Semaglutide Side Effects: The Complete List With How Common Each One Is

Most articles about semaglutide side effects give you a list of five things and no numbers. That is not very useful when you are trying to decide whether the queasiness you feel is normal or a reason to call someone.

This page works differently. It walks through every side effect that actually appears in the FDA prescribing information for Ozempic, Wegovy and Rybelsus, and puts the trial percentage next to it. Where a side effect is not in the label but has been studied, that is flagged too.

One thing to keep straight before you start: semaglutide is the active ingredient in Ozempic, Wegovy, Rybelsus, Ozempic tablets and Wegovy tablets. It is not the same drug as tirzepatide (Mounjaro, Zepbound), which is made by a different company and has its own label, or liraglutide (Victoza, Saxenda). Numbers from one do not transfer to another.

Nothing here is medical advice. It is a map of what the label and the published studies say, so you can have a better conversation with a healthcare provider.

What are the most common semaglutide side effects?

The stomach and gut account for almost everything on the common list. Semaglutide slows how fast the stomach empties, and it acts on brain regions that control appetite and nausea. Both of those are the point of the drug, and both cause the side effects.

Here is the Wegovy adult table, which covers the 2.4 mg once-weekly weight-management dose, compared with placebo [1]:

Side effect	Wegovy 2.4 mg	Placebo
Nausea	44%	16%
Diarrhea	30%	16%
Vomiting	24%	6%
Constipation	24%	11%
Abdominal pain	20%	10%
Headache	14%	10%
Fatigue	11%	5%
Indigestion (dyspepsia)	9%	3%
Dizziness	8%	4%
Bloating (abdominal distension)	7%	5%
Burping (eructation)	7%	under 1%
Low blood sugar in type 2 diabetes	6%	2%
Gas (flatulence)	6%	4%
Gastroenteritis	6%	4%
Acid reflux	5%	3%
Gastritis	4%	1%
Viral gastroenteritis	4%	3%
Hair loss	3%	1%
Skin sensitivity (dysesthesia)	2%	1%

The Ozempic numbers are lower, because the diabetes doses are lower. At 0.5 mg, nausea was 15.8%, vomiting 5%, diarrhea 8.5%, abdominal pain 7.3% and constipation 5%. At 1 mg, nausea rose to 20.3% and vomiting to 9.2% [2].

Oral semaglutide sits in between. At 14 mg daily, nausea was 20%, abdominal pain 11%, diarrhea 10%, decreased appetite 9%, vomiting 8% and constipation 5% [3].

Two patterns show up across every trial program. First, side effects are dose-related: the more semaglutide, the more nausea. Second, most reports of nausea, vomiting and diarrhea happen during dose escalation, not once someone has settled at a maintenance dose [1][2].

How often do side effects make people quit?

This is the single most useful number, because it collapses “how bad is it” into one figure.

• Wegovy 2.4 mg injection, adults: 6.8% stopped because of an adverse reaction, versus 3.2% on placebo. Stomach and gut problems specifically caused 4.3% versus 0.7% [1].
• Wegovy 25 mg tablets, adults: 6.9% versus 5.9% on placebo [1].
• Ozempic: 3.1% at 0.5 mg and 3.8% at 1 mg stopped because of gut problems, versus 0.4% on placebo [2].
• Oral semaglutide: 4% at 7 mg and 8% at 14 mg stopped because of gut problems, versus 1% on placebo [3].
• Adolescents aged 12 and older on Wegovy: 2.3% versus 1.5% on placebo [1].

The individual reactions that most often ended treatment on Wegovy were nausea (1.8% versus 0.2%), vomiting (1.2% versus 0%) and diarrhea (0.7% versus 0.1%) [1].

So the honest summary is: most people get gut side effects, most of those side effects are mild to moderate and fade, and roughly one in fifteen people finds them bad enough to stop.

What serious side effects does the semaglutide label warn about?

The Warnings and Precautions section is the part of the label that flags problems serious enough to change medical decisions. As of the May 2026 Ozempic label revision, there are ten [2]:

Thyroid C-cell tumors (boxed warning). Semaglutide caused dose-dependent thyroid C-cell tumors in mice and rats at exposures relevant to human dosing. Whether it does the same in humans is unknown. The label also says that routine calcitonin blood tests or thyroid ultrasound are of uncertain value for screening, because false positives can lead to unnecessary procedures [2]. On the human side, a 2026 analysis in Diabetes, Obesity and Metabolism concluded the available data do not suggest an association between semaglutide or liraglutide and thyroid cancer in adults [9]. Read that one with the authorship in view: the majority of its authors are employees of Novo Nordisk, which makes semaglutide. That does not make the finding wrong, and it is consistent with other published work, but it is not independent evidence.

Acute pancreatitis. Inflammation of the pancreas, including fatal and non-fatal hemorrhagic or necrotizing forms, has been seen with GLP-1 drugs. In the Ozempic glycemic trials, adjudicated pancreatitis occurred in 7 semaglutide-treated patients (0.3 cases per 100 patient-years) versus 3 in comparator groups. In the Wegovy weight trials, 4 cases (0.2 per 100 patient-years) versus 1 on placebo [1][2]. The warning symptom is persistent or severe abdominal pain, sometimes radiating to the back, with or without vomiting. On January 29, 2026 the UK regulator strengthened pancreatitis warnings across the whole GLP-1 class, after 1,296 Yellow Card reports of pancreatitis between 2007 and October 2025, of which 19 were fatal and 24 were reported as necrotizing. The MHRA put that alongside an estimated 25.4 million packs dispensed over five years. The FDA has not made a matching change [11].

Diabetic retinopathy complications. In a two-year cardiovascular trial in people with type 2 diabetes, these occurred in 3.0% on semaglutide versus 1.8% on placebo. The gap was much wider in people who already had retinopathy at the start: 8.2% versus 5.2%. In people with no known retinopathy, it was 0.7% versus 0.4% [1][2]. Rapid improvement in blood sugar is a known trigger for temporary worsening of retinopathy regardless of which drug produces it.

Hypoglycemia. Semaglutide by itself rarely causes dangerous lows in people without diabetes. Combined with insulin or a sulfonylurea, the picture changes. Adding Ozempic 1 mg to basal insulin produced documented symptomatic low blood sugar in 29.8% of people, versus 15.2% on placebo. With a sulfonylurea, severe hypoglycemia occurred in 0.8% at 0.5 mg and 1.2% at 1 mg [2].

Acute kidney injury from dehydration. There have been postmarketing reports, some requiring dialysis. The label notes that most occurred in people who became dehydrated from nausea, vomiting or diarrhea. In Wegovy trials, acute kidney injury occurred in 7 adults (0.4 per 100 patient-years) versus 4 on placebo [1][2].

Severe gastrointestinal adverse reactions. This warning was added to all semaglutide labels in October 2025. Severe gut reactions occurred in 4.1% of Wegovy-treated adults versus 0.9% on placebo, and 0.4% to 0.8% of Ozempic-treated patients versus 0% on placebo. The same section says semaglutide is not recommended in people with severe gastroparesis [1][2].

Hypersensitivity reactions. Anaphylaxis and angioedema have been reported. In the adult Wegovy trials, allergic reactions occurred in 16% of people who developed anti-semaglutide antibodies versus 7% of those who did not [1].

Acute gallbladder disease. Gallstones were reported by 1.6% of Wegovy injection users versus 0.7% on placebo, and by 2.5% of Wegovy tablet users versus 1%. Gallbladder inflammation was 0.6% versus 0.2%. In adolescents the rates were higher: gallstones 3.8% versus 0%. The label makes a point of saying the excess persists even after accounting for how much weight people lost [1].

Pulmonary aspiration during anesthesia. Rare postmarketing reports of food or fluid entering the lungs during procedures, in people who had food still in the stomach despite following fasting instructions. The label says available data are not sufficient to say how to reduce this risk [1][2]. There is a separate article on this site about surgery and semaglutide.

Never share a pen. Sharing an injection pen, even with a fresh needle, risks transmitting bloodborne infections. The Wegovy label added this for the four-dose FlexTouch pen in June 2026 [6].

The Wegovy label adds one more that Ozempic does not carry: resting heart rate increase. Mean increases were 1 to 4 beats per minute, but 26% of Wegovy-treated adults had a maximum rise of 20 beats per minute or more at some visit versus 16% on placebo, and in adolescents that figure was 54% versus 39% [1].

What about gastroparesis, ileus and bowel obstruction?

These are the injuries at the center of thousands of US lawsuits, so they deserve a straight answer.

Ileus, intestinal obstruction, severe constipation and fecal impaction all appear in the postmarketing section of every semaglutide label [2]. That section covers reactions reported voluntarily after approval, where the label explicitly says frequency cannot be reliably estimated. The FDA added ileus to the Ozempic label in September 2023.

Gastroparesis is different. It is not named as a discrete adverse reaction anywhere in the US label. The closest the label gets is the statement that semaglutide is not recommended in people with severe gastroparesis [2].

The most-cited outside evidence is a 2023 JAMA research letter comparing people who started a GLP-1 drug for weight loss against people who started bupropion-naltrexone. Per 1,000 person-years, gastroparesis occurred at 9.1 with semaglutide versus 3.1 with the comparator; pancreatitis at 4.6 versus 1.0. The adjusted hazard ratios were 3.67 for gastroparesis, 9.09 for pancreatitis and 4.22 for bowel obstruction [4]. Those are striking numbers, but the study included only 613 semaglutide users, and the confidence intervals are wide, which is why courts are still arguing about what it proves.

Does semaglutide cause hair loss?

Yes, at a low rate, and the current evidence points to a temporary type rather than permanent damage.

Hair loss appears in the Wegovy table at 3% versus 1% on placebo in adults, and 4% versus 0% in adolescents. In trial data, people who lost more than 20% of their body weight reported hair loss more often than those who lost less than 20%, at 5.3% versus 2.5% [1].

A BMJ study published July 22, 2026 used Penn Medicine electronic health records to compare adults with type 2 diabetes starting a GLP-1 drug against those starting other diabetes medicines, in a design called a target trial emulation. It found hazard ratios of 1.37 (95% CI 1.08 to 1.73) versus SGLT2 inhibitors and 1.68 (1.28 to 2.20) versus DPP-4 inhibitors for new hair loss. Subtype analysis pointed to non-scarring hair loss specifically, at 1.53 and 1.72 respectively [10]. That pattern fits telogen effluvium, the temporary shedding that follows rapid weight loss, major illness or nutritional shortfalls, and it is the type where the follicle survives and regrowth remains possible. That reassurance now needs a qualification. An NYU Langone genetic study published in the Journal of Investigative Dermatology on September 3, 2026 found that men with higher predicted GLP-1 receptor activity, inferred from GLP1R variants across databases covering more than 200,000 people, had a 7% higher risk of androgenetic alopecia — inherited pattern hair loss, which is not temporary and is mechanistically distinct from telogen effluvium — an association that held after adjusting for hypertension, insulin resistance and lower testosterone [12][13]. A 2026 TriNetX analysis likewise reported elevated odds of androgenetic alopecia (1.64) alongside telogen effluvium (1.76). At least part of this signal may be unmasking of pattern hair loss rather than reversible shedding; the genetic finding is male-only and does not itself demonstrate a follicle mechanism. (updated 2026-09-14)

The absolute numbers are worth holding onto: 6.91 cases per 1,000 person-years on a GLP-1 drug versus 5.04 on an SGLT2 inhibitor. The authors described the absolute risk as low, and noted that the FDA has said it is evaluating this potential signal [10].

What side effects are not on the label but people talk about?

“Ozempic face.” Not a diagnosis and not in any label. It describes the gaunt, hollowed look some people develop after fast weight loss. Published reviews attribute it to loss of facial fat plus skin that does not tighten as quickly as the fat disappears.

Muscle loss. Also not a labeled adverse reaction. The Wegovy label states that semaglutide lowers body weight with greater fat mass loss than lean mass loss [1], but absolute lean mass does fall, as it does with any large weight loss.

Alcohol feeling different. No labeled interaction exists. Two randomized trials have found that semaglutide reduces drinking, which is why many people report losing interest in alcohol.

Each of these has its own article on this site.

Are there side effects specific to the pill?

Yes, one notable one. In a trial of the 25 mg Wegovy tablet, 4.9% of people reported dysesthesia adverse reactions, meaning sensitive skin, heightened sensation, tingling, allodynia or a skin burning feeling, compared with 0% on placebo [1]. This is listed as a most-common reaction in the Wegovy Highlights.

The tablet also carries an absorption rule that has nothing to do with side effects but everything to do with whether it works: take it on an empty stomach in the morning with no more than 4 ounces of plain water, swallow it whole, and wait at least 30 minutes before any food, other drink or other oral medicine [3].

For breastfeeding, the label splits the two forms. Breastfeeding is not recommended on semaglutide tablets, because the absorption enhancer SNAC and its breakdown products are present in human milk and infants may clear SNAC more slowly. For the injection, there are no human milk data and the decision is framed as a benefit-risk discussion [1].

What are the rarer things in the trial data?

These show up in the adverse reactions section without rising to a formal warning [1]:

• Fractures. In the Wegovy cardiovascular outcomes trial, hip and pelvis fractures were reported in 1% of women on semaglutide versus 0.2% on placebo, and in 2.4% of people aged 75 and older versus 0.6%.
• Appendicitis, including perforated appendicitis: 0.5% versus 0.2%.
• Kidney stones: 1.2% versus 0.8%, with serious cases at 0.6% versus 0.4%.
• Low blood pressure and fainting: hypotension terms 1.3% versus 0.4%, fainting 0.8% versus 0.2%.
• Taste changes: 1.7% versus 0.5%.
• Raised amylase and lipase. Pancreatic enzymes rose an average 15% to 16% and 39% respectively on Wegovy. The label says the clinical meaning of these rises is unknown without other signs of pancreatitis, which is worth knowing before an isolated lab result causes alarm.
• Liver enzymes in adolescents. ALT rose to five times the upper limit of normal or higher in 3% of adolescents on Wegovy versus 0% on placebo, sometimes alongside gallstones.
• Injection site reactions: 1.4% versus 1%, which is unusually low for an injectable.

Which side effects have been studied and ruled out?

Two matter.

Suicidal thoughts and behavior. After three years of investigation, the FDA asked manufacturers on January 13, 2026 to remove the suicidal ideation and behavior warning from GLP-1 labels. The review covered 91 placebo-controlled trials with 107,910 patients (60,338 on a GLP-1 drug, 47,572 on placebo) plus a Sentinel System cohort of 2,243,138 users (1,161,983 starting a GLP-1 drug, 1,081,155 starting an SGLT2 inhibitor). The FDA said the results showed no increased risk of suicidal ideation or behavior, and no increase in anxiety, depression, irritability or psychosis [5].

One detail is easy to miss: only three products carried the warning in the first place, all of them weight-management drugs, namely Saxenda, Wegovy and Zepbound. The GLP-1 drugs approved for type 2 diabetes, Ozempic and Rybelsus among them, never had it. The Wegovy label recorded the removal in February 2026 [6]. Europe’s safety committee had reached the same conclusion in April 2024.

NAION, the sudden vision loss risk, has not been ruled out but has been quantified. In June 2025 the European Medicines Agency concluded that non-arteritic anterior ischemic optic neuropathy is a very rare side effect of semaglutide, affecting up to 1 in 10,000 people, and recommended adding it to European product information [7]. A February 2026 study of 102,361 US veterans with type 2 diabetes found weighted cumulative NAION risk of 0.29% with semaglutide versus 0.13% with a comparison drug class over a median of 2.1 years, a hazard ratio of 2.33 (95% CI 1.54 to 3.54) built on 173 events in total [8]. As of September 14, 2026, the FDA had not added a NAION warning to the US labels: a full read of the May 2026 Ozempic label and the June 2026 Wegovy label finds no mention of NAION or optic neuropathy anywhere [1][2].

When should someone contact a healthcare provider?

The labels flag a handful of situations as urgent rather than wait-and-see:

• Persistent or severe abdominal pain, especially if it spreads to the back, with or without vomiting: a possible sign of pancreatitis.
• Vomiting or diarrhea severe enough to stop you keeping fluids down, because dehydration is the route to kidney injury.
• Sudden loss of vision or rapidly worsening eyesight, which European regulators specifically ask patients to report immediately.
• A lump in the neck, trouble swallowing, shortness of breath or a hoarse voice that will not go away, which the boxed warning names as thyroid tumor symptoms.
• Swelling of the face, lips or throat, trouble breathing, or a widespread rash: possible severe allergic reaction.
• Palpitations or a racing heartbeat at rest.
• Signs of low blood sugar, especially if you also take insulin or a sulfonylurea.

Anyone planning surgery, an endoscopy, a colonoscopy or any procedure with sedation should tell the care team they are taking semaglutide, because the label specifically instructs patients to do so.

Side effect tables describe groups, not individuals. What any one person experiences, and whether the trade-off is worth it, is a conversation for them and their healthcare provider.

Sources

1. WEGOVY (semaglutide) Prescribing Information, NDA 215256 s033 — U.S. Food and Drug Administration, revised June 2026
2. OZEMPIC (semaglutide) injection label — DailyMed / Novo Nordisk, revised May 2026
3. RYBELSUS and OZEMPIC (semaglutide) tablets Prescribing Information — U.S. Food and Drug Administration, revised January 2026
4. Risk of Gastrointestinal Adverse Events Associated With GLP-1 Receptor Agonists for Weight Loss — JAMA, October 5, 2023
5. FDA Requests Removal of Suicidal Behavior and Ideation Warning from GLP-1 RA Medications — FDA Drug Safety Communication, January 13, 2026
6. WEGOVY injection and tablet label — DailyMed / Novo Nordisk, revised June 2026
7. PRAC concludes NAION is a very rare side effect of semaglutide medicines — European Medicines Agency, June 6, 2025
8. New-Onset NAION and Initiators of Semaglutide in US Veterans With Type 2 Diabetes — JAMA Ophthalmology, February 12, 2026
9. Assessment of thyroid cancer risk associated with GLP-1 receptor agonist use — Diabetes, Obesity and Metabolism, 2026
10. Risk of hair loss associated with GLP-1 receptor agonists: target trial emulation — The BMJ, July 22, 2026
11. GLP-1 receptor agonists: strengthened warnings on acute pancreatitis — UK MHRA Drug Safety Update, January 29, 2026
12. Some hair loss in men is linked to use of weight-loss drugs — NYU Langone Health via PR Newswire, September 3, 2026
13. GLP-1 hair loss and male pattern baldness study — NBC News, September 2026