Why these reactions are easy to miss
Table 1 of the US Ozempic® label only includes reactions reported by at least 5% of treated adults. Everything less frequent but still associated with the medicine appears in running text underneath, using medical terms: dyspepsia for indigestion, gastroesophageal reflux disease (GERD) for acid coming back up, eructation for burping and gastritis for inflammation of the stomach lining. The numbers come from the same two placebo-controlled trials in adults with type 2 diabetes as the main table [1].
Europe takes a different route and places dyspepsia, gastritis, reflux disease, eructation, flatulence and abdominal distension together in its common class, between 1 in 100 and 1 in 10 people [2].
The upper-stomach rates in two documents
The US figures compare Ozempic® with placebo; the Canadian figures come from a larger seven-trial pool with a comparator group that mixes placebo and other diabetes medicines [1][3].
| Reaction | US: placebo / 0.5 mg / 1 mg [1] | Canada: comparator / 0.5 mg / 1 mg [3] |
|---|---|---|
| Dyspepsia (indigestion) | 1.9% / 3.5% / 2.7% | 2.1% / 4.1% / 5.2% |
| Gastroesophageal reflux disease | 0% / 1.9% / 1.5% | 1.0% / 1.6% / 2.7% |
| Eructation (burping) | 0% / 2.7% / 1.1% | 0.2% / 1.3% / 1.8% |
| Gastritis | 0.8% / 0.8% / 0.4% | 0.5% / 1.6% / 1.2% |
| Abdominal distension (bloating) | Not listed | 0.8% / 2.3% / 2.9% |
What the pattern suggests
In the US table, reflux and burping were not reported at all on placebo, and indigestion was more frequent on both doses than on placebo. Gastritis on Ozempic® was no higher than on placebo. In each upper-stomach row the 0.5 mg group reported slightly more than the 1 mg group, which the label does not explain [1].
The Canadian pool, which is about six times larger, runs the other way for indigestion, reflux and burping: the 1 mg group reported a little more than the 0.5 mg group [3]. With small numbers like these, the safest reading is that both doses sit above the comparison group and the order between doses is not settled.
Timing is less clear than for nausea. The US label ties nausea, vomiting and diarrhea to dose escalation but says nothing similar about heartburn, and the European note on SUSTAIN 9 suggests reflux disease can persist rather than fade [1][2].
What a large meta-analysis found
A 2025 systematic review pooled 55 placebo-controlled randomised trials of GLP-1 medicines with 106,395 participants, including people with type 2 diabetes, obesity and fatty liver disease. GLP-1 medicines probably increased reflux disease (risk ratio 2.19, about 4 more cases per 1,000 people) but probably had little or no effect on gastritis, oesophagitis or stomach ulcers [4].
The rise in reflux looked larger in trials of people with overweight or obesity, of medicines that cause more weight loss and of higher doses, although those subgroup differences were not statistically significant. The review covered the whole class, not Ozempic® alone [4].
Why it may happen
What the label supports: semaglutide causes a minor delay in stomach emptying in the early period after a meal, and Europe lists delayed gastric emptying as an uncommon reaction [1][2].
What is plausible but unproven: food staying longer in the stomach could make it easier for contents to press back up into the oesophagus. None of the Ozempic® documents states that link, and the meta-analysis measured how often reflux occurred, not why [4].
General background: MedlinePlus explains that reflux happens when the ring of muscle at the lower end of the oesophagus does not close fully, and that lying down soon after a meal, obesity, pregnancy, smoking and a hiatal hernia all make it more likely [6].
Other causes of heartburn
- Medicines including some blood pressure and heart medicines (beta-blockers, calcium channel blockers), asthma inhalers that widen the airways, theophylline, tricyclic antidepressants, sedatives and progestin [5][6].
- Trigger foods and drinks: alcohol, caffeine, fizzy drinks, chocolate, citrus, mint, tomatoes and spicy or fatty foods [5].
- A hiatal hernia, pregnancy and smoking [5][6].
- Pain that feels like heartburn but comes from the heart, the gallbladder or the pancreas; the Ozempic® label has warnings for the last two [1][5].
What may help
The Ozempic® documents give no specific advice for heartburn. The steps below come from MedlinePlus and NIDDK’s general guidance on reflux [5][7][8].
- Eat smaller meals, and avoid bending over or exercising straight after eating [5].
- Leave a gap of a few hours between your last meal and lying down or going to bed [5][8].
- Raise the head end of the bed; MedlinePlus suggests blocks or a wedge under the mattress, because loose pillows tend to slip in the night [5].
- Notice which foods seem to trigger symptoms and discuss cutting back on them with your doctor [8].
- Avoid tight belts or waistbands, and stop smoking if you smoke [5][7].
- Antacids and acid-reducing medicines are sold without a prescription, but NIDDK advises against daily antacid use or use for severe symptoms without talking to a doctor [7]. The Ozempic® label also asks you to tell your provider about every medicine you take, including over-the-counter ones [1].
Details worth noting
It helps to note when the burning starts relative to meals and bedtime, what you ate, whether lying down makes it worse, whether you also burp, feel bloated or bring food back up, and whether it began after starting Ozempic® or after a dose change. If you use antacids, write down how often.
Ozempic® is a registered trademark of Novo Nordisk A/S. PepLabo is not affiliated with or endorsed by Novo Nordisk.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Burning in the chest with squeezing, crushing or pressure | Emergency services (911); it may be a heart attack | Emergency | MedlinePlus [5] |
| Vomiting blood or material like coffee grounds, or black or maroon stools | Urgent medical care | Emergency | MedlinePlus [5] |
| Severe stomach pain that does not ease, sometimes into the back, with or without vomiting | Stop Ozempic® and call your healthcare provider straight away | Emergency | Medication Guide [1] |
| Upper stomach pain with fever, yellow skin or eyes, or clay-coloured stools | Your healthcare provider, straight away | Today | Medication Guide [1] |
| Trouble or pain swallowing, food feeling stuck, or weight loss you did not intend | Your healthcare provider | Today | MedlinePlus [5][6] |
| Heartburn that is frequent or does not settle after a few weeks of self-care | Your healthcare provider or prescriber | At your next appointment | MedlinePlus [5] |
