occasional osmotic dose as a next step your provider can weigh in on.
• Second trimester. Constipation is most common through the middle of pregnancy. If you are reaching for milk of magnesia more than occasionally, that is worth a conversation rather than a bigger dose.
• Third trimester. Repeated dosing late in pregnancy raises the practical concern of fluid and electrolyte loss at a point when your fluid needs are already high. Ask your provider which option fits your situation.