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Health

3 Potentially Dangerous Supplements Doctors Warn You Should Be Careful With Because They Can Damage Your Digestive System: Iron, More

August 15, 2025 by Mariam Qayum
shefinds | Health
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Supplements are often marketed as quick fixes for energy, weight loss, or overall health—but not all of them are as harmless as they seem. According to doctors, some popular supplements can actually wreak havoc on your digestive system, causing everything from bloating and cramping to more serious long-term gut issues. Here are three potentially dangerous supplements experts say you should approach with caution.

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1. Iron Supplements

Believe it or not, high doses of iron can irritate the digestive tract, leading to common side effects such as constipation, nausea, and stomach pain.

Although iron is important, Michael O. McKinney, MD from Healthy Outlook, says large amounts of it can "lead to an altered flora in the digestive system. Intake of large amounts of iron may promote the growth of pathogenic bacteria, thus resulting in upset stomach, constipation, bloating, and inflammation."

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2. Calcium Carbonate

Another supplement to take cautiously is calcium supplements. Best known for its bone health benefits, they can also cause constipation, bloating, and gas, as they can slow down the digestive process.

McKinney elaborates on this and notes that "calcium is an essential element for the development of bones; however, calcium carbonate supplements produce a constipating effect and may be uncomfortable in the digestive system. This type of calcium is less soluble and may bring disturbances in the intestines, so it becomes difficult for the digestive tract to become healthy."

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3. Magnesium Supplements

Magnesium supplements, especially in higher doses or specific forms like magnesium oxide, can mess up gut health by causing digestive issues such as diarrhea, cramping, and bloating. This could happen because magnesium acts as a laxative by drawing water into the intestines, leading to loose stools and dehydration if taken in excess.

"Too much consumption of magnesium can lead to a laxative effect, causing diarrhea. This can cause an imbalance in the natural gut flora and irritate the gastrointestinal tract, leading to discomfort and disrupting digestive health," says Dr. Kubanych Takyrbashev, MD, Health & Wellness Advisor at NAO.

Author:

Editorial Assistant

Mariam is an Editorial Assistant and writer at SheFinds, covering everything from style and beauty to health and wellness. Splitting her time between New York and Philadelphia, she brings a sharp eye for trends and a passion for storytelling to the digital space. With a strong editorial background, she’s always exploring the latest in fashion, skincare, and wellness. When she’s not writing or pitching, you’ll find her in the kitchen experimenting with new recipes or planning her next travel adventure. You can reach Mariam at mariam@shefinds.com.

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Pouring vitamin D into palm for health benefits.
Comparing cooking spray and olive oil for healthy cooking.
Image from SHEfinds
Colorful Brazilian dish featuring rice, beans, and chicken.
Image from SHEfinds
Checking time on watch during breakfast meal.
Image from SHEfinds
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Display of deli meats, sandwiches, hot dogs, and sausages.
Image from SHEfinds
Cooked salmon served with rice, avocado, and greens.
Woman taking magnesium supplement for health.
Grilled chicken breast with fries, salad, and dipping sauces.
Image from SHEfinds
Frozen pizza available in grocery store freezer aisle.
Fried fish served with crispy fries on plate.
Image from SHEfinds
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Spilling vitamin C pills into hand for daily intake.