Ozempic Side Effects Severity Distribution by Patient Phenotype

Where the rates come from

The figures on this page are from the pooled placebo-controlled trials described in the Ozempic prescribing information: two trials in adults with type 2 diabetes, one as monotherapy and one in combination with basal insulin, covering 521 people treated with Ozempic for a mean of 32.9 weeks [1]. At baseline the average HbA1c was 8.2%, diabetes duration averaged 8.8 years, 8.9% of participants had reported retinopathy and 6.9% had an eGFR between 30 and 60 [1].

That population matters for reading the numbers. Ozempic is approved to improve glycemic control in adults with type 2 diabetes, to reduce major cardiovascular events in adults with type 2 diabetes and established cardiovascular disease, and to reduce the risk of sustained eGFR decline, end-stage kidney disease and cardiovascular death in adults with type 2 diabetes and chronic kidney disease; it has no weight-loss indication [1].

The common reactions from Table 1 of the label, by arm [1]:

Severe GI reactions by dose, and timing during escalation

Severe gastrointestinal reactions were reported in 0.4% of people on 0.5 mg and 0.8% on 1 mg, against 0% on placebo [1]. Any gastrointestinal reaction occurred in 15.3% on placebo, 32.7% on 0.5 mg and 36.4% on 1 mg, and treatment was discontinued for gastrointestinal reasons in 0.4%, 3.1% and 3.8% respectively [1].

The label states that the majority of reports of nausea, vomiting and diarrhea occurred during dose escalation [1]. Its schedule is 0.25 mg weekly for 4 weeks, then 0.5 mg, with further steps to 1 mg and then 2 mg after at least 4 weeks on the current dose if more glycemic control is needed [1].

The 2 mg dose was compared with 1 mg in a separate trial. A 40-week trial of 959 patients on 1 mg or 2 mg as add-on to metformin, with or without a sulfonylurea, reported gastrointestinal reactions in 34% on 2 mg versus 30.8% on 1 mg, with no new safety signals [1]. Those are two arms of one trial; the 0.5 mg and 1 mg percentages above come from a different pooled dataset, so the two comparisons are not interchangeable [1].

The subgroups where the label reports different rates

People taking insulin or a sulfonylurea

In the trial that added Ozempic to basal insulin with or without metformin, documented symptomatic hypoglycemia at or below 70 mg/dL occurred in 15.2% on placebo, 16.7% on 0.5 mg and 29.8% on 1 mg, with severe hypoglycemia (requiring another person's assistance) in 0%, 0% and 1.5% [1]. In the monotherapy trial the same measure was 0%, 1.6% and 3.8%, with no severe events in any arm [1]. The label notes hypoglycemia was more frequent when Ozempic was used with a sulfonylurea, and that reducing the sulfonylurea or insulin dose may be necessary when starting [1].

People with a history of diabetic retinopathy

In a 2-year cardiovascular outcomes trial in type 2 diabetes with high cardiovascular risk, diabetic retinopathy complications occurred in 3.0% on Ozempic versus 1.8% on placebo [1]. The excess was concentrated in people who already had retinopathy at baseline: 8.2% versus 5.2% in that group, compared with 0.7% versus 0.4% in those without a known history [1]. The label notes that rapid improvement in glucose control has been associated with temporary worsening of diabetic retinopathy, and says patients with a history of retinopathy should be monitored for progression [1].

People with severe gastroparesis

The label states that Ozempic is not recommended in patients with severe gastroparesis, and that use has been associated with gastrointestinal adverse reactions, sometimes severe [1]. Ileus, intestinal obstruction and severe constipation including fecal impaction appear among postmarketing reports, for which frequency cannot be estimated from voluntary reporting [1]. The label does not state that semaglutide causes gastroparesis [1].

People with reduced kidney function

No dose adjustment is recommended for renal impairment [1]. The label describes postmarketing reports of acute kidney injury, in some cases requiring hemodialysis; most occurred in people whose gastrointestinal reactions, such as nausea, vomiting or diarrhea, led to dehydration [1]. The label says to monitor renal function in people reporting reactions that could lead to volume depletion, especially during initiation and escalation [1].

Other serious reactions the label lists

The boxed warning covers thyroid C-cell tumors: in rodents semaglutide caused dose- and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures, and whether it causes them in humans, including medullary thyroid carcinoma, is unknown [1]. Ozempic is contraindicated with a personal or family history of MTC or MEN 2, and routine calcitonin monitoring or thyroid ultrasound is of uncertain value [1].

Acute pancreatitis, including fatal and non-fatal hemorrhagic or necrotizing pancreatitis, has been observed with GLP-1 receptor agonists including Ozempic; the label says to watch for persistent or severe abdominal pain, sometimes radiating to the back, with or without nausea or vomiting, and to discontinue if pancreatitis is suspected [1]. Acute gallbladder disease is listed, with gallbladder studies indicated if cholelithiasis or cholecystitis is suspected [1]. Serious hypersensitivity reactions including anaphylaxis and angioedema have been reported [1]. Pulmonary aspiration during general anesthesia or deep sedation has been reported with GLP-1 receptor agonists [1]. The Ozempic label warns that sharing a pen, even after changing the needle, risks transmitting blood-borne pathogens [1].

Postmarketing reports in the label also include rash, urticaria, cholecystitis and cholecystectomy, dysesthesia, headache, and alopecia, none with an estimable frequency [1]. The current Ozempic label carries no suicidal behavior or ideation warning [1].

One eye condition is not in the US label: in June 2025 the European Medicines Agency's safety committee concluded that NAION (non-arteritic anterior ischemic optic neuropathy) is a very rare side effect of semaglutide, up to 1 in 10,000 people, corresponding to about one extra case per 10,000 person-years and roughly a two-fold relative risk in adults with type 2 diabetes, and advised stopping semaglutide if NAION is confirmed [2].

What these numbers cannot tell you

These are group rates from trials in type 2 diabetes. The label cautions that adverse reaction rates from one drug's clinical trials cannot be directly compared with rates from another drug's trials and may not reflect the rates observed in practice [1].