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Zantac Side Effects

Most people tolerate Zantac well, and its common side effects, including headaches, diarrhea and nausea, are mild and temporary. On rare occasions, some people have reported serious problems such as liver failure, acute porphyria attacks in patients with acute porphyria, and pneumonia. In April 2020, the U.S. Food and Drug Administration requested manufacturers remove all ranitidine products from the market over concerns of contamination with NDMA, a chemical that can cause cancer.

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.”

In studies, Zantac has been shown to be effective and safe for most people.

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.

Headaches, Stomach Pain and Other Common Side Effects

Most people don’t experience side effects with Zantac, and the most commonly reported side effects for Zantac are mild and infrequent. They also don’t last very long.

The most reported side effects from clinical trials are headaches, tiredness, dizziness and mild gastrointestinal issues such as constipation, diarrhea and nausea.

A search for generic ranitidine and brand name Zantac at different dosages in the FDA Adverse Event Reporting System, or FAERS, from 1982 to June 30, 2020, revealed a total of 74,285 adverse event reports. However, according to the U.S. Food and Drug Administration, FAERS data has its limitations. Because it is a voluntary reporting system, the FDA cannot be sure the medication actually caused the side effects.

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

Overall, database reports of adverse events for Zantac and its generics appear to be limited.

In 2018, there were over 25 million prescriptions for ranitidine, according to Bloomberg Intelligence data. But only 4,103 adverse events were reported in FAERS for generic and brand name Zantac in the same year.

The most commonly reported side effects in FAERS are consistent with clinical trials. These include headache, diarrhea, nausea, indigestion, vomiting, dizziness, abdominal pain and pruritus, or itchy skin.

Common Side Effects
  • Constipation
  • Diarrhea
  • Nausea
  • Vomiting
  • Stomach pain
  • Headache

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.

Serious and Rare Side Effects

According to the drug’s insert, serious Zantac side effects are rare. Of the total 55,834 adverse-event reports from 1982 to Sept. 30, 2019, serious events accounted for 23,557 — including 2,175 deaths.

If you suffer any of the following side effects, talk to your health care provider.

Serious Side Effects
  • 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 Loss of 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 loss of sex drive. 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

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.

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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 bladder and stomach cancer filed lawsuits against Zantac drugmakers.

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.

Zantac Side Effects Facts
  1. Most Common Side Effects Headaches, diarrhea, vomiting, nausea and other gastrointestinal issues
  2. Rare, Serious Side Effects Liver problems, acute porphyria, skin rashes and pneumonia
  3. Pregnancy Rating Category B – Animal studies have not demonstrated a risk to the fetus, but there are no adequate studies in pregnant women
  4. NDMA Contamination Rare possible side effects from NDMA overexposure include liver problems, nausea, vomiting, fever and abdominal cramps

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

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Michelle Llamas, Senior Content Writer
Written By Michelle Llamas Senior Writer

Michelle Llamas has been writing articles and producing podcasts about drugs, medical devices and the FDA for seven years. She specializes in fluoroquinolone antibiotics and products that affect women’s health such as Essure birth control, transvaginal mesh and talcum powder. Michelle collaborates with experts, including board-certified doctors, patients and advocates, to provide trusted health information to the public. Some of her qualifications include:

  • American Medical Writers Association (AMWA) Engage Committee and Membership Committee member
  • Centers for Disease Control and Prevention (CDC) Health Literacy certificates
  • Original works published or cited in The Lancet, British Journal of Clinical Pharmacology and the Journal for Palliative Medicine
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23 Cited Research Articles writers follow rigorous sourcing guidelines and cite only trustworthy sources of information, including peer-reviewed journals, court records, academic organizations, highly regarded nonprofit organizations, government reports and interviews with qualified experts. Review our editorial policy to learn more about our process for producing accurate, current and balanced content.

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