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Zantac Side Effects

Common side effects of Zantac (ranitidine) include headaches, diarrhea and nausea. These side effects are mild and temporary. Rare, serious Zantac side effects include liver failure, acute porphyria attacks in patients with acute porphyria and pneumonia.

Last Modified: March 21, 2024
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What Are the Common Side Effects of Zantac (Ranitidine)?

Zantac made with ranitidine is no longer available on the U.S. market. The market withdrawal doesn’t affect Sanofi’s new Zantac 360 made with famotidine, and the information about side effects on this page is specifically for Zantac made with ranitidine.

The most common side effects of Zantac are mild and infrequent. They also don’t last very long. Because ranitidine is no longer available on the market, there is no new information on Zantac made with ranitidine and its side effects.

Zantac side effects may include:
  • Stomach pain
  • Constipation
  • Diarrhea
  • Headache
  • Drowsiness
  • Fatigue
  • Dizziness
  • Insomnia
  • Nausea
  • Vomiting
  • Rash
  • Dark urine
  • Shortness of breath
  • Chest pain
  • Jaundice
  • Fever

In clinical trials, the rate of Zantac side effects was very similar to those reported by people who took a placebo, or an inactive medicine, according to French researchers who published their work in Drug Safety.

Researchers in another study by Glaxo Wellcome looked at data from controlled clinical trials with more than 26,000 patients who took the drug for four weeks or more. They also looked at postmarketing surveillance studies and adverse event reports. Researchers “confirmed the excellent safety profile of ranitidine.”

But after the Valisure pharmacy alerted the FDA that batches of ranitidine contained high levels of N-nitrosodimethylamine, or NDMA, several manufacturers voluntarily recalled their ranitidine products.

On April 1, 2020, the FDA requested manufacturers immediately withdraw all prescription and over-the-counter ranitidine drugs from the market. While initial FDA testing found NDMA in ranitidine in low levels, new FDA testing confirmed that NDMA levels increase in ranitidine over time.

Woman with a headache
Headache is the most common ranitidine side effect reported in clinical trials.

Serious and Rare Zantac Side Effects

According to the drug’s insert, serious Zantac side effects are rare. If you suffer any of the following side effects, talk to your health care provider.

Serious side effects of Zantac (ranitidine) include:
  • Clay-colored stools
  • Coughing up mucus
  • Dark urine
  • Easy bruising or bleeding
  • Irregular heartbeat
  • Loss of appetite
  • Severe blistering, peeling, and red skin rash with headache
  • Vision problems
  • Weakness
  • Yellowing of the eyes or skin

Central Nervous System

Rare cases of mental confusion, depression, agitation and hallucinations and reversible blurred vision have been reported. These mental issues have been reported most often in severely ill, elderly patients. Some people also reported vertigo, dizziness and involuntary motor disturbances.

Cardiovascular Side Effects

Cardiovascular issues with Zantac are extremely rare but have occurred. French researcher T. Vial and colleagues reported the risk was about 1 in 1 million patients.

These include abnormal heart rhythms that mostly occur during rapid intravenous treatment with ranitidine. They usually subside after stopping the drug. Other cardiac events include hypertension and premature ventricular beats.

Gastrointestinal Issues

Along with constipation, diarrhea and abdominal pain, researchers also received rare reports of pancreatitis.

Liver Failure and Hepatitis

People have reported rare instances of liver failure and hepatitis. Some of these people also suffered jaundice. If this happens, discontinue Zantac immediately and speak to a health care professional. According to the drug’s label, these conditions are usually reversible. In rare cases, people died because of liver injury.

Blood Disorders

Some people who took Zantac suffered blood count changes including low white blood cells and low platelets. Rare cases of low red blood cell counts, with or without bone marrow problems, and very rare cases of acquired immune hemolytic anemia have been reported.

Gynecomastia, Impotence and Decreased Sex Drive

According to the drug’s label, controlled studies in animals and humans didn’t show that Zantac caused impotence or abnormal enlargement of the breasts called gynecomastia. But men taking the drug have reported cases of impotence and decreased sex drive when taken at high doses for a long period of time. These were comparable to the general population.

Both males and females have reported rare instances of gynecomastia and galactorrhea, a milky nipple discharge.

How Often Do Serious Side Effects Occur?

Researcher J.G. Mills and colleagues reported on rare, serious side ranitidine effects and how often they occurred out of almost 24,000 people in clinical trials. Only about 1.65 percent of people suffered serious reactions.

Frequency (%) of Serious Side Effects in 23,672 People
  • Abdominal pain 0.13
  • Nausea and vomiting 0.08
  • Hemorrhage 0.09
  • Chest pain 0.05
  • Pneumonia 0.05
  • Headache 0.06
  • Malaise/fatigue 0.04
  • Ischemic heart disease 0.06
  • Cardiac infarction 0.03
  • Lung neoplasm 0.01
  • Hypertension 0.04
  • Phlebitis (inflammation of a vein) 0.01
  • Backache 0.04
  • Mental disorder 0.08
  • Renal problems 0.07
  • Skin and soft tissue problems 0.08
  • Injury and poisoning 0.05
  • Infectious disease 0.02
  • Cerebrovascular disease 0.04

NDMA Contamination Side Effects

NDMA is a chemical that was once used in the production of rocket fuel, lubricants and other industrial products. It is also found in small amounts in food, soil, air and water and is a byproduct of water chlorination, according to the Environmental Protection Agency.

The chemical is known to cause cancer in animals and may cause cancer in humans. Some people who developed cancer filed lawsuits against Zantac drugmakers. The main cancer in Zantac lawsuits is bladder cancer, but other cancers such as stomach cancer, colon cancer, prostate cancer, kidney cancer, liver cancer and breast cancer have been linked to NDMA.

The EPA lists several symptoms of overexposure to NDMA.

Potential Side Effects of NDMA Toxicity
  • Abdominal cramps
  • Diarrhea
  • Enlarged liver
  • Fever
  • Headache
  • Jaundice
  • Nausea
  • Reduced function of liver, kidneys and lungs
  • Vomiting

The FDA has determined the safe dietary daily intake limit for NDMA consumption is 96 ng. In September 2019, the pharmacy Valisure told the FDA that it had tested brand name and generic Zantac and found NDMA levels as high as 3,267,968 ng per tablet.

According to Valisure, ranitidine contains molecules that may actually create NDMA when exposed to conditions that mimicked the human stomach.

In December 2019, the FDA announced it had not found that ranitidine forms NDMA in typical human stomach conditions. The agency told manufacturers to test all batches of ranitidine and instructed them not to sell batches that contain NDMA levels over 96 ng.

However, further FDA testing and evaluation confirmed that NDMA levels increase in ranitidine under normal storage conditions and especially when stored at higher temperatures, such as those during distribution and consumer handling. And the older the ranitidine product is, the greater the level of NDMA, the FDA found.

“These conditions may raise the level of NDMA in the ranitidine product above the acceptable daily intake limit,” the FDA said in an April 1, 2020, news release.

As a result, the FDA requested immediate market withdrawal of all ranitidine products, meaning neither new nor existing prescription or OTC ranitidine products will be available for use in the U.S.

Is Zantac Safe for Pregnant Women and Children?

In general, Zantac is safe for pregnant women and children. But researchers have not established safety and effectiveness in babies less than one month old in clinical trials, according to ranitidine’s medication label.

Zantac and Pregnancy
The FDA categorized Zantac as Pregnancy Category B. This means it is unlikely to affect an unborn baby. But mothers-to-be should talk to their health care providers about whether they should use it during pregnancy or breastfeeding.


In animal studies, researchers administered doses up to 160 times the human dose to rabbits and rats and found no evidence of harm to the fetus or fertility. But there have been no tests in pregnant women. The drug label recommends using the drug with caution and only if clearly needed.

Because ranitidine can travel through breast milk, nursing mothers should use caution.

Children and Babies

Zantac side effects in children one month to 16 years of age are similar to those found in adults, according to clinical trial data on the drug label.

Studies have previously shown that acid-reducing drugs such as Zantac are well tolerated by babies.

But emerging evidence suggests gastric acid inhibiting drugs may increase the risk of infections, bacterial overgrowth and other problems in children and babies, according to a study published by Mark Safe and colleagues in World Journal of Gastrointestinal Pharmacology and Therapeutics.

Before Taking Ranitidine

Ranitidine is generally safe, but not everyone should take it. People with preexisting conditions or who take certain medications should talk to their health care provider before taking the drug. Before taking ranitidine, tell your health care provider or pharmacist about any medical conditions you have or medications you take.

Warnings and Precautions
  • Tell your health care provider if you are allergic to ranitidine or any of the drugs in the same class called H2 blockers.
  • Tell your health care provider about all the medication, vitamins and supplements you take, especially if you take blood thinners such as warfarin. You may need to adjust your dose.
  • Tell your health care provider if you have ever had kidney or liver disease, phenylketonuria or porphyria. Zantac may trigger an acute porphyria attack.
  • Tell your health care provider if you have chest pain that isn’t like typical heartburn pain, especially if it is accompanied by nausea, sweating or dizziness. These symptoms could mean a heart problem.

Long Term Use & Withdrawal

In general, Zantac is safe for long-term use. But drugs that affect acid production like H2 blockers and proton pump inhibitors may affect how some vitamins like B12 are absorbed. A B12 deficiency can lead to anemia, dementia, neurological damage and other problems, some of which are irreversible.

A study by researcher Jameson R. Lam and colleagues found that people who took H2 blockers like Zantac for two or more years were more likely to have B12 deficiency than those who did not. The effect was greater in people who took proton pump inhibitors.

Zantac Withdrawal
People who used 300 mg of ranitidine for two months suffered indigestion that lasted about two days after stopping treatment.

Research has also tied long-term use of Zantac to withdrawal symptoms, mainly indigestion.

One study by British researcher A.D. Smith and colleagues found that people who used 300 mg of ranitidine for two months suffered indigestion after stopping treatment. The symptoms lasted for about two days on average and were the most severe on the second day after stopping the drug.

Please seek the advice of a medical professional before making health care decisions.