Mounjaro Heartburn: Everything You Need to Know

Heartburn is a common symptom that some people experience when taking Mounjaro. It happens because the treatment slows digestion, which can increase the chance of acid reflux. Here, we explain why it occurs, how long it lasts, and what you can do to manage it.

Three key takeaways

• Mounjaro can sometimes cause or worsen heartburn, especially at higher doses.
• Lifestyle changes and heartburn relief treatments can help control symptoms.
• Severe or ongoing heartburn should always be checked by a healthcare professional.

Does Mounjaro cause heartburn?

Yes - heartburn is a known side effect of Mounjaro, though not everyone will get it and it may be more noticeable at higher doses or when first starting treatment. Some people only notice mild discomfort, while others may need adjustments in dose or extra support from their prescriber.

Why does Mounjaro cause heartburn?

Mounjaro slows down how quickly your stomach empties after eating. When food stays in the stomach for longer, it can create extra pressure and push acid back into the oesophagus, which causes the burning feeling of heartburn.

Because Mounjaro also reduces appetite, many people eat smaller meals. This change in digestion patterns can sometimes make reflux more noticeable, especially in the first few weeks of treatment.

How long does Mounjaro heartburn last?

Heartburn with Mounjaro is temporary for most people and settles after the first few weeks as the body adapts.

Side effects like heartburn often improve once your digestion adjusts to the slower emptying caused by the medication. Some people may only notice mild discomfort after meals, while others might need dose adjustments or additional treatment to manage symptoms. Persistent heartburn should never be ignored, as it can affect long-term health. If symptoms continue or become severe, you should consult your GP or pharmacist for advice.

How to stop or reduce heartburn on Mounjaro

Lifestyle changes to reduce heartburn

• Eat smaller meals

Large meals put extra pressure on the stomach, pushing acid back into the oesophagus. Smaller, more frequent meals are easier to digest and lower reflux risk.

• Avoid lying down after eating

Staying upright for at least 2–3 hours after meals gives your stomach time to empty. Lying flat too soon increases the likelihood of acid reflux.

• Cut back on spicy, fatty, or acidic foods

Spicy dishes, fried foods, citrus, and tomatoes are common heartburn triggers. These can irritate the oesophagus or relax the valve that normally prevents acid reflux.

• Limit alcohol and fizzy drinks

Alcohol and carbonated drinks both increase pressure in the stomach and can weaken the lower oesophageal sphincter (the muscle that keeps acid down).

• Sit with good posture while eating

Slouching or hunching compresses your stomach, while sitting upright helps food move through your digestive system and reduces your risk of heartburn.

• Maintain a healthy weight

Excess weight, especially around the abdomen, increases pressure on the stomach, making acid reflux and heartburn more likely.

• Quit smoking

Nicotine relaxes the lower oesophageal sphincter, making it easier for acid to escape from the stomach into the oesophagus.

• Raise the head of your bed if symptoms occur at night

Sleeping with your upper body elevated helps prevent acid from flowing back into the oesophagus while you rest.

Medications for relief

Over-the-counter antacids, which neutralise stomach acid, can provide short-term relief. If symptoms are more frequent, a GP may recommend medicines such as proton pump inhibitors (PPIs) or H2 blockers.

Your GP should always supervise long-term use of medicines such as PPIs, as taking them for extended periods without review may lead to side effects or nutrient deficiencies. Always speak to a pharmacist or doctor before starting any new treatment alongside Mounjaro to ensure safety.

When to seek medical advice (Red Flags)

See your GP if heartburn is severe, persistent, or doesn’t improve with lifestyle changes.

Red flag symptoms are warning signs that heartburn may not simply be a side effect of Mounjaro. Because persistent reflux can sometimes mask more serious conditions, it’s important to act quickly if you notice:

• difficulty swallowing
• vomiting blood
• black or tarry stools
• unexplained weight loss outside of expected treatment

If you have any of these symptoms, seek urgent medical advice. Early review ensures that serious conditions are ruled out and that your treatment remains safe.

Frequently asked questions

Does Mounjaro cause heartburn at every dose?

No. Not everyone will experience heartburn. If it does occur, it may be more likely at higher doses. Your prescriber can adjust your treatment if symptoms become difficult to manage.

Does heartburn go away once your body adjusts?

Heartburn is often temporary in the first few weeks of treatment and settles as the body adapts. If it persists, speak to your GP. This pattern is similar to other common Mounjaro side effects, such as nausea or constipation, which usually improve over time.

Can you prevent Mounjaro heartburn before it starts?

Prevention is possible by eating smaller meals, avoiding trigger foods, and not lying down after eating. Staying upright and limiting alcohol or fizzy drinks can also reduce your risk. Keeping a food and symptom diary can help you spot which meals make your reflux worse and adjust your diet more effectively.

Why is heartburn worse after eating?

When the stomach is fuller, pressure increases and makes acid reflux more likely. Mounjaro slows digestion, so food remains in the stomach longer, which can make symptoms more noticeable after meals.

What should I do if I have severe heartburn on Mounjaro?

Contact your GP if symptoms are severe, persistent, or don’t improve with lifestyle changes. Seek urgent care if you also have red flag symptoms such as vomiting blood or unexplained weight loss.

Sources

• 5 lifestyle tips for a healthy tummy (2022) NHS [Accessed 29 September 2025]
• Indigestion (2023) NHS [Accessed 29 September 2025]
• Tirzepatide for managing overweight and obesity (2024) NICE [Accessed 29 September 2025]