Ozempic side effects

Most common Ozempic side effects

In the label's placebo-controlled trials in adults with type 2 diabetes, which tested the 0.5 mg and 1 mg doses, the side effects reported in 5% or more of people were nausea, vomiting, diarrhea, abdominal pain and constipation.¹

Most of the nausea, vomiting and diarrhea occurred during the weeks when the dose was being stepped up.¹ Stomach and gut effects led 3.1% (0.5 mg) and 3.8% (1 mg) of people to stop treatment, against 0.4% on placebo.¹ In a separate trial comparing the 2 mg and 1 mg doses, they occurred in 34% and 30.8% of people.¹

Less common side effects

• Indigestion (dyspepsia): 3.5% on 0.5 mg and 2.7% on 1 mg, against 1.9% on placebo.¹
• Burping (eructation): 2.7% and 1.1%, against 0%.¹
• Acid reflux (GERD): 1.9% and 1.5%, against 0%. Gas (flatulence) and gastritis are also listed.¹
• Fatigue, taste changes (dysgeusia) and dizziness: each in more than 0.4% of people.¹
• Injection site reactions, such as discomfort or redness: 0.2%.¹
• Heart rate: an average rise of 2 to 3 beats per minute, against a fall of 0.3 on placebo.¹
• Pancreatic enzymes: average rises of 13% in amylase and 22% in lipase.¹

Low blood sugar

Low blood sugar was uncommon when Ozempic was used alone: documented symptomatic hypoglycemia occurred in 1.6% on 0.5 mg and 3.8% on 1 mg, against 0% on placebo.¹ Added to basal insulin, the rates were 16.7% and 29.8%, against 15.2% on placebo plus insulin; with a sulfonylurea they were 17.3% and 24.4%.¹ Severe hypoglycemia with a sulfonylurea occurred in 0.8% and 1.2%.¹ The label says the insulin or sulfonylurea dose may need to come down.¹

Reported after approval

These reports come from use of semaglutide, Ozempic's active ingredient, after approval. They were reported voluntarily, so how often they happen, and whether the drug caused them, cannot always be established:¹

• Pancreatitis, including necrotizing pancreatitis, sometimes fatal.¹
• Ileus, intestinal blockage and severe constipation, including fecal impaction.¹
• Rash and hives (urticaria).¹
• Gallbladder inflammation and gallbladder removal.¹
• Headache and abnormal skin sensations (dysesthesia).¹
• Acute kidney injury.¹
• Hair loss (alopecia).¹

Serious warnings on the label

Thyroid C-cell tumors (boxed warning)

Semaglutide caused thyroid C-cell tumors in mice and rats.¹ It is unknown whether Ozempic causes these tumors, including medullary thyroid carcinoma (MTC), in humans.¹ The label asks patients to report a lump or swelling in the neck, hoarseness, trouble swallowing or shortness of breath. It calls routine calcitonin tests or thyroid ultrasound of uncertain value for early detection.¹

Pancreatitis

Acute pancreatitis, including fatal and non-fatal hemorrhagic or necrotizing forms, has occurred with GLP-1 receptor agonists including Ozempic.¹ In the blood sugar trials it was confirmed in 7 people on Ozempic (0.3 cases per 100 patient-years) and 3 on comparison drugs (0.2).¹ The warning sign is persistent or severe stomach pain, sometimes spreading to the back, and the label says to stop Ozempic if pancreatitis is suspected.¹

Diabetic eye disease and NAION

In the 2-year SUSTAIN 6 trial, diabetic retinopathy complications occurred in 3.0% on Ozempic and 1.8% on placebo.¹ The gap was wider in people who already had retinopathy (8.2% against 5.2%) than in those who did not (0.7% against 0.4%), and the label says people with a history of retinopathy should be monitored.¹ The published trial reported a hazard ratio of 1.76 for these complications.²

Separately, in June 2025 the European Medicines Agency's safety committee concluded that NAION, an eye condition that can cause vision loss, is a very rare side effect of semaglutide, affecting up to 1 in 10,000 people.³ It advises contacting a doctor right away about sudden vision loss and stopping semaglutide if NAION is confirmed.³ The U.S. Ozempic label, revised in May 2026, does not list NAION.¹

Kidneys, gallbladder and severe gut reactions

After approval, acute kidney injury was reported in people on semaglutide, some cases needing dialysis, mostly in people dehydrated by nausea, vomiting or diarrhea.¹ The label says to monitor kidney function in these people, especially while the dose is started or raised.¹ Gallstones occurred in 1.5% on 0.5 mg and 0.4% on 1 mg in placebo-controlled trials, and in no one on placebo.¹ Severe stomach and gut reactions occurred in 0.4% and 0.8%, against 0% on placebo, and Ozempic is not recommended for people with severe gastroparesis (very slow stomach emptying).¹

Surgery, allergic reactions and pregnancy

Ozempic slows stomach emptying, and there are rare reports of food or liquid being breathed into the lungs during general anesthesia or deep sedation in people on GLP-1 drugs.¹ The label tells patients to inform their providers about Ozempic before any planned procedure.¹ Serious allergic reactions, anaphylaxis and angioedema, have been reported.¹ Human pregnancy data are limited and animal studies showed possible risks to the fetus.¹ Because semaglutide takes a long time to wash out, the label says to stop Ozempic at least 2 months before a planned pregnancy.¹ There are no data on semaglutide in human breast milk.¹

Who should not use Ozempic

The label rules it out for anyone with a personal or family history of medullary thyroid carcinoma, anyone with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2), and anyone who has had a serious allergic reaction to semaglutide or another ingredient.¹ Safety and effectiveness have not been established in people under 18.¹

Related pages

Back to What is Ozempic?. The label schedule is in Ozempic dosage, trial results in Ozempic benefits and uses, and pen handling in Ozempic injection sites and pen use. Side effects across the drug class: GLP-1 side effects.