H2 Receptor Blockers

H2 receptor blockers—also known as Histamine receptor antagonists (H2RAs)—remain a powerful weapon against gastroesophageal reflux disease (GERD). Antacids such as Maalox, Mylanta, and Tums may provide temporary relief of chronic acid reflux, but they don’t allow an esophagus battered by stomach acid time to heal. That's where the H2 receptor blockers come in.

These medications include: cimetidine (Tagamet HB), famotidine (Pepcid AC), nizatidine (Axid AR), and ranitidine (Zantac 25, Zantac 75 and Zantac 150).

How They Work

Unlike antacids, which neutralize stomach acid, H2 receptor blockers work by thwarting histamine action in parietal cells (cells in the stomach) and reducing acid production by those cells. H2 receptor blockers aren’t as quick to provide relief as antacids, but they grant longer lasting relief so that damaged tissue can heal.

Although relapse rates are high when patients stop taking H2 receptor blockers, healing rates range between 40 to 80 percent, according to the American Gastroenterological Association. The best results are achieved by patients taking higher doses more frequently. Stronger versions of these drugs are available by prescription.


Cimetidine, developed in the 1960s by drug manufacturer Smith, Kline & French (now GlaxoSmithKline) under the brand name Tagamet, may be the world's first blockbuster drug. In addition to GERD, cimetidine is used to prevent or treat heartburn and other syndromes caused by an abundance of stomach acid.

Cimetidine is not only the oldest H2 receptor blocker, it’s also the least tolerated. Some possible side effects include diarrhea, dizziness, and headache. Contact your physician if you experience more serious reactions, such as:

  • blue skin color
  • bruising or bleeding
  • chest tightness
  • serious cough
  • extreme dizziness or unclear thinking
  • fever
  • itching
  • rash
  • seizures
  • swelling of the face, lips, tongue, or throat
  • wheezing


Famotidine was developed by Yamanouchi Pharmaceutical Company and licensed to the drug maker Merck in the 1980s. It’s currently sold under the brand names Pepcidine and Pepcid AC, among others.

Famotidine works in much the same way as cimetidine—by decreasing acid production. It may have similar side effects, too. However, it’s generally better tolerated than cimetidine.


Like famotidine, nizatidine made its debut in the mid-1980s. It’s manufactured by the pharmaceutical company Eli Lilly under the brand name Axid. In addition to GERD, famotidine is used to treat the more serious consequences of the disease, such as erosive esophagitis. It’s generally well-tolerated, although an acute overdose is possible.

Symptoms of an overdose include:

  • fast breathing
  • nausea
  • tremors
  • vomiting

Contact your healthcare provider immediately if you experience any of the above symptoms.


Ranitidine, made by Boehringer Ingelheim, made its debut in the mid-1970s under the brand name Zantac. Like famotidine, ranitidine is used to treat GERD and its more serious consequences. All of the above warnings should be heeded when taking ranitidine.

H2 Receptor Blockers vs. Proton Pump Inhibitors

Researchers analyzing 11 Korean studies conducted between 1997 and 2011 found that people who took popular proton pump inhibitors (PPIs) such as Nexium, Prevacid, and Prilosec had an increased risk of bone fractures when compared to those taking H2 blockers.

Although PPIs are generally considered a superior choice for the treatment of GERD (98 percent of acids blocked versus 70 percent), their downside may be considered a good reason to stick with H2s. For example, scientists noted a 54 percent increased risk of vertebral fractures and a 31 percent increase in hip fractures among those taking PPIs. There was no such increase in those taking the H2 blockers.