Heartburn on Mounjaro or Wegovy: What's Going On and What to Do

Both Mounjaro and Wegovy work, in part, by slowing the rate at which the stomach empties — an effect linked to how GLP-1 receptor agonists influence digestion. When food sits in the stomach for longer than usual, pressure can build, and stomach acid is more likely to travel back up into the oesophagus. That's the sensation most people recognise as heartburn or acid reflux.

For Mounjaro specifically, the additional action on GIP receptors may also influence gastric motility, which is why gastrointestinal side effects — including indigestion and reflux — appear on the medicine's patient information. According to NHS guidance, reflux and indigestion are listed among the common side effects of medicines in this class.

When is heartburn most likely?

• After eating larger meals: even if your appetite has reduced, eating more than your stomach is comfortable with can worsen reflux.
• Around dose increases: the slowing of stomach emptying tends to be strongest at a new dose level and often eases over time.
• Late at night: lying down shortly after eating can make acid reflux more noticeable — many people find leaving a gap between eating and going to bed helps.
• With certain foods or drinks: fatty foods, fizzy drinks, coffee, and alcohol are commonly associated with worsening reflux regardless of the medicine.

Some general adjustments many people on GLP-1 medicines find helpful include eating smaller portions, slowing down at mealtimes, and staying upright for a while after eating. These are general observations rather than medical instructions — your prescriber or doctor is the right person to advise on managing persistent or severe symptoms.

If you're also noticing other digestive changes alongside heartburn, you might find it useful to read about constipation on Mounjaro or constipation on Wegovy, as slower digestion can affect the gut in more than one way. Fatigue sometimes accompanies these GI side effects too — see tiredness on Mounjaro for more on that.

One of the most useful things you can do when you're experiencing heartburn on your GLP-1 medicine is to keep a clear record — noting when it happens, how severe it felt, and what you ate or did beforehand. Over time, patterns often emerge that aren't obvious in the moment.

GLP Trackr's side-effect tracking lets you log heartburn and other digestive symptoms quickly after each occurrence, so nothing gets forgotten before your next appointment. Because the app also logs your doses and food intake, you can use the insights view to see whether flare-ups correspond with dose days, particular meals, or other factors — exactly the kind of joined-up picture your prescriber will find useful when reviewing how you're getting on.

The food logging feature (including an AI photo scan option) makes it easy to record what you ate around the time symptoms appeared, without needing to type everything out. Spotting a link between, say, a heavier evening meal and a rough night of reflux is much easier when the data is already there.

You can bring a summary of your logged symptoms directly to your next appointment using the app's doctor report — a clear, time-stamped record that takes the guesswork out of those conversations.

For a broader overview of digestive and other side effects associated with these medicines, the Mounjaro side effects guide covers the full picture.

Important: if your heartburn is severe, persistent, or accompanied by difficulty swallowing, chest pain, or vomiting, contact your healthcare professional promptly. GLP Trackr helps you record what you experience so you can discuss it with your prescriber — it is not a substitute for their advice, and any decisions about managing or changing your treatment should be made with them.

Any side effects worth reporting to your prescriber may also be reportable through your national pharmacovigilance scheme (such as the UK's Yellow Card scheme) — your prescriber or pharmacist can advise on how this works in your country.

Start logging your symptoms and see your own patterns emerge — GLP Trackr is free to try for 7 days on the App Store and Google Play.