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Acid Reflux

Side Effects of H2 (Histamine) Blockers – Are You Signing Up For Heart Palpitations and Osteoporosis?

Jul 24, 2017

Rebecca has been suffering from acid reflux for a long time. Because she didn’t find much relief from the proton pump inhibitors she was taking earlier, her doctor advised her to try ranitidine. With these tablets, she experienced relief from acid reflux like never before. And did she mention this drug was cheaper than her earlier drug? Yes, it was.

As a result, whenever she experienced heartburn, Rebecca popped a ranitidine tablet and experienced relief almost immediately. Soon after starting to take this medicine regularly, she started experiencing heart palpitations. She felt dizzy and almost fainted a couple of times. One frightening morning, she experienced severe chest pain, as if a giant hand was pressing hard against her chest.

Rebecca’s experience, though dramatic, isn’t improbable. If she continues with these drugs for long, she may be at a serious risk of weakened bones and painful limbs.

Many doctors prescribe “H2 Receptor Blockers” (or H2 antagonists) to treat the symptoms of GERD. Ranitidine is one drug, which belongs to the group of H2 blockers. These medications reduce the amount of stomach acid in the stomach. Sadly, acid suppression for relieving acid reflux is a bad idea and does more harm than good.

Gastroesophageal reflux disease, or GERD, if not controlled properly, may lead to peptic ulcers and gastritis (inflammation of the stomach lining). H2 antagonists are also prescribed to treat these conditions or to prevent them from recurring. Research shows that while H2 blockers are effective in relieving symptoms of acid reflux, they also carry the risks of cardiovascular problems and osteoporosis in patients.

How do H2 Blockers Work Inside the Body?

Special cells in the stomach lining, called parietal cells, secrete acid inside the stomach. Histamine is the most important of the three regulatory molecules that directly activate the parietal cells to secrete acid. Histamine acts on the parietal cells by binding to special receptors on their surface. These receptors are known as H2 receptors. Anything that blocks histamine from binding to its receptor will negatively impact acid secretion. This is exactly what H2 antagonists do. These chemicals have a structure similar to histamine and compete with it for binding to the H2 receptors. In their presence, histamine is unable to bind to the receptors and cannot activate acid secretion.

Most Prescribed Names in this Category:

H2 receptor blockers fall under four classes –

  • Famotidine (Pepcid)
  • Cimetidine (Tagamet)
  • Ranitidine (Zantac, Gavilast)
  • Nizatidine (Axid)

How H2 Blockers Are Taken Usually?

H2 receptor blockers are available as tablets, capsules or liquids. People often take them with the first meal of the day. Many doctors prescribe either taking a dose with the evening meal or a second dose in the evening. They take around 30 to 90 minutes to work and may provide symptomatic relief for several hours.

Side Effects That Could Happen As Soon As You Start Taking the Medication

H2 receptor blockers are pretty well tolerated and only about 3% of individuals experience minor side effects like headaches, diarrhea and fatigue. Other side effects of histamine blockers include

  • Abdominal pain
  • Confusion
  • Coughing or difficulty swallowing
  • Bleeding or crusting sores on lips
  • Blistering of skin
  • Irregular heartbeat
  • Wheezing
  • Chest tightness
  • Hallucinations
  • Runny nose, and
  • Trouble urinating, among others

What Can You Do To Reduce the Side Effects of H2 Blockers?

If you are among the 3% of people who experience immediate side effects after taking H2 blockers, your doctor may either change the class of the drug (remember, there are 4 classes of this drug), reduce the dosage or reduce the frequency of the drug.

Should You Be Taking H2 Blockers for a Long Term?

side effects of Histamine blockers

Should You Be Taking H2 Blockers for a Long Term?

Studies have shown that H2 receptor blockers carry a substantial risk of cardiovascular diseases. A study found that H2 receptor blockers can cause bradycardia (abnormally slow heart action). The participants of this study started showing symptoms of slow heart action within just a week of starting cimetidine and ranitidine.

Another study made a startling observation that H2 blockers negatively influenced heart rate variability, by interfering with its natural rhythm. Heart rate variability is a measure of the fine balance between the two branches of the autonomic nervous system. Fluctuating heart rate variability is a sign of an impending heart attack. This means that people who take H2 blockers are at a major risk of a heart attack.

A study found that famotidine had a negative inotropic effect (an effect capable of weakening the force of muscular contractions.) And guess which organ works exclusively through on its muscular contractions? You guessed it right! It’s the heart.

High doses of cimetidine (>5g/day) can cause impotence and “gynaecomastia” (enlargement of male breast tissue). Cimetidine interferes with removal of toxic compounds from the body, which can lead to potentially damaging consequences for the body.

Long term acid suppression using H2 blockers can also cause an imbalance in the normal gut microflora (bacterial populations in the gut). This can cause overgrowth of harmful bacteria and reduction in helpful bacteria. This imbalance can negatively impact immune status. Long-term acid suppression can also lead to gastric malignancy (stomach cancer).

Decrease in stomach acidity also impairs the digestive system’s ability to absorb calcium. Since H2 blockers reduce the ability of the stomach to produce adequate amounts of acid, they interfere with calcium absorption. This may lead to lower bone mineral density, leading to weak bones. Therefore, long-term users of H2 blockers carry a risk of osteoporosis.

Special Precautions While Taking H2 Blockers

Cigarette smoking decreases the effect of H2 blockers. Hence, you should quit smoking if you are taking this medication. While you are on H2 blockers, you shouldn’t be consuming alcohol as the drug tends to increase the blood alcohol levels that may be potentially harmful.

Sufficient studies have not been done on the effect of these drugs on the fetus during pregnancy. If you are pregnant, you need to weigh the risk-benefit ratio of taking any drugs, not just H2 blockers. Nursing mothers, however, should not take H2 blockers while they are breastfeeding as the medicine may pass on to the baby along with breast milk and cause unwanted decrease in stomach acidity.

People with a weakened immune system should also take H2 blockers with caution as decrease in stomach acid caused by H2 blockers may increase the risks of certain types of infections.

What If I Forget a Dose?

For best results, these medicines need to be taken with meals and/or at bedtime. If you miss a dose, take it as soon as you remember it. If it is already time for your next dose, take the regular dose and do not take a double dose.

Storage and Disposal of the Medication

Store the medications in a closed container at room temperature away from heat, direct light and moisture. Do not store in the bathroom or in the refrigerator. Keep away from the prying hands of children. Dispose expired medicines with care.

Dietary Considerations

Certain foods and drinks will make your GERD worse. These include citrus products, sodas and spicy foods. When you are suffering from GERD, it is better to stay away from such foods, so that you do not inflame your stomach anymore and do not impair the action of the medication you are taking.

Drug Interactions

H2 blockers reduce stomach acidity. So any drug that requires higher stomach acidity for its activity will lose its efficacy if taken along with H2 blockers. H2 blockers antagonize histamine. Therefore, histamine will lose its efficacy if taken along with H2 blockers. There are many other drugs that interact with H2 blockers; caution is advised while taking them along with an H2 blocker.


Tablets of H2 blockers will contain one of the four active compounds mentioned above (e.g. cimetidine) along with neutral substances like microcrystalline cellulose, magnesium stearate, titanium dioxide, hypromellose, pregelatinized starch, yellow iron oxide, dimethicone, polysorbate 80 and glycerol triacetate, among others. Some brands also add aspartame as a sweetener.

Final Verdict

Americans spend billions of dollars on heartburn medicine and yet hardly anybody bothers to address this problem at its root. Suppressing heartburn for a few hours of relief is like gradually pushing your body over the edge. Your heartburn may be telling you that something far worse is happening inside. Every discomfort in the body is its way to signal an underlying problem. The key is to listen to what your body is trying to tell you.

The growing popularity and the ease with which people have access to medicines like H2 receptor blockers is putting millions at risk of potentially fatal side effects. Even doctors agree that these, and other heartburn drugs, are being overused unnecessarily. Another truly alarming statistic is that around 60% to 80% of patients who are prescribed conventional heartburn medicines are done so inappropriately. Add to this the equally shocking fact that only around three in 10 doctors truly understand how to prescribe heartburn medications like H2 blockers (since these medications are meal-activated, they have to be taken with food for them to work properly). And what’s worse, only 10% patients follow this advice.

Acid reflux is a disorder of bodily imbalance. A proper diet supported by a complementary lifestyle is sure to correct this imbalance. H2 blockers are okay to be prescribed for a short period and for complications, which require suppression of stomach acid. But unconstrained use of this and other potent medications can be harmful in the long term.

Jitendra Rathod
Jitendra is a microbiologist and a passionate student of the human body. He is a firm believer in the power of alternative and holistic medicine. He believes nature holds the key to restore us back to health and balance.