Medicines for GERD: antacids, alginates, H2 blockers and PPIs explained

Reflux medicines range from antacids you can buy anywhere to prescription acid blockers. This guide explains how each type works, when it is most useful and what to be aware of, so you can have a better-informed conversation with your pharmacist or doctor.

The treatment ladder

GERD is usually treated step by step, using the least intensive option that controls symptoms:

1. Lifestyle and diet changes: the foundation for everyone. See lifestyle changes.
2. Antacids and alginates: for occasional symptoms, taken as needed.
3. H2 blockers: reduce acid production for several hours.
4. Proton pump inhibitors (PPIs): the most effective acid reducers, usually started as an eight-week trial.
5. Specialist assessment: tests and, for a small group, surgery or an endoscopic procedure.

Antacids: fastest relief

Antacids neutralise acid that is already in the stomach. They work within minutes but only last a short time, and they do not stop reflux from happening.

• Common ingredients: calcium carbonate (for example Rennie, Tums), magnesium hydroxide and aluminium hydroxide (for example Maalox).
• Best for: occasional, mild heartburn, such as after a rich meal. Often taken after meals and at bedtime.
• Side effects: magnesium can loosen the bowels; calcium and aluminium can cause constipation.
• Cautions: antacids can reduce absorption of other medicines, including iron, some antibiotics and thyroid tablets, so leave a gap of about two hours. Products high in sodium (such as sodium bicarbonate) are unsuitable for people on a low-salt diet and in pregnancy. Ask a pharmacist if you have kidney problems.

Alginates: a protective raft

Alginates (for example Gaviscon) are made from seaweed. In the stomach they form a thick gel "raft" that floats on top of the stomach contents and acts as a physical barrier against reflux. Most also contain an antacid. Gaviscon Advance contains sodium alginate and potassium bicarbonate.

• Best for: symptoms after meals and at bedtime, and regurgitation.
• Pregnancy: because very little is absorbed into the body, alginates and antacids are usually the first choice in pregnancy. See reflux in pregnancy.
• Side effects: uncommon; some people notice bloating. Check the sodium content if you are on a low-salt diet.

H2 blockers

H2 receptor antagonists reduce how much acid the stomach makes by blocking histamine, one of the signals that switches on acid production. Famotidine (for example Pepcid) is the most widely used; cimetidine is older and interacts with more medicines. Ranitidine (Zantac) was withdrawn worldwide in 2020 after an impurity called NDMA was found, and should not be used.

• Onset and duration: they start working in about an hour and last several hours, so they can be taken before a meal you expect to cause trouble, or at bedtime.
• Limitations: the effect tends to fade when they are taken every day for weeks (tolerance), so they are less suited to continuous use than PPIs.
• Side effects: usually mild and uncommon, such as headache, dizziness or diarrhoea.

Proton pump inhibitors (PPIs)

PPIs are the most effective acid-reducing medicines and the standard treatment for frequent GERD and for inflammation of the oesophagus (oesophagitis). They block the "proton pump", the final step of acid production in the stomach lining. Examples include omeprazole, esomeprazole, lansoprazole, pantoprazole and rabeprazole. Low doses of some are sold without a prescription in many countries.

How to take them

Take your PPI 30 to 60 minutes before a meal, usually breakfast. PPIs only block pumps that are active, and pumps switch on when you eat. Taking a PPI at bedtime or without a meal afterwards makes it less effective, and this is one of the most common reasons people think their PPI is "not working". If you are prescribed a second daily dose, take it 30 to 60 minutes before your evening meal.

How long for

Guidelines recommend an eight-week trial of a once-daily PPI for typical heartburn and regurgitation without warning signs. If symptoms settle, your doctor will usually try to reduce the dose or stop it, or switch to taking it only when needed. People with severe oesophagitis or Barrett's oesophagus usually need to stay on a PPI long term. If symptoms do not improve, the next step is usually tests rather than ever-higher doses. See diagnosis and tests.

Stopping a PPI

Some people get a temporary rebound of heartburn for a few weeks after stopping a PPI, because the stomach briefly makes extra acid. This can feel like the original problem returning. Reducing the dose gradually, and using antacids or alginates for breakthrough symptoms, can help. Agree a plan with your doctor.

Long-term safety

PPIs are among the most widely used medicines in the world and are generally safe. Large observational studies have linked long-term use with problems such as low magnesium, low vitamin B12, bone fractures, gut infections (including C. difficile) and kidney disease. Most of these links are small and may not be caused by the PPI itself. Expert advice from the American Gastroenterological Association is:

• if you have a clear reason to take a PPI, such as severe oesophagitis or Barrett's oesophagus, the benefits outweigh these possible risks
• if you take one for symptoms only, use the lowest dose that works, and review every year or so whether you still need it

Side effects

Usually mild: headache, diarrhoea, nausea, stomach pain or constipation. Contact a doctor if you develop a rash, joint pain, severe or persistent diarrhoea, or other new symptoms.

Newer and add-on medicines

• Potassium-competitive acid blockers (P-CABs), such as vonoprazan, block acid in a different way from PPIs and are approved for reflux in some countries, including the US and Japan.
• Baclofen reduces LOS relaxations and is sometimes tried by specialists when reflux is proven and continues despite optimal PPI treatment. It can cause drowsiness and dizziness.
• Prokinetics (such as metoclopramide and domperidone) speed up stomach emptying. Guidelines advise against them for GERD unless there is also slow stomach emptying, and both carry safety restrictions.

At a glance

When medicine is not enough

A minority of people still have troublesome symptoms on medicine, mostly regurgitation, or do not want to take medicine for life. Before any procedure, specialists confirm reflux with tests (reflux monitoring, and manometry to check how the oesophagus moves). Options include:

• Laparoscopic fundoplication: keyhole surgery in which the top of the stomach is wrapped around the lower oesophagus to strengthen the barrier, often with repair of a hiatus hernia. Results are good for carefully selected patients. Some people have difficulty swallowing, bloating or trouble belching afterwards.
• Magnetic sphincter augmentation (LINX): a small ring of magnetic beads placed around the lower oesophagus. It stays closed at rest and opens when you swallow. Recommended as an alternative to fundoplication for regurgitation that does not respond to medicine.
• Transoral incisionless fundoplication (TIF): an endoscopic procedure through the mouth, considered for some people without severe oesophagitis or a large hiatus hernia.
• Gastric bypass: for people with obesity who are considering surgery, a Roux-en-Y gastric bypass treats reflux and helps with weight loss.

These decisions should be made with a gastroenterologist and an experienced upper GI surgeon.

Medicines that can make reflux worse

If symptoms started or got worse after a new medicine, tell your doctor or pharmacist. Never stop a prescribed medicine on your own; the condition it treats may matter more, and alternatives often exist.

• Anti-inflammatory painkillers (NSAIDs) such as ibuprofen, naproxen, diclofenac and aspirin can irritate the stomach and oesophagus. Paracetamol (acetaminophen) is usually gentler.
• Calcium channel blockers (for example amlodipine, nifedipine) and nitrates, used for blood pressure and angina, can relax the LOS.
• Some antidepressants, particularly tricyclics such as amitriptyline, and other anticholinergic medicines.
• Bisphosphonates for osteoporosis (such as alendronic acid) can irritate the oesophagus. Take them exactly as instructed: with a full glass of water, staying upright for at least 30 minutes.
• Tablets that can stick and irritate, such as potassium, iron and some antibiotics like doxycycline. Take them with plenty of water and not just before lying down.
• Theophylline for asthma or COPD, opioid painkillers, and sedatives.
• Hormones containing progesterone may contribute in some people.

Key tips

• Take PPIs 30 to 60 minutes before breakfast.
• Give a PPI trial the full eight weeks, together with lifestyle changes.
• Do not stop a long-term PPI suddenly; reduce it with your doctor's help.
• Leave about two hours between antacids and other medicines.
• Review long-term reflux medicine with your doctor at least once a year.