Zantac Side Effects

As of June 30, 2024, tumors (benign and malignant) were the most common Zantac (ranitidine) side effects reported to the Food and Drug Administration. The most common types were prostate, colorectal, breast, bladder and renal cancers — accounting for over half of all reported side effects.

Manufacturers pulled Zantac from the market in 2020 after lab tests found N-nitrosodimethylamine (NDMA) contamination in the medication.

“NDMA is a probable carcinogen found in some contaminated ranitidine,” Sazan Sylejmani, pharmacy manager at Westmont Pharmacy in Westmont, Ill., told Drugwatch. “Exposure to high NDMA levels may increase cancer risk. Cancers potentially linked to Zantac and NDMA include colon, breast, stomach and lymphoma.”

Disclaimer: Reports sent to the FDA don’t necessarily mean the drug caused an adverse event. Consult a health care professional before stopping or changing medication.

There was a marked increase in reported adverse events in 2021 and 2022, with these two years accounting for 83% of the total cases reported. This coincides with the timing of Zantac’s withdrawal from the U.S. market.

According to the label for Zantac, data from clinical trials and observational studies showed an excellent safety profile. These studies listed gastrointestinal discomfort and headache as some of the most common side effects. Because the FDA pulled Zantac from the U.S. market in April 2020, there is no new information about side effects from its use.

Zantac FDA Withdrawal

On April 1, 2020, the FDA requested a withdrawal of Zantac and other products containing ranitidine. This was the result of FDA studies showing contamination of Zantac products with NDMA, a probable human carcinogen.

An initial FDA review concluded the levels of NDMA in Zantac were likely too low to cause harm. However, further testing showed that during storage, NDMA levels in Zantac increased to potentially harmful concentrations.

This new data prompted a complete market recall. As a result, the manufacturer Sanofi no longer makes or distributes Zantac.

Common Zantac side effects reported in clinical trials and observational studies include dizziness, headache, constipation and diarrhea. Patients also displayed neurological symptoms including drowsiness and insomnia.

Although these were the most common Zantac side effects, the rate of occurrence was still low.

Most common Zantac side effects are mild and resolve on their own. However, symptoms such as nausea, dark urine and shortness of breath could be signs of a more serious reaction.

In rare cases, patients on Zantac experienced severe side effects, including signs of liver disease or failure. Although these reactions occurred in a small percentage of people taking Zantac, they were sometimes serious or even fatal.

There are rare reports of cardiovascular effects among patients taking Zantac. Irregular heartbeat patterns were the most commonly reported, but other cardiovascular side effects included high blood pressure and extra heartbeats.

Allergic reactions to ranitidine are another rare but possible Zantac side effect. They can cause anaphylaxis, a serious condition that can lead to death. Symptoms of anaphylaxis include a rash or hives; swelling of the face, throat or nasal passages; difficulty breathing and lightheadedness.

Seek medical attention immediately if you experience any anaphylactic symptoms, as failure to do so can be fatal.

Prescribing information warns of rare reports of central nervous system symptoms, including agitation, confusion, depression and hallucinations among patients taking Zantac. These were more common in “severely ill elderly patients.”

Most severe symptoms only occurred with high doses. Usually, they were reversible and subsided away when patients stopped taking Zantac

According to FDA reports, agency testing identified low levels of n-nitrosodimethylamine in Zantac in late 2019. NDMA is a chemical that is reasonably anticipated to be a carcinogen.

On its own, the body produces NDMA at low levels during the digestion of certain foods. However, there is also a risk of overdose from environmental exposure.

In 2020, the FDA requested a complete market withdrawal of Zantac. The agency also urged health care providers to report adverse reactions associated with Zantac and NDMA.

Many patients who developed cancer after taking Zantac filed lawsuits against the manufacturer. Manufacturers settled many of these lawsuits in early 2024.

Researchers continued studying the risks of cancer associated with NDMA in ranitidine-containing drugs. A 2021 study published in the journal Cancers showed a direct association between the use of ranitidine contaminated with NDMA and certain types of gastrointestinal cancer.

On the other hand, other studies did not find a higher cancer risk in Zantac users compared to users of similar drugs.

One especially critical piece, published by the Wall Street Journal, claimed that the NDMA testing for Zantac was conducted under conditions that would never occur in the human body, marking these tests as “junk science.”

After the market withdrawal of Zantac and other ranitidine medicines, many patients turned to several other histamine-2 (H2) blockers and proton pump inhibitors on the market. While these may also cause side effects, they are generally considered safe and effective alternatives to Zantac.

“For Zantac alternatives, options like Pepcid, Tagamet, antacids or lifestyle changes can be effective,” Sylejmani said. “Talk to your doctor or pharmacist to determine the best option for your needs. They can guide you to a safe, effective alternative.”

A newer version of the medication, Zantac 360, contains a different active ingredient, famotidine. This current version of Zantac is only available in over-the-counter strength.

Potential side effects for Zantac 360 using famotidine differ from those listed for the original Zantac with ranitidine.

Editor Lindsay Donaldson contributed to this article.