Ozempic Side Effects: What the Trials Actually Show, From Common Nausea to Rare Risks

How common are the common side effects?

Ozempic injection is approved for type 2 diabetes, and its label's side-effect table comes from placebo-controlled trials in adults with type 2 diabetes [1]. At 0.5 mg and 1 mg weekly, the rates were:

• Nausea: 15.8% and 20.3% vs 6.1% on placebo.
• Vomiting: 5% and 9.2% vs 2.3%.
• Diarrhea: 8.5% and 8.8% vs 1.9%.
• Abdominal pain: 7.3% and 5.7% vs 4.6%.
• Constipation: 5% and 3.1% vs 1.5% [1].

Any GI reaction occurred in 32.7% on 0.5 mg and 36.4% on 1 mg vs 15.3% on placebo; 3.1% and 3.8% stopped for GI reasons vs 0.4% [1]. In the 2 mg vs 1 mg trial of 959 patients over 40 weeks, GI reactions were 34% on 2 mg vs 30.8% on 1 mg, with no new safety signals [1]. The label says the majority of nausea, vomiting and diarrhea occurred during dose escalation [1]. The label's schedule starts at 0.25 mg for 4 weeks and increases only after at least 4 weeks at the current dose [1].

What serious risks does the label warn about?

The Ozempic label lists acute pancreatitis, acute gallbladder disease, severe GI reactions, acute kidney injury due to volume depletion, hypoglycemia with insulin secretagogues or insulin, serious hypersensitivity, diabetic retinopathy complications, and pulmonary aspiration during general anesthesia or deep sedation [1]. Some of these have trial rates; others are postmarketing reports where frequency cannot be estimated from voluntary reports [1].

For pancreatitis, the label says acute pancreatitis, including fatal and nonfatal hemorrhagic or necrotizing pancreatitis, has been observed with GLP-1 receptor agonists including Ozempic, and it says to discontinue if pancreatitis is suspected [1]. The label describes persistent or severe abdominal pain, sometimes radiating to the back, with or without nausea or vomiting [1].

Severe GI reactions occurred in 0.4% on 0.5 mg and 0.8% on 1 mg vs 0% on placebo [1]. Postmarketing reports include ileus, intestinal obstruction, and severe constipation with fecal impaction [1]. Acute kidney injury reports mostly occurred after GI reactions causing dehydration, and the label says to monitor renal function in patients with reactions that could lead to volume depletion [1].

Diabetic retinopathy complications occurred in 3.0% on semaglutide vs 1.8% on placebo in a 2-year trial; in people with prior retinopathy, the rates were 8.2% vs 5.2% [1]. The label says patients with a history of diabetic retinopathy should be monitored [1].

Does Ozempic cause low blood sugar?

The label's main hypoglycemia warning is for use with insulin or an insulin secretagogue such as a sulfonylurea [1]. In the add-on to basal insulin trial, documented symptomatic hypoglycemia at 70 mg/dL or lower occurred in 15.2% on placebo, 16.7% on 0.5 mg and 29.8% on 1 mg; severe hypoglycemia occurred in 0%, 0% and 1.5% [1]. In the monotherapy trial, severe hypoglycemia was 0% in all arms, and documented symptomatic hypoglycemia was 0% on placebo, 1.6% on 0.5 mg and 3.8% on 1 mg [1]. The label says reducing the dose of the sulfonylurea or insulin may be necessary when starting Ozempic [1].

Does Ozempic cause gastroparesis?

The Ozempic label says Ozempic is not recommended for people with severe gastroparesis and lists ileus and intestinal obstruction among postmarketing reports; it does not say Ozempic causes gastroparesis [1]. The label separately states that Ozempic delays gastric emptying, and it groups severe gastrointestinal reactions under its warnings [1].

What about the NAION eye risk?

The current US Ozempic label does not mention NAION [1]. In Europe, EMA's safety committee concluded in June 2025 that NAION is a very rare side effect of semaglutide, up to 1 in 10,000 people, with about one extra case per 10,000 person-years and roughly a two-fold relative risk in large studies of adults with type 2 diabetes [2].

A 2024 retrospective matched cohort at one academic center found more NAION events among patients prescribed semaglutide; in the type 2 diabetes group, 17 events occurred on semaglutide vs 6 in the comparator group [3]. A 2026 claims study of GLP-1 receptor agonists as a class matched 482,912 pairs of GLP-1 receptor agonist and SGLT2 inhibitor initiators with type 2 diabetes and found a higher risk of presumed NAION with the GLP-1 drugs (HR 1.85; 95% CI, 1.51 to 2.27; rate difference, 0.29 per 1,000 person-years over a median 6.7 months on treatment) [4]. In its statement, EMA says patients who experience sudden vision loss or rapidly worsening eyesight should contact their doctor without delay, and that semaglutide should be stopped if NAION is confirmed [2].

Who should not take Ozempic?

The label contraindicates Ozempic in people with a personal or family history of MTC or MEN 2, and in people with a prior serious hypersensitivity reaction to semaglutide or an excipient [1]. The boxed warning is based on rodent thyroid C-cell tumors; whether semaglutide causes these tumors in humans is unknown [1]. The label lists thyroid tumor symptoms to watch for: a mass in the neck, trouble swallowing, shortness of breath and persistent hoarseness [1].

The label says to discontinue Ozempic at least 2 months before a planned pregnancy because of the long washout period [1]. The Ozempic label says use during pregnancy only if the potential benefit justifies the potential risk to the fetus [1].