Stomach Acid Issues? Know the Possible Outcomes of Taking H2 Blockers

H2 blockers, also known as histamine H2 receptor antagonists or H2RAs, are a class of drugs commonly used to treat moderate acid-related gastrointestinal disorders. They work by blocking the production of stomach acid, which relieves the symptoms of conditions such as heartburn.

When histamine binds to a receptor, it acts as a secretagogue. A what? Basically, it stimulates the release of stomach acid. By binding to the histamine-2 receptors, H2 blockers reduce the secretion of stomach acid.

How do H2 blockers relieve symptoms?

H2 blockers are considered generally safe and effective and may help relieve the symptoms and promote the healing of several GI issues.

Peptic ulcers

Before the advent of H2 blockers, peptic ulcers—sores on the inner lining of the stomach or upper part of the small intestine—were considered a life-threatening condition with poor long-term outcomes. Common symptoms of peptic ulcers may include abdominal pain, bloating and nausea. In severe cases, patients may vomit blood or pass dark stools, at which time they should consult a medical professional.

Gastroesophageal reflux disease (GERD)

GERD is a chronic digestive disorder characterized by the frequent reflux of stomach acid into the esophagus. Common GERD symptoms include regurgitation, difficulty swallowing and chest pain.

Gastritis

Defined as inflammation or irritation of the stomach lining, gastritis can be acute or chronic. The condition could be triggered by an infection with the bacterium Helicobacter pylori, the excessive use of nonsteroidal anti-inflammatory drugs (NSAIDs), excessive alcohol consumption, stress or certain autoimmune disorders.

What are the types of H2 blockers?

H2 blockers are available in different formulations and dosages. Some are available over the counter and others require a prescription from a healthcare provider. They are typically taken orally, and the effects and duration of action may vary from person to person.

Cimetidine (brand name Tagamet) was the first H2 blocker to be introduced in the marketplace and has been used for many years. It has been largely replaced, however, by other H2 blockers due to its interactions with other drugs that may cause severe side effects.

Famotidine (Pepcid) is the most potent H2 blocker. It offers a longer duration of action and is less likely to cause adverse side effects or disrupt other medications. Similar in potency and duration of action to famotidine, nizatidine (Axid) is not as widely used and is typically only available with a prescription.

Ranitidine (Zantac) is a popular H2 blocker that has been withdrawn from the market in many countries due to carcinogen-related concerns.

"In March 2020, the Food and Drug Administration requested the immediate removal of Zantac, or ranitidine, off the market," said Semiya Aziz, M.B.B.S., a general practitioner in the United Kingdom, adding it was discontinued due to its link to an increased risk of cancer in animals.

Research has found evidence on this matter is lacking and more studies are being conducted.

Ranitidine is not currently available globally, Aziz said. Other brands of H2 blockers, such as cimetidine, famotidine and nizatidine, continue to be prescribed.

However, these have now been superseded by proton pump inhibitors, such as lansoprazole (Prevacid), omeprazole (Prilosec) and esomeprazole (Nexium).

Drug interactions

Generally known to be safe and well-tolerated, H2 blockers can cause side effects in some people. Some of the most common side effects include:

• Headache
• Dizziness
• Constipation
• Diarrhea 

In some cases, H2 blockers may cause more serious side effects. People who have preexisting medical conditions are more susceptible, as are those taking other medications that don't interact well with H2 blockers.

"There are multiple drug interactions. You need to be careful, as H2 blockers can affect the absorption of other drugs, such as blood thinners and anti-epilepsy medication," said Abbas Kanani, M.R.Pharm.S., the resident pharmacist at Chemist Click, an online pharmacy in the U.K. "You should always check with your doctor or pharmacist beforehand."

Side effects may occur if the H2 blockers are taken in conjunction with a form of medication that relies on an acidic stomach environment. For example, cimetidine has been observed to cause side effects in people receiving treatment for kidney or liver problems.

The following groups of people should always speak to their doctor before starting medication:

• People older than age 50
• Patients with kidney problems
• People with hepatic impairment
• Women who are breastfeeding or pregnant
• Individuals taking medications that could potentially interact with these drugs

Could H2 blockers trigger hormonal abnormalities?

H2 blockers, to reiterate, are generally safe and effective. Even so, keep in mind they could potentially trigger hormonal abnormalities and result in negative sexual health outcomes.

Some studies have suggested that long-term use of H2 blockers may reduce testosterone levels in men. This can lead to erectile dysfunction (ED) and gynecomastia (enlarged breasts in men). Hormonal abnormalities have also been observed in women in the form of galactorrhea, where the breasts produce milk unrelated to pregnancy.

Long-term use of H2 blockers may interfere with the absorption of vitamin B12. Lack of B12 can lead to anemia and some neurological issues. This is typically only a concern for people who take H2 blockers for a period of 12 months or more. In general, experts do not recommend self-treatment with H2 blockers for a long period of time.

Myths and misconceptions about H2 blockers

They've been used for a long time for conditions such as heartburn and peptic ulcers, but a number of myths persist about this type of drug.

Myth: H2 blockers are addictive

"A common misconception is that H2 blockers are addictive, which is not true. They do not cause physical dependence or withdrawal symptoms," Kanani said.

Myth: H2 blockers can cure acid reflux disease

"Some may also believe that they are a cure for acid reflux disease, and although they can help to relieve symptoms of acid reflux disease, they do not cure the condition," Kanani said. "Acid reflux disease is a chronic condition that requires ongoing management and lifestyle changes."

Myth: H2 blockers are not safe for long-term use

"When taken as directed, they are generally safe for long-term use," Kanani said. "There have been reports linking long-term use of H2 blockers with bone fractures in elderly patients, however, recent research shows that these claims are not substantiated."

Myth: You won't be able to digest food if you take a drug to suppress acid

"Our bodies naturally produce acid that helps break down food in the stomach and kills harmful bacteria. Acid works together with other substances in the stomach called enzymes to break down food," Aziz explained. "H2 blockers reduce the amount of acid but don't completely inhibit acid from being produced, hence, digestion still continues.

Studies have suggested that the decrease in stomach acid affects the body's ability to absorb vitamins B12 and D, folate, iron, zinc and some other nutrients, he added. As such, extra supplementation may be needed.

"Those who take H2 blockers and magnesium supplements should do so at different times of day to reduce the risk of interactions," Aziz said.

Talk to a medical professional about H2 blockers

Overall, H2 blockers are touted for their safety and efficacy, and no irreversible side effects are associated with taking these drugs. Any studied side effects have subsided upon discontinuation of the medication.

Be cautious with long-term use, self-treatment and taking the drugs in a way that's not directed. Also, don't take them in combination with other medications without seeking professional advice.

It is important to use H2 blockers responsibly and under the direction of your doctor or pharmacist, lest gastric issues arise. Individuals taking H2 blockers long term should also be aware of rare potential impacts on their sexual health and hormonal abnormalities, such as reduced testosterone levels.

Questions or concerns about GI issues? Talk to a medical professional who can take your history and evaluate your situation. If you don't have a doctor you see regularly, telehealth makes it easy to connect with one.

Giddy Telehealth is an easy-to-use online portal that provides access to hundreds of healthcare professionals whose expertise covers the full scope of medical care. Many of them offer same-day video visits.