Rybelsus side effects: what is common and what is serious

The most common side effects of Rybelsus (oral semaglutide) affect the stomach and gut: nausea, diarrhoea, vomiting, stomach pain, constipation and a smaller appetite. In the US placebo-controlled trials, nausea affected 11% of people on 7 mg and 20% on 14 mg, compared with 6% on placebo, and most nausea, vomiting and diarrhoea happened while the dose was being stepped up¹. Serious side effects are much less common but need prompt medical help: severe stomach pain that could be pancreatitis, gallbladder problems, dehydration that harms the kidneys, severe allergic reactions and sudden changes in vision.

This guide is based on the official prescribing information from the US (FDA label), the EU (EMA SmPC) and the UK (MHRA-approved SmPC). The trial figures were collected with the 7 mg and 14 mg tablets. The newer 4 mg and 9 mg tablets are equivalent doses (in the US they are sold as Ozempic tablets), and Novo Nordisk says they have the same safety profile as the original tablets, based on a bioequivalence study¹¹¹.

What are the most common side effects of Rybelsus?

The US label lists six side effects that affected 5% or more of people in its placebo-controlled trials. All of them involve the digestive system¹.

Taken together, 41% of people on 14 mg, 32% on 7 mg and 21% on placebo reported at least one gastrointestinal side effect. Severe gastrointestinal reactions were much less common: 2.0%, 0.6% and 0.3%. Stomach side effects led 8% of people on 14 mg to stop treatment, compared with 4% on 7 mg and 1% on placebo¹.

The US label also notes a small rise in heart rate (1 to 3 beats per minute) and higher blood levels of the pancreatic enzymes amylase and lipase. Since approval there have been reports of ileus (the gut temporarily stopping moving food along), intestinal obstruction, severe constipation, hair loss, dizziness, headache and changes in taste¹. The EMA's safety committee looked at reports of suicidal thoughts with GLP-1 medicines and concluded in April 2024 that the evidence does not support a causal link⁸.

How common are side effects in the EU and UK labels?

European and UK labels group side effects by how often they happen. For Rybelsus the main groups are:

• Very common (more than 1 in 10 people): nausea, diarrhoea, and hypoglycaemia (low blood sugar) when Rybelsus is used with insulin or a sulfonylurea²³.
• Common (between 1 in 100 and 1 in 10): vomiting, stomach pain, bloating, constipation, indigestion, gastritis (inflammation of the stomach lining), acid reflux, wind, reduced appetite, dizziness, headache, altered skin sensation, complications of diabetic eye disease, tiredness, raised lipase and amylase, and hypoglycaemia with other oral diabetes medicines²³.
• Uncommon (between 1 in 1,000 and 1 in 100): allergic reactions, taste changes, a faster heart rate, burping, slower stomach emptying, gallstones and weight loss².
• Rare (between 1 in 10,000 and 1 in 1,000): anaphylaxis (a severe, whole-body allergic reaction) and acute pancreatitis².
• Very rare (fewer than 1 in 10,000): non-arteritic anterior ischaemic optic neuropathy (NAION), a sudden loss of vision in one eye²⁶.
• Frequency not known: intestinal obstruction².

The EU label also gives percentages for the standard doses: nausea 15%, diarrhoea 10% and vomiting 7%, with about 4% of people stopping because of gastrointestinal effects. At the higher 25 mg and 50 mg doses, which are authorised only in the EU, nausea affected 27%².

How long do Rybelsus side effects last?

The labels do not give a fixed number of days or weeks. What they do show is when stomach side effects are most likely. In the US trials, most nausea, vomiting and diarrhoea happened during dose escalation, the weeks when the dose is being stepped up¹. Novo Nordisk's patient information says these effects are most common when you start and after a dose increase⁵.

That is the reason treatment starts low. The first dose (3 mg, or 1.5 mg with the newer tablets) is "not effective for glycemic control", in the words of the US label; it is there to reduce stomach side effects¹. Each step lasts at least a month, and the labels set minimum times rather than fixed ones, so a prescriber can keep you on a lower dose for longer¹³. Do not change your dose yourself; talk to your prescriber. The Rybelsus dosage guide explains the steps.

Semaglutide is also long-acting. Its half-life is about one week, it takes 4 to 5 weeks of daily dosing to reach steady levels, and it stays in the blood for about five weeks after the last dose¹.

For a longer view, the SOUL trial followed people for about four years. Over that time, 15.5% of people on oral semaglutide and 11.6% on placebo stopped the study drug because of an adverse event of any kind¹⁹.

What helps with Rybelsus nausea?

Novo Nordisk's US patient website suggests these steps for nausea⁵:

• Eat bland, low-fat foods such as crackers, toast and rice.
• Choose foods that contain water, such as soups and jelly.
• Avoid fried, greasy or sweet foods.
• Eat slowly, and do not lie down straight after eating.
• Drink cold water and get some fresh air.

The NHS advises avoiding alcohol, because it can make nausea and vomiting worse⁴. These are practical suggestions from patient information rather than instructions in the prescribing information.

If you are vomiting or have diarrhoea, keep drinking fluids. Vomiting and diarrhoea can lead to dehydration and kidney problems, so contact a healthcare professional if symptoms are severe or do not go away¹⁵. If nausea keeps coming back, ask your prescriber whether staying longer on your current dose is an option. For the daily routine itself, see how to take Rybelsus.

Serious side effects: when to get medical help

These are less common, but the labels ask you to act quickly if they happen.

Pancreatitis

Acute pancreatitis is inflammation of the pancreas. The warning sign is severe stomach pain that does not go away and may spread to your back. The US label says to stop the medicine and get medical help if pancreatitis is suspected¹. In the pooled diabetes trials it was reported as a serious event at 0.1 events per 100 patient-years¹, and the EU label classes it as rare². The UK label says semaglutide should not be restarted if pancreatitis is confirmed³.

Gallbladder problems

Gallstones and inflammation of the gallbladder (cholecystitis) have been reported. In placebo-controlled trials, gallstones affected 1% of people on 7 mg. In SOUL, gallstones were reported in 1.1% of people on oral semaglutide vs 0.9% on placebo, and cholecystitis in 1.1% vs 0.7%¹. The US label says gallbladder tests are indicated if these problems are suspected¹, so tell a doctor about stomach pain that is new, severe or does not settle.

Dehydration and kidney injury

Acute kidney injury, sometimes needing dialysis, has been reported, mostly in people who became dehydrated from nausea, vomiting or diarrhoea¹. Contact a healthcare professional if vomiting or diarrhoea is severe or does not stop¹⁵.

Serious allergic reactions

Serious allergic reactions have been reported, including anaphylaxis and angioedema (swelling under the skin, for example of the face, lips or throat)¹. The EU label classes anaphylaxis as rare². A severe allergic reaction is a medical emergency.

Vision changes

Diabetic retinopathy is damage to the blood vessels at the back of the eye caused by diabetes. A fast improvement in blood sugar can temporarily make it worse, and people with a history of it should be monitored¹³. In pooled tablet trials, retinopathy-related side effects affected 4.2% of people on semaglutide vs 3.8% on comparator medicines. In the SUSTAIN-6 trial of injected semaglutide, retinopathy complications were 3.0% vs 1.8%, and the increase was larger in people who already had retinopathy (8.2% vs 5.2%) than in those who did not (0.7% vs 0.4%)¹.

Separately, the EMA's safety committee concluded in June 2025 that NAION is a very rare side effect of semaglutide medicines, and the MHRA issued advice in February 2026. Anyone with sudden loss of vision should get urgent medical help⁶⁷⁴.

Low blood sugar with other diabetes medicines

Used without other medicines that cause hypoglycaemia, semaglutide has a low risk of it. The risk rises, including the risk of severe hypoglycaemia, when it is taken with insulin or a sulfonylurea, and the prescriber may lower the dose of those medicines¹³. The Rybelsus safety guide covers this and other warnings in more detail.

How to report a side effect

Tell your prescriber or pharmacist about any side effect that worries you. You can also report suspected side effects yourself:

• UK: the MHRA's Yellow Card scheme¹⁰.
• US: the FDA's MedWatch programme¹.
• Elsewhere: your national medicines regulator runs a similar scheme, and your pharmacist can tell you how to use it.

When you report, include the product name and strength (for example Rybelsus 4 mg or Ozempic tablets 9 mg) and, if you have it, the batch number from the pack. If you think the product itself may not be genuine, see buying Rybelsus safely.