Last Updated on April 25, 2026 by Beth Skwarecki
Yes, Mylanta can cause diarrhea. I would say this is one of the most common digestive side effects, especially in people who are sensitive to magnesium. Magnesium hydroxide in Mylanta can pull water into your intestines and make stool looser.
For some people, that means softer stool. For others, it can mean diarrhea.
Why Mylanta Can Cause Diarrhea
Mylanta often contains magnesium hydroxide, which is the ingredient most likely to cause diarrhea.
Magnesium can pull water into the intestines. More water in the stool can make bowel movements softer, looser, and more frequent.
Your body may react more strongly if you take too much Mylanta or already have a sensitive digestive system.
How Common Is Diarrhea With Mylanta
Diarrhea is not guaranteed, but it is common enough to be one of the better known Mylanta side effects.
Some people notice only one loose bowel movement. Others may have repeated bathroom trips after taking it.
Your reaction often depends on your dose, your stomach sensitivity, and how often you use it.
Is Diarrhea After Mylanta Normal
Mild diarrhea after Mylanta can happen and is often linked to the magnesium in the formula.
I would be more concerned if diarrhea is severe, lasts more than a day or two, or comes with weakness, dehydration, vomiting, fever, or blood in stool.
What You Can Do
If Mylanta causes diarrhea, check your dose first. Taking more than directed raises the chance of bowel side effects.
You may also want to pause use and review our full guide on Does Mylanta Make You Poop to see why the formula affects bowel movements.
Bottom Line
Mylanta can cause diarrhea because magnesium hydroxide can loosen stool. Mild symptoms may improve quickly. Strong or repeated diarrhea should be checked by a healthcare professional.
Beth is Cloudmineinc’s senior health editor and a certified personal trainer. She has over 10 years experience as a science journalist and is the author of two books. She deadlifts over 315 lbs.