Last Updated on April 25, 2026 by Beth Skwarecki
Mylanta can cause side effects, but most are mild and affect digestion. I would say the most common ones are diarrhea, loose stool, nausea, constipation, and stomach discomfort. Your side effects often depend on which ingredient your body reacts to most.
Some people react more to magnesium and notice loose stool. Other people react more to aluminum and feel constipated. Most mild side effects improve after you stop taking it.
Common Mylanta Side Effects
Mylanta is used for heartburn, gas, and indigestion, but it can also affect digestion in ways you may not expect.
Common side effects may include
- loose stool
- diarrhea
- constipation
- nausea
- stomach cramps
- bloating
- chalky taste
- mild upset stomach
I would pay attention to how your stomach feels after each dose because small changes can tell you how your body handles the formula.
Why Mylanta Causes Side Effects
Mylanta side effects usually come from its active ingredients. Many products contain magnesium hydroxide, aluminum hydroxide, and simethicone.
- Magnesium hydroxide can loosen stool and trigger diarrhea.
- Aluminum hydroxide may slow digestion and cause constipation.
- Simethicone helps gas pass more easily, but it may also change how your stomach feels for a short time.
- Your body may tolerate one ingredient well and react more strongly to another.
Most Common Digestive Side Effects
Digestive side effects are the most common with Mylanta. You may notice loose stool, constipation, gas movement, cramping, or a sudden need to use the bathroom.
If your main concern is bowel changes, read our guide on Does Mylanta Make You Poop to understand why this happens.
Less Common But Serious Side Effects
Serious side effects are less common, but they can happen.
You should get medical help if you notice
- severe diarrhea
- severe stomach pain
- black stool
- bloody stool
- vomiting blood
- chest pain
- trouble swallowing
- weakness
- dehydration
- confusion
I would not ignore these symptoms because they may point to something more serious than simple indigestion.
Who Is More Likely To Have Side Effects
You may be more likely to notice Mylanta side effects if you
- take higher doses
- daily Mylanta use
- have kidney disease
- take multiple medicines
- have a sensitive stomach
- already deal with diarrhea or constipation
Your risk may also be higher if you use Mylanta often without checking the label or dose.
Can Mylanta Interact With Other Medicines
Yes, Mylanta can affect how some medicines are absorbed.
I would be careful if you take
- antibiotics
- thyroid medicine
- iron
- blood pressure medicine
- prescription stomach medicine
A pharmacist can help you space doses safely.
When To Stop Taking Mylanta
You should stop taking Mylanta and ask a healthcare professional if side effects feel strong, unusual, or keep happening.
Mild side effects often improve once the product leaves your system. Severe or repeated symptoms should not be ignored.
Bottom Line
Mylanta side effects are usually mild and often affect digestion. Your most likely issues are diarrhea, loose stool, constipation, and stomach discomfort. If symptoms feel severe or unusual, you should stop using it and speak with 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.