Semaglutide Side Effects: Complete List of Common and Serious Reactions
The most common semaglutide side effects are digestive: nausea affected 44% of adults on Wegovy 2.4 mg versus 16% on placebo. Serious risks include pancreatitis, gallbladder disease, kidney injury, and a rare eye condition called NAION.
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Semaglutide’s most common side effects are digestive: nausea, diarrhea, vomiting, constipation, and abdominal pain. In the FDA label for Wegovy 2.4 mg injection, nausea was reported by 44% of adults taking the drug versus 16% on placebo, and diarrhea by 30% versus 16% [6]. Most of these reactions hit during the weeks when the dose is being raised, and 6.8% of adults on Wegovy 2.4 mg stopped the drug permanently because of side effects, compared with 3.2% on placebo [6].
The serious risks are less common but matter more. The labels carry warnings for inflammation of the pancreas, gallbladder disease, low blood sugar, acute kidney injury, severe digestive reactions, allergic reactions, diabetic retinopathy complications, and food or liquid entering the lungs during anesthesia [6, 2]. The Wegovy label also carries a warning on increases in resting heart rate [6]. A boxed warning covers thyroid C-cell tumors seen in rodents [6, 2]. European regulators have also classified a rare eye condition, NAION, as a very rare side effect [7].
Which products contain semaglutide?
Semaglutide comes as Wegovy injection and Wegovy tablets, used for weight management, cardiovascular risk reduction, and MASH (a liver disease), and as Ozempic injection for type 2 diabetes [6, 2]. Rybelsus tablets come in 3 mg, 7 mg, and 14 mg strengths, and Ozempic tablets come in 1.5 mg, 4 mg, and 9 mg strengths; the labels state these tablets are not substitutable on a mg-to-mg basis [3].
Semaglutide is a GLP-1 receptor agonist that delays gastric emptying, which is why so many of its side effects involve the digestive tract [6]. One caution applies to everything below: the labels state that adverse reaction rates from clinical trials cannot be directly compared across drugs or across studies, because trials run under different conditions [6]. So the Wegovy, Ozempic, and Rybelsus numbers that follow describe separate trials, not a head-to-head contest.
How common are Wegovy side effects?
The Wegovy 2.4 mg injection figures come from three placebo-controlled trials in adults with obesity or overweight: 2,116 people took Wegovy 2.4 mg and 1,261 took placebo, for up to 68 weeks [6].
| Side effect | Placebo | Wegovy 2.4 mg |
|---|---|---|
| Nausea | 16% | 44% |
| Diarrhea | 16% | 30% |
| Vomiting | 6% | 24% |
| Constipation | 11% | 24% |
| Abdominal pain | 10% | 20% |
| Headache | 10% | 14% |
| Fatigue | 5% | 11% |
| Dyspepsia (indigestion) | 3% | 9% |
| Dizziness | 4% | 8% |
| Abdominal distension | 5% | 7% |
| Eructation (belching) | <1% | 7% |
| Hypoglycemia in type 2 diabetes | 2% | 6% |
| Flatulence | 4% | 6% |
| Gastroenteritis | 4% | 6% |
| GERD (acid reflux) | 3% | 5% |
| Gastritis | 1% | 4% |
| Viral gastroenteritis | 3% | 4% |
| Hair loss | 1% | 3% |
| Dysesthesia (altered skin sensation) | 1% | 2% |
All figures are from the Wegovy label [6].
How common are Ozempic side effects at each dose?
The Ozempic injection figures come from pooled placebo-controlled trials in adults with type 2 diabetes [2].
| Side effect | Placebo | Ozempic 0.5 mg | Ozempic 1 mg |
|---|---|---|---|
| Nausea | 6.1% | 15.8% | 20.3% |
| Vomiting | 2.3% | 5% | 9.2% |
| Diarrhea | 1.9% | 8.5% | 8.8% |
| Abdominal pain | 4.6% | 7.3% | 5.7% |
| Constipation | 1.5% | 5% | 3.1% |
Pooled gastrointestinal reactions of any kind occurred in 15.3% of placebo patients, 32.7% on 0.5 mg, and 36.4% on 1 mg [2]. In a separate trial, 34% of patients on the 2 mg dose reported gastrointestinal reactions versus 30.8% on 1 mg [2].
What are the side effects of Rybelsus and Ozempic tablets?
The semaglutide tablet figures come from placebo-controlled trials in adults with type 2 diabetes [3].
| Side effect | Placebo | 7 mg tablets | 14 mg tablets |
|---|---|---|---|
| Nausea | 6% | 11% | 20% |
| Abdominal pain | 4% | 10% | 11% |
| Diarrhea | 4% | 9% | 10% |
| Decreased appetite | 1% | 6% | 9% |
| Vomiting | 3% | 6% | 8% |
| Constipation | 2% | 6% | 5% |
Overall gastrointestinal reactions occurred in 41% of patients on 14 mg, 32% on 7 mg, and 21% on placebo; severe gastrointestinal reactions were reported by 2.0% on 14 mg, 0.6% on 7 mg, and 0.3% on placebo [3].
Are side effects worse at the higher 7.2 mg Wegovy dose?
Yes, in the trials that tested it. Wegovy 7.2 mg injection was studied in two 72-week trials with 303 placebo patients, 304 patients on 2.4 mg, and 1,311 patients on 7.2 mg [6].
| Side effect | Placebo | Wegovy 2.4 mg | Wegovy 7.2 mg |
|---|---|---|---|
| Nausea | 13% | 35% | 39% |
| Vomiting | 6% | 16% | 22% |
| Dysesthesia | 0% | 6% | 22% |
| Constipation | 8% | 19% | 20% |
| Hair loss | 1% | 3% | 6% |
Dysesthesia — a group of altered skin sensations that includes burning, tingling, and sensitive skin — rose with dosage and with blood levels of the drug [6]. Among 38 patients who recovered from dysesthesia and were re-escalated to 7.2 mg, 17 (45%) reported it again [6].
How severe are the side effects, and how many people stop the drug?
Across the adult weight-loss trials, 73% of Wegovy injection patients reported a gastrointestinal reaction of some kind, versus 47% on placebo; severe gastrointestinal reactions were reported by 4.1% versus 0.9% [6]. The label states these reactions were most frequently reported during dose escalation [6].
Permanent discontinuation for any adverse reaction occurred in 6.8% of adults on Wegovy 2.4 mg versus 3.2% on placebo [6]. Gastrointestinal reactions alone led 4.3% of Wegovy patients to stop, versus 0.7% on placebo; the leading single causes were nausea (1.8% vs 0.2%), vomiting (1.2% vs 0%), and diarrhea (0.7% vs 0.1%) [6].
For Ozempic injection, gastrointestinal reactions led 3.1% of patients on 0.5 mg and 3.8% on 1 mg to stop treatment, versus 0.4% on placebo [2]. For the tablets, the discontinuation figures were 4% on 7 mg, 8% on 14 mg, and 1% on placebo [3]. In the adolescent trial, 2.3% stopped for gastrointestinal reactions versus 1.5% on placebo [6]. In the large cardiovascular outcomes trial, where safety collection was limited, 16% of Wegovy patients stopped study drug due to an adverse event versus 8% on placebo [6].
What is the thyroid C-cell tumor warning about?
Every semaglutide label carries a boxed warning stating that in rodents the drug causes dose- and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures, and that it is unknown whether it causes such tumors, including medullary thyroid carcinoma, in humans [2, 6]. Because of this, semaglutide is contraindicated in anyone with a personal or family history of medullary thyroid carcinoma, or with Multiple Endocrine Neoplasia syndrome type 2 [2]. The labels list thyroid tumor symptoms to watch for: a mass in the neck, trouble swallowing, shortness of breath, and persistent hoarseness, and state that routine calcitonin monitoring or thyroid ultrasound is of uncertain value [2].
A large human analysis published in Diabetes, Obesity and Metabolism on November 25, 2025 examined 93 Novo Nordisk trials with 101,732 participants [9]. Across all trials, the hazard ratio for thyroid cancer was 1.70 (95% CI 0.99–3.03) versus placebo, and an analysis of the US MarketScan database found a hazard ratio of 0.87 (95% CI 0.58–1.29) versus SGLT2 inhibitors; the authors concluded the data did not suggest an association in adults [9]. Six of the nine listed authors are affiliated with Novo Nordisk A/S, the maker of semaglutide [9].
Can semaglutide cause pancreatitis?
Yes, it is a labeled warning. In Wegovy adult weight-loss trials, adjudicated acute pancreatitis occurred in 4 patients on the drug (0.2 cases per 100 patient-years) versus 1 on placebo [6]. In Ozempic glycemic control trials, it was confirmed in 7 patients (0.3 per 100 patient-years) versus 3 in comparator groups [2].
The warning symptoms are persistent or severe abdominal pain, sometimes radiating to the back, with or without nausea and vomiting; the label states that Wegovy should be discontinued if pancreatitis is suspected [6]. Postmarketing reports include necrotizing pancreatitis, sometimes fatal [6, 2]. In January 2026, the UK’s MHRA reported that class-wide product information had been strengthened after rare necrotizing and fatal reports, advised that treatment not be restarted if pancreatitis is confirmed, and urged caution in patients with a history of pancreatitis [11].
On lab values: Wegovy trials showed mean amylase increases of 15% to 16% and lipase increases of 39%, but the label states the clinical significance of these elevations is unknown in the absence of other signs and symptoms of pancreatitis [6].
Does semaglutide cause gallbladder problems?
Gallstones were reported by 1.6% of adults on Wegovy injection versus 0.7% on placebo, and by 2.5% on Wegovy tablets versus 1% on placebo; cholecystitis (gallbladder inflammation) occurred in 0.6% versus 0.2% on the injection [6]. In adolescents, gallstones were reported by 3.8% on Wegovy versus 0% on placebo, and cholecystitis by 0.8% versus 0% [6]. The label notes the excess persisted even after accounting for the degree of weight loss [6].
Does semaglutide cause low blood sugar or kidney injury?
The labels state that the risk of hypoglycemia increases when semaglutide is used together with insulin or an insulin secretagogue such as a sulfonylurea, and the Wegovy label says to inform all patients of the risk and its signs and symptoms [6, 2]. In a Wegovy trial of adults with type 2 diabetes, glucose below 54 mg/dL occurred in 6.2% on Wegovy versus 2.5% on placebo [6]. When Ozempic was added to basal insulin, documented symptomatic hypoglycemia occurred in 29.8% on the 1 mg dose, 16.7% on 0.5 mg, and 15.2% on placebo; when combined with a sulfonylurea, severe hypoglycemia occurred in 0.8% on 0.5 mg and 1.2% on 1 mg [2].
Acute kidney injury occurred in 7 Wegovy patients in the weight-loss trials (0.4 per 100 patient-years) versus 4 on placebo (0.2) [6]. Postmarketing reports include kidney injury, some requiring hemodialysis, with most cases following gastrointestinal reactions that caused dehydration [2].
Can semaglutide affect your eyes?
Two separate issues appear here. First, in a 2-year trial of patients with type 2 diabetes and high cardiovascular risk, diabetic retinopathy complications occurred in 3% on semaglutide injection versus 1.8% on placebo; among patients with existing retinopathy the rates were 8.2% versus 5.2%, and among those without, 0.7% versus 0.4% [6]. The label states separately that rapid improvement in glucose control has been associated with a temporary worsening of diabetic retinopathy [6].
Second is NAION, a condition that can cause sudden vision loss. On June 6, 2025, the European Medicines Agency’s safety committee concluded NAION is a very rare side effect of semaglutide, meaning it may affect up to 1 in 10,000 people taking it [7]. EMA also reported that several large epidemiological studies suggest roughly a two-fold increase in NAION risk in adults with type 2 diabetes exposed to semaglutide, corresponding to approximately one additional case per 10,000 person-years of treatment [7]. A study in JAMA Ophthalmology of 102,361 US veterans with type 2 diabetes found NAION in 0.29% of semaglutide initiators versus 0.13% of SGLT2 inhibitor users over a median 2.1 years, with 173 events and a hazard ratio of 2.33 (95% CI 1.54–3.54) [8]. NAION is not among the Warnings and Precautions headings in the US Wegovy (6/2026) or Ozempic (5/2026) labels [6, 2].
What about heart rate, allergic reactions, and anesthesia?
Wegovy raised resting heart rate by an average of 1 to 4 beats per minute in adult trials; a rise of 20 beats per minute or more at any visit occurred in 26% of adults on Wegovy versus 16% on placebo, and in 54% versus 39% of adolescents [6].
Anaphylaxis and angioedema have been reported with semaglutide [6]. In adult trials, allergic reactions occurred in 16% of patients who developed anti-semaglutide antibodies versus 7% of those who did not [6].
There have been rare postmarketing reports of pulmonary aspiration — food or liquid entering the lungs — in patients undergoing general anesthesia or deep sedation despite following fasting instructions; the labels instruct patients to tell healthcare providers about planned surgeries or procedures [6]. The Ozempic label also states never to share an Ozempic pen between patients, even with a needle change, and a matching Wegovy FlexTouch warning was added in June 2026 [2, 6].
Can semaglutide cause bowel obstruction or gastroparesis?
The postmarketing sections of the labels list ileus, intestinal obstruction, and severe constipation including fecal impaction; because these reports are voluntary, the labels state their frequency cannot be reliably estimated [6, 2]. The labels also state semaglutide is not recommended in patients with severe gastroparesis, under a Severe Gastrointestinal Adverse Reactions warning dated October 2025 [6, 2].
A 2023 JAMA research letter using claims data compared 613 semaglutide users, 4,144 liraglutide users, and 654 users of bupropion-naltrexone, a weight-loss drug unrelated to GLP-1s [4]. Gastroparesis occurred at 9.1 per 1,000 person-years in semaglutide users versus 3.1 with the comparator, and pancreatitis at 4.6 versus 1.0 [4]. The adjusted hazard ratios, however, were calculated for the pooled GLP-1 group (semaglutide plus liraglutide) versus bupropion-naltrexone: pancreatitis 9.09 (95% CI 1.25–66.00), bowel obstruction 4.22 (1.02–17.40), and gastroparesis 3.67 (1.15–11.90) [4]. The semaglutide group was small and the confidence intervals are wide, so these numbers are imprecise [4].
Does semaglutide cause hair loss?
Hair loss was reported by 3.3% of adults on Wegovy 2.4 mg versus 1% on placebo in pooled trials — 4% of women and 0.9% of men on the drug — and by 5.8% on the 7.2 mg dose (8.4% of women, 0.2% of men); in adolescents it was 4% versus 0% [6]. The label links hair loss to weight reduction [6].
A BMJ study published July 22, 2026, using Penn Medicine records of adults with type 2 diabetes, found GLP-1 receptor agonist use associated with alopecia versus SGLT2 inhibitors (hazard ratio 1.37, 95% CI 1.08–1.73) and versus DPP-4 inhibitors (1.68, 1.28–2.20), with adjusted rates of 6.91 versus 5.04 per 1,000 person-years [10]. The signal was specific to non-scarring alopecia (hazard ratios 1.53 and 1.72), events clustered in the first year, and the authors point to telogen effluvium, a form often described as reversible; they note the absolute risk is low [10].
A separate NYU Langone genetic study announced September 3, 2026, found that men genetically at risk of androgenetic alopecia had a 7% added risk associated with a genetic proxy for GLP-1 receptor activity, a finding that held after accounting for insulin resistance and testosterone, and that applied to men only [12, 13]. This was a genetic proxy study described in a press release, not a trial of people taking the drug [12].
What side effects are more common in women?
Hair loss is the clearest example: 4% of women on Wegovy 2.4 mg reported it versus 0.9% of men [6]. In the cardiovascular outcomes trial, hip and pelvis fractures were reported in 1% of women on Wegovy versus 0.2% of women on placebo [6].
On pregnancy: the label states Wegovy may cause fetal harm and should be discontinued when pregnancy is recognized for weight or cardiovascular use, and discontinued at least 2 months before a planned pregnancy because of semaglutide’s long half-life [6, 2]. For the tablets, breastfeeding is not recommended: the absorption enhancer SNAC is present in human milk, and infants may clear SNAC more slowly than adults [6, 3].
What about the tablets specifically?
In the Wegovy 25 mg tablet trial, dysesthesia was reported by 5% versus 0% on placebo, and severe gastrointestinal reactions by 2% versus 0% [6]. The tablet labels instruct patients to take them on an empty stomach in the morning with up to 4 ounces of water, swallow them whole, and wait at least 30 minutes before food, drink, or other oral medicines [3, 6]. Because semaglutide delays gastric emptying, it may affect the absorption of other oral medicines [6, 3].
What less common side effects appear in the trial data?
The Wegovy label also lists, in adults: hip and pelvis fractures in patients age 75 and older (2.4% vs 0.6%), appendicitis including perforated (0.5% vs 0.2%), kidney stones (1.2% vs 0.8%, with serious cases 0.6% vs 0.4%), altered taste (1.7% vs 0.5%), hypotension-related reactions (1.3% vs 0.4%), and syncope (0.8% vs 0.2%), with low blood pressure reactions more common in patients on blood-pressure medicines [6]. Injection site reactions occurred in 1.4% versus 1% [6]. In adolescents, liver enzyme (ALT) rises of five times the upper limit of normal occurred in 3% versus 0% [6].
Was the suicidal thoughts warning removed?
Yes. On January 13, 2026, the FDA requested removal of the suicidal behavior and ideation warning from GLP-1 medications that carried it — only Saxenda, Wegovy, and Zepbound did; the diabetes GLP-1 labels never had it [5]. The decision followed a meta-analysis of 91 placebo-controlled trials with 107,910 patients that found no increased risk of suicidal ideation or behavior, anxiety, depression, irritability, or psychosis, and a Sentinel cohort study of 2,243,138 users versus SGLT2 inhibitor users that found no increased risk of intentional self-harm [5]. The Wegovy label shows the removal dated February 2026 [6]. The FDA still asks patients to report new or worsening depression, and points to the 988 line for anyone in distress [5].
Who should not take semaglutide?
The labels list three contraindications: a personal or family history of medullary thyroid carcinoma, MEN 2, and a serious hypersensitivity reaction to semaglutide or any of its excipients [2, 6]. Beyond the contraindications, the labels state semaglutide is not recommended in severe gastroparesis, and that combining it with other semaglutide products or any other GLP-1 receptor agonist is not recommended [6]. The labels also advise monitoring for patients with a history of diabetic retinopathy, and note a higher hypoglycemia risk for people on insulin or sulfonylureas [6, 2].
Which symptoms need prompt medical attention?
The labels and regulators point to a short list. Severe, persistent abdominal pain that may radiate to the back, with or without nausea and vomiting, is the pancreatitis warning sign [6, 11]. Sudden vision loss or rapidly worsening eyesight is the NAION symptom flagged by the European Medicines Agency [7]. A mass in the neck, trouble swallowing, shortness of breath, or persistent hoarseness are thyroid tumor symptoms; swelling of the face or throat signals a hypersensitivity reaction; and a racing heartbeat while at rest is listed under the heart rate warning [2, 6]. Side effects can be reported to the FDA MedWatch program at 1-800-FDA-1088 [6, 5].
Sources
- US Food and Drug Administration. WEGOVY (semaglutide) injection and tablets prescribing information. 2026.
- National Library of Medicine DailyMed. OZEMPIC (semaglutide) injection, solution.
- US Food and Drug Administration. RYBELSUS and OZEMPIC (semaglutide) tablets prescribing information. 2026.
- JAMA. Risk of gastrointestinal adverse events associated with glucagon-like peptide-1 receptor agonists for weight loss.
- US Food and Drug Administration. FDA requests removal of suicidal behavior and ideation warning from glucagon-like peptide-1 receptor agonist (GLP-1 RA) medications.
- National Library of Medicine DailyMed. WEGOVY (semaglutide) injection, solution and tablet.
- European Medicines Agency. PRAC concludes eye condition NAION is a very rare side effect of semaglutide medicines Ozempic, Rybelsus and Wegovy.
- JAMA Ophthalmology. New-onset nonarteritic anterior ischemic optic neuropathy and initiators of semaglutide in US veterans with type 2 diabetes.
- Diabetes, Obesity and Metabolism. Assessment of thyroid cancer risk associated with glucagon-like peptide 1 receptor agonist use. 2026.
- BMJ. Risk of hair loss associated with glucagon-like peptide-1 receptor agonists in adults with type 2 diabetes: target trial emulation. July 22, 2026.
- GOV.UK. GLP-1 receptor agonists and dual GLP-1/GIP receptor agonists: strengthened warnings on acute pancreatitis, including necrotising and fatal cases.
- PR Newswire. Some hair loss in men is linked to use of weight loss drugs. September 3, 2026.
- NBC News. Hair loss on GLP-1 medications can be more than temporary for some men, study finds.
Frequently asked questions
How long do semaglutide side effects last, and when do they peak?
The labels state that gastrointestinal reactions such as nausea, vomiting, and diarrhea are most frequently reported during dose escalation — the weeks when the dose is being stepped up [6, 2]. In the tablet trials, the majority of nausea, vomiting, and diarrhea reports also occurred during dose escalation. How long any one person's symptoms last is individual, so persistent symptoms are worth discussing with a healthcare provider.
Are semaglutide side effects worse at higher doses?
In the trials, yes. Wegovy 7.2 mg produced more nausea (39% vs 35%), vomiting (22% vs 16%), dysesthesia (22% vs 6%), and hair loss (6% vs 3%) than the 2.4 mg dose. Ozempic 1 mg showed more nausea than 0.5 mg (20.3% vs 15.8%), and the 14 mg tablet more than the 7 mg tablet (20% vs 11%) [2, 3].
Are semaglutide side effects different in women?
Hair loss was reported more often by women in the Wegovy trials: 4% of women versus 0.9% of men at the 2.4 mg dose, and 8.4% of women at 7.2 mg. In the cardiovascular outcomes trial, hip and pelvis fractures occurred in 1% of women on Wegovy versus 0.2% on placebo. The label also states Wegovy may cause fetal harm and should be stopped when pregnancy is recognized.
How do Rybelsus side effects compare with the injection?
The tablet trials in type 2 diabetes showed nausea in 20% at 14 mg and 11% at 7 mg, versus 20.3% at Ozempic 1 mg injection — but the labels state trial rates cannot be directly compared across products or studies [3, 2, 6]. Both forms share the same digestive effects, and the tablets add strict dosing rules: empty stomach, water only, and a 30-minute wait before food or other oral medicines.
Can semaglutide cause pancreatitis?
Yes, it is a labeled warning. Adjudicated cases were rare in trials: 4 Wegovy patients (0.2 per 100 patient-years) versus 1 on placebo, and 7 Ozempic patients (0.3 per 100 patient-years) versus 3 comparators [6, 2]. Postmarketing reports include necrotizing pancreatitis, sometimes fatal, and the UK regulator strengthened class warnings in January 2026 [6, 2, 11].
Is semaglutide hair loss permanent?
The labels do not describe it as permanent and link it to weight reduction. A 2026 BMJ study found the signal was specific to non-scarring alopecia, with events clustered in the first year, and the authors point to telogen effluvium, a form often described as reversible, while noting the absolute risk is low. A genetic proxy study in men found a 7% added risk linked to androgenetic alopecia risk, but that was not a trial of drug users.
Can semaglutide cause vision loss?
The European Medicines Agency concluded in June 2025 that NAION, an eye condition that may cause vision loss, is a very rare side effect, affecting up to 1 in 10,000 people. EMA also reported that epidemiological studies suggest a roughly two-fold risk increase in adults with type 2 diabetes, about one extra case per 10,000 person-years. A JAMA Ophthalmology study found NAION in 0.29% of semaglutide users versus 0.13% on SGLT2 inhibitors, hazard ratio 2.33.
Does semaglutide cause thyroid cancer?
The boxed warning is based on rodent tumors, and the labels state human relevance has not been determined [2, 6]. A 2025 analysis of 93 Novo Nordisk trials with 101,732 participants found a trial hazard ratio of 1.70 (95% CI 0.99–3.03) versus placebo and 0.87 (0.58–1.29) versus SGLT2 inhibitors in the MarketScan data, concluding no suggested association in adults; six of the nine listed authors are affiliated with Novo Nordisk A/S.
This article summarizes FDA labeling, published research and company information current as of September 14, 2026. It is not medical advice and does not replace a conversation with your own healthcare provider. How we research and verify.