People suffering from heartburn walk a fine line. While popular heartburn medications like Nexium and Prilosec might provide relief, studies reveal the drugs also cause debilitating and potentially life threatening side effects. Unfortunately for many heartburn drug users, stopping these medications can cause even worse symptoms. Patients are struggling to find the balance between relief and risk.

A new study published in the Journal for the American Medical Association (JAMA) Oncology found heartburn drugs actually reduced the effectiveness of treatments for gastroesophageal cancer. Specifically, PPIs reduced the efficacy of the chemotherapy drug capecitabine.

Capecitabine is administered orally to treat a variety of colon cancers. However, because it is administered orally, there is a greater risk of drug interaction before the drug can enter the bloodstream.

In addition to compromising the efficacy of cancer treatments, heartburn medications can also react with antibiotics to cause arrhythmia, or an unusual heartbeat. Arrhythmia can cause dizziness, chest pain, fainting, and shortness of breath, but it can also be life threatening if left untreated.

Drugs like Nexium and Prilosec can also cause a condition called rhabdomyolysis, the rapid breakdown of muscle tissue, which releases myoglobin into the bloodstream. Rhabdomyolysis can cause a loss of kidney function and/or complete kidney failure requiring dialysis treatment or a complete kidney transplant.

The drugs can also cause an intestinal infection called Clostridium Difficile, more commonly known as C. diff. This infection can cause patients to experience as many as 40 bowel movements a day and can be life threatening if not treated.

But the side effects of Nexium and Prilosec don’t end there. The drugs have also been found to cause osteoporosis, when bones become weak and brittle. This puts patients taking PPIs at a higher risk of fracturing bones.

Side effects from Nexium and Prilosec can be incredibly severe, and because these drugs are available over the counter, millions of Americans unknowingly expose themselves to much greater risks.