Can I Take Pepto-Bismol with Metformin?

If you experience occasional indigestion, heartburn or upset stomach, chances are you have a bright pink bottle of Pepto-Bismol (bismuth subsalicylate) handy. However, individuals taking metformin to help regulate their blood sugar should speak with a doctor before adding Pepto-Bismol since the combination might result in adverse effects.

Pepto-Bismol and Metformin Interactions: Blood Sugar Fluctuations and Diarrhea

Pepto-Bismol, an over-the-counter antidiarrheal, binds to cells in the lower portion of the esophagus and part of the stomach lining. The protective coating it forms lessens any irritation from stomach acid and may help reduce stomach acid overall. Pepto-Bismol also kills or inhibits the growth of bacteria that can cause diarrhea. Potential side effects of this medication include confusion, dizziness, diarrhea, abdominal pain and black stools.

Metformin, a prescription-based medication, is often prescribed for individuals with high blood sugar caused by type 2 diabetes or gestational diabetes. The drug works by lowering blood sugar through reduced glucose production in the liver and improved insulin sensitivity.

Side effects of metformin can include nausea, vomiting, diarrhea and loss of appetite.

Since both Pepto-Bismol and metformin can loosen bowel movements and result in diarrhea, taking them together might compound that side effect, says Jonathan Jennings, M.D., board-certified internist with Medical Offices of Manhattan.

Additionally, when Pepto-Bismol binds to cells in the stomach, it can potentially impact metformin absorption, says Olga Aroniadis, M.D., chief of gastroenterology and hepatology at Stony Brook Medicine in New York.

“Because the coating can act like a physical barrier, it may potentially reduce contact between metformin and the gastric luminal wall [inner stomach lining],” notes Dr. Aroniadis. She goes on to explain that acidic environments can also affect metformin absorption into the bloodstream. It’s possible for Pepto-Bismol to interfere with absorption due to its impact on the stomach’s acidity.

If metformin isn’t properly absorbed, blood sugar fluctuations are more likely to occur, says Dr. Aroniadis.

While Pepto-Bismol’s drug label does note that individuals prescribed medications for diabetes should consult a physician before taking it, there are no well-documented studies indicating a direct interaction. If you’ve been prescribed metformin, it’s a good idea to talk to your doctor before reaching for that bright pink bottle.

Safer Alternatives to Pepto-Bismol

Some natural alternatives that might help alleviate an occasional mild sour stomach include ginger, peppermint, and chamomile tea.

A bland diet can be followed temporarily to help reduce irritation, adds Dr. Aroniadis.

Tums, an antacid made of calcium carbonate, may offer relief as well. And other antacid medications like Pepcid AC (famotidine) and Prilosec OTC (omeprazole) can be used for short periods to address related symptoms.

Dr. Aroniadis emphasizes that the real concern with using stomach aids, whether natural or over-the-counter, arises when they are used continuously. Persistent gastrointestinal issues may indicate an underlying condition that requires attention. If your stomach discomfort or other intestinal symptoms last more than a day or two, it’s important to talk with your doctor.