Milk Of Magnesia During Pregnancy: Safety, Benefits And Side Effects

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Milk of magnesia or magnesium hydroxide is a laxative that helps prevent constipation, indigestion, and an upset stomach. It is safe to consume milk of magnesia during pregnancy if prescribed by your doctor (1).

It is an osmotic laxative, i.e., it softens the stool by drawing water into the intestines (2).  Some expecting mothers may experience pain and discomfort due to gastric disturbances when consuming these laxatives. Hence, inform your doctor if you experience any unusual symptoms after consuming milk of magnesia.

Read on to learn about the types, dosage, benefits, safety, side effects, and efficacy of milk of magnesia during pregnancy.

In This Article

Safety Of Milk Of Magnesia During Pregnancy

The over-the-counter medications are safe for short-term use during pregnancy. However, prolonged use of milk of magnesia during pregnancy may have some side effects.

Seek a doctor’s advice before taking it, and if the constipation symptoms do not improve for three consecutive days of consuming it ((1).

It is advisable not to take milk of magnesia if you have any of the following health issues (1).

Milk of magnesia during pregnancy is not advisable

Image: IStock

  • Nausea
  • Vomiting
  • Kidney disease
  • On a low-magnesium diet
  • Allergic to magnesium or other constituents of the laxative
  • Blockage in the gastrointestinal tractiXA set of organs responsible for ingestion, digestion, and absorption of food and excretion of the waste
  • Fecal impactioniXDifficulty passing the hardened stool through the colon or rectum, often caused by chronic constipation

Types And Dosage Of Milk Of Magnesia During Pregnancy

Milk of magnesia is also available in a chewable tablet form

Image: Shutterstock

According to the Health Products Regulatory Authority (HPRA), you can orally consume the milk of magnesia for constipation,upset stomach,or dyspepsia (1). The dosage is different in each case, and you should adhere to the dosage as prescribed by the doctor. IOverdosage is not advisable.

The laxative is available in chewable tablets and concentrated liquid forms. The chewable tablet requires chewing before swallowing, and you can take the concentrated form along with milk or water.

There are limited studies on the dosage regime of milk of magnesia consumption during pregnancy. The doctor will suggest the dosage as per your requirement. The general dosage recommendations include.

  • For constipation: An adult can take 30-45ml (6-8 times in a dosing cup) as a single dose at bedtime.
  • For other digestive issues: An adult can take 5-10ml (1-2 times in a dosing cup) as a single dose. In a day, a maximum of 60ml is suggested.

Benefits Of Taking Milk Of Magnesia During Pregnancy

Milk of magnesia has several health benefits. During pregnancy, it is normal to get magnesium deficiency.

You may take it in case of the following conditions upon doctor’s consultation (2):

  • Heartburn and acid reflux
Milk of magnesia during pregnancy can help fight heartburn

Image: IStock

  • Chronic constipation
  • Magnesium deficiency
  • Stomach upset
  • Gastroesophageal reflux

Side Effects Of Milk Of Magnesia During Pregnancy

Milk of magnesia may cause the following side effects (1) (3):

  • Bloating
  • Flatulence
  • Electrolyte imbalance
  • Abdominal pain
protip_icon Be watchful
Some laxatives may cause abdominal cramping, and it may be difficult to distinguish between cramping and uterine contractionsiXPeriodic tightening of the uterine muscles during pregnancy or childbirth or preterm laboriXEarly signs of labor, typically happening before the completion of 37 weeks of pregnancy pain (12).

Complications Of Milk Of Magnesia Consumption During Pregnancy

The milk of magnesia should not be consumed exceeding its dosage regime during pregnancy. An overdose may increase the risks of side effects and associated complications. The following are the complications associated with the regular use of milk of magnesia during pregnancy (3) (4) (5).

  • Magnesium poisoning or hypermagnesemia
  • Those having kidney disease or diabetes may be prone to electrolyte imbalance

Remedies For Constipation During Pregnancy

Constipation can occur during pregnancy in response to hormonal changes. Some  measures that help ease constipation during pregnancy are (6) (7) (8) (9) (10):

  • Diet: Increase fiber intake in your diet by including more vegetables and fruits such as apples, lentils, and bananas.
Probiotics can help combat constipation during pregnancy

Image: Shutterstock

  • Fluid intake: Consume lots of water, fruit juice, and rehydration supplements.
  • Laxatives: Soluble fiber (psylliumiXA high fiber derivative of the seeds from the Plantago ovata plant, also used to treat constipation ) or osmotic agents (milk of magnesia, polyethylene Glycol (PEG), and lactulose) help treat constipation.
  • Medications: The doctor may prescribe medication in case of severe constipation if the benefits outweigh the risks. Tegaserod is an FDA-approved medication in category B type. There are no human trials on the adverse effects of the drug. However, animal trials suggest it might harm the fetus.
  • Biofeedback therapy: NeuromusculariXConditions or phenomenon concerning the structure and function of nerves and muscles in the body stimulation can help improve bowel movement Training with visual and auditory signals can treat pelvic floor muscle weakness and bowel movements.
  • Enema: Rectal enemaiXA technique where a fluid is injected into the rectum to expel the stool might help relieve constipation during pregnancy and childbirth.
  • Don’t forget to stay active. Along with boosting mood, regular physical activity can reduce constipation.
protip_icon Quick tip
You can check with your doctor if they can change your prenatal vitamin. Some prenatal vitamins may cause constipation (13).

Seeking Doctor’s Advice

Certain symptoms warrant medical checkup

Image: IStock

After consuming the milk of magnesia, pregnant women may note the following signs of discomfort and seek medical attention.

  • Prolonged loose and watery stool
  • Unable to pass a stool after six to twelve hours of consumption
  • Unable to get relief after consuming the laxative for three consecutive days

Can Milk Of Magnesia Cause Congenital Disabilities?

The FDA does not approve milk of magnesia for consumption during pregnancy. You can only take it under doctor’s advice. It is not known to cause any congenital disability or other risks to the fetus (11).

Frequently Asked Questions

1. How quickly does milk of magnesia work?

You can expect a bowel movement within half an hour to six hours of taking milk of magnesia (12).

2. Why should I take milk of magnesia at bedtime?

Taking milk of magnesia before bedtime is more effective since it can draw the maximum possible water into your intestines and help you have a smooth bowel movement the next morning.

3. Does milk of magnesia cross the placenta?

Magnesium is reported to cross the placenta; therefore, it is advised not to take milk of magnesia toward the end of pregnancy when you are nearing delivery (14).

4. How much water should I drink with milk of magnesia?

During the consumption of milk of magnesia, doctors recommend drinking at least eight ounces of water (15).

Using milk of magnesia during pregnancy is usually safe to treat constipation. It is available over the counter, but one needs to seek the doctor’s clearance before using it during pregnancy. Prolonged use of milk of magnesia in pregnancy may lead to some complications. Eating a healthy, fiber-rich diet and taking ample fluids can help achieve a healthy gut and prevent constipation. Your doctor will prescribe the necessary amount of milk of magnesia for you after a thorough evaluation.

Infographic: Can Other Drugs Interact With Milk Of Magnesia?

Pregnant women may take milk of magnesia to ease constipation. Usually, certain dietary supplements and other medications may be prescribed during pregnancy, and they may interact with this laxative. So it’s crucial to discuss this with your healthcare provider. The infographic below provides a list of medicines that may interact with milk of magnesia.

drug interactions of milk of magnesia (MoM)(infographic)

Illustration: Momjunction Design Team

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Download Infographic in PDF version

Key Pointers

  • Milk of magnesia can act as a laxative and is prescribed to relieve problems such as indigestion and stomach upset during pregnancy.
  • Consuming milk of magnesia while pregnant could pose some side effects, such as diarrhea and bloating, and it may not be recommended for women with certain conditions.
  • Seek medical advice and be well-aware of the possible risks of taking milk of magnesia during pregnancy.


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
  1. Milk of Magnesia.
  2. Treatment of Constipation in Older Adults.
  3. Laxatives: OTC Products for Constipation.
  4. Efficacy and Safety of Traditional Medical Therapies for Chronic Constipation: Systematic Review.
  5. Phillips’ Milk of Magnesia.
  6. Chronic constipation.
  7. The Effect of Probiotic Yogurt on Constipation in Pregnant Women: A Randomized Controlled Clinical Trial.
  8. Interventions for treating constipation in pregnancy.
  9. Laxatives, Stimulant (Enema) (Rectal).
  10. Zelnorm® (tegaserod maleate).
  11. Laxatives.
  12. Ask an expert: What’s safe to take during pregnancy?
  13. Pregnancy Constipation.
  14. Milk of magnesia.
  15. MILK OF MAGNESIA- magnesium hydroxide suspension
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