Semaglutide Side Effects: What the FDA Labels Name

Quick answer

As of September 2026, the FDA-approved prescribing information for semaglutide lists eleven separate warnings and precautions on the label that covers the injection and the tablet approved for weight management, and nine on the label that covers the tablets approved for type 2 diabetes, and the reactions the labels name most often are gastrointestinal: nausea, vomiting, diarrhea, constipation and abdominal pain. Both labels also carry a boxed warning about thyroid C-cell tumors seen in rodents, and both name a smaller group of symptoms that mean calling a clinician immediately or seeking emergency care, including ongoing upper stomach pain that spreads to the back, swelling of the face, mouth, tongue or throat, decreased urination, and vision changes.

Which semaglutide labels this guide is built from

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist. Every safety statement below comes from the FDA-approved prescribing information for two semaglutide products, read through the openFDA label API on September 23, 2026, and from the plain-language patient pages the National Library of Medicine publishes for the same molecule.

The first, effective June 18, 2026, covers semaglutide injection and a semaglutide tablet used for weight management. Alongside a reduced calorie diet and increased physical activity, it is approved for cardiovascular risk reduction in adults with cardiovascular disease and obesity or overweight, for long term weight reduction in defined groups of adults and, for the injection, in patients aged 12 years and older with obesity, and for noncirrhotic metabolic dysfunction-associated steatohepatitis with moderate to advanced liver fibrosis in adults, an indication the label states was granted under accelerated approval, with continued approval possibly contingent on a confirmatory trial. The injection areas that label lists, and why injection sites are rotated, are covered in where to inject semaglutide.

The second, effective January 30, 2026, covers oral semaglutide tablets, approved to improve glycemic control in adults with type 2 diabetes and to reduce major adverse cardiovascular events in those at high risk for them.

Both carry a limitation worth reading first: taking a semaglutide product together with another semaglutide-containing product, or with any other GLP-1 receptor agonist, is not recommended.

The boxed warning, in plain words

A boxed warning is the strongest warning the FDA requires on a prescription label, and on semaglutide it concerns the thyroid. In mice and rats, semaglutide caused thyroid C-cell tumors, and the effect grew with higher exposure and with longer treatment. Whether it causes thyroid C-cell tumors, including medullary thyroid carcinoma, in people is unknown, because the relevance of the rodent finding to humans has not been determined. The label says that plainly rather than reassuringly.

What the warning asks of a patient is specific: learn the symptoms of a thyroid tumor and report them. A mass or swelling in the neck. Trouble swallowing. Shortness of breath. Hoarseness that does not go away.

The label also tells clinicians something patients rarely hear. Routine monitoring of serum calcitonin, or routine thyroid ultrasound, is of uncertain value for early detection here, and may increase the risk of unnecessary procedures. If you have asked for a screening ultrasound and been told it is not indicated, that is why.

Who should not take semaglutide?

Both labels list the same contraindications. Semaglutide is contraindicated in anyone with a personal or family history of medullary thyroid carcinoma, in anyone with Multiple Endocrine Neoplasia syndrome type 2, and in anyone who has had a prior serious hypersensitivity reaction to semaglutide or to any ingredient in the product. Serious hypersensitivity reactions, including anaphylaxis and angioedema, have been reported.

One more group sits just outside that list. Both labels state that semaglutide is not recommended in patients with severe gastroparesis, because the medicine slows stomach emptying.

The side effects the labels name

Here is the full named list, with no number attached to any of it, because a figure from a trial table is not a prediction about one person.

The weight management label names as its most common adverse reactions: nausea, diarrhea, vomiting, constipation, abdominal pain, dysesthesia (a change in skin sensation), headache, fatigue, dyspepsia (indigestion), dizziness, abdominal distension, eructation (burping), hypoglycemia in patients with type 2 diabetes, flatulence, gastroenteritis, gastroesophageal reflux disease, and hair loss.

The type 2 diabetes tablet label names as its most common adverse reactions: nausea, abdominal pain, diarrhea, decreased appetite, vomiting and constipation.

Decreased appetite deserves a note rather than an apology. It is listed as an adverse reaction, and it is also part of how the medicine works: semaglutide slows the emptying of the stomach and may decrease appetite. Feeling full sooner is expected. Being unable to keep fluids down is not, and that difference is worth learning early.

Three items on that list have their own pages: headache, hair shedding and constipation.

Gastrointestinal reactions, dehydration and your kidneys

This is the chain the labels draw, and the most useful thing to carry away from any page on semaglutide side effects.

First: gastrointestinal adverse reactions with semaglutide are sometimes severe. Severe is the label's own word, and severe gastrointestinal reactions have also been reported after approval.

Second: prolonged vomiting and diarrhea cause volume depletion.

Third: there have been postmarketing reports of acute kidney injury, in some cases requiring hemodialysis, and the majority of those reported events occurred in patients who had gastrointestinal reactions leading to dehydration.

That is why the label instructs clinicians to monitor kidney function in patients reporting reactions that could lead to volume depletion, especially while treatment is being started and while the dose is being increased, and why it instructs patients to avoid fluid depletion and to promptly report nausea, vomiting or diarrhea that persists. Fluids are not a tip on this page. Keeping them down, and saying so when you cannot, is what stands between a rough week and a kidney problem.

What are the most serious semaglutide side effects?

The weight management label carries eleven. The type 2 diabetes tablet label carries nine. Together they are the map of what a prescriber is watching for.

Risk of thyroid C-cell tumors. Covered above.

Acute pancreatitis. Including hemorrhagic or necrotizing pancreatitis that has sometimes been fatal, observed in patients treated with GLP-1 receptor agonists. The symptom to know is persistent or severe abdominal pain, sometimes radiating to the back, with or without nausea or vomiting. Semaglutide is to be discontinued if pancreatitis is suspected.

Acute gallbladder disease. Treatment is associated with an increased occurrence of gallstones and gallbladder inflammation, and the label notes the increase was seen even after accounting for the degree of weight loss. If it is suspected, gallbladder studies and clinical follow-up are indicated.

Hypoglycemia. Semaglutide lowers blood glucose and can cause low blood sugar, and the risk rises when it is used with insulin or an insulin secretagogue such as a sulfonylurea. All patients are to be told the risk and taught the signs.

Acute kidney injury due to volume depletion and severe gastrointestinal adverse reactions. Both covered above, with the instruction that semaglutide is not recommended in severe gastroparesis.

Hypersensitivity reactions. Serious reactions including anaphylaxis and angioedema have been reported. Discontinue and seek medical advice promptly.

Diabetic retinopathy complications in patients with type 2 diabetes. Rapid improvement in glucose control has been associated with a temporary worsening of retinopathy, and patients with a history of it should be monitored for progression.

Heart rate increase. Clinicians monitor heart rate at regular intervals, patients report palpitations or a racing heartbeat at rest, and a sustained increase is a reason to discontinue.

Pulmonary aspiration during general anesthesia or deep sedation. Its own section below.

Never share an injection pen between patients, even if the needle is changed, because pen sharing carries a risk of transmitting blood-borne pathogens.

Reactions reported after approval

Postmarketing reports arrive voluntarily from a population of uncertain size, so, as both labels state, it is not always possible to reliably estimate their frequency or to establish that the medicine caused them. They are still the list a reader wants, because they include the rarer events trials were too small to catch.

Reported after approval: acute pancreatitis and necrotizing pancreatitis, sometimes resulting in death; ileus; intestinal obstruction; severe constipation including fecal impaction; anaphylaxis; angioedema; rash; urticaria; acute kidney injury; and pulmonary aspiration during procedures requiring general anesthesia or deep sedation. The tablet label adds cholecystitis and gallstones requiring gallbladder removal, dizziness, dysesthesia, dysgeusia (a change in taste), headache, and alopecia.

Ileus and intestinal obstruction are the reason constipation is not always a nuisance symptom.

Medicines that interact with semaglutide

Two interaction categories appear on both labels.

The first is hypoglycemia. Used together with insulin or an insulin secretagogue such as a sulfonylurea, semaglutide increases the risk of low blood sugar, including severe low blood sugar. The labels tell prescribers to consider reducing the dose of the insulin or the secretagogue when semaglutide is started. That is a prescriber's decision, never a patient's own adjustment.

The second is absorption. Semaglutide delays gastric emptying, which can change how the body absorbs other medicines taken by mouth. The labels tell clinicians to consider increased clinical or laboratory monitoring for oral medicines with a narrow therapeutic index. In a drug interaction study with the semaglutide tablet, levothyroxine exposure was increased when the two were taken together, and levothyroxine is the example the label names.

The practical version: bring a complete list of everything you take, including nonprescription products, to every appointment.

Injection and tablet: what changes

Route changes part of the picture and none of the core. The core is identical: same boxed warning, same contraindications, same warnings for pancreatitis, gallbladder disease, hypoglycemia, kidney injury after volume depletion, severe gastrointestinal reactions, hypersensitivity, retinopathy complications and pulmonary aspiration.

What differs is at the edges. The weight management label adds heart rate increase, which applies to both of the products it covers, and the instruction never to share a pen, which applies only to the injection. The type 2 diabetes tablet carries administration conditions the injection does not: taken on an empty stomach, with water only and no more than four ounces of it, swallowed whole without splitting, crushing or chewing, and nothing else, not food, not other drinks, not other oral medicines, for at least thirty minutes afterward. Absorption depends on those conditions. A tablet taken with coffee has not been taken as labeled.

Missed doses are also handled differently for the injection and the tablet, and differently again depending on what the medicine was prescribed for. That rule lives in the patient labeling supplied with the product.

When should you call your clinician, and when is it an emergency?

Three tiers, from the patient labeling and the counseling section.

Tell your clinician if it is severe or does not go away: nausea, vomiting, diarrhea, stomach pain, constipation, heartburn, burping, runny nose or sore throat, headache.

Call immediately or get emergency medical treatment: ongoing pain that begins in the upper left or middle of the stomach and may spread to the back, with or without vomiting; rash, itching, fainting or dizziness, swelling of the eyes, face, mouth, tongue or throat, or difficulty breathing or swallowing; decreased urination, or swelling of the legs, ankles or feet; vision changes; pain in the upper stomach with yellowing of the skin or eyes, fever or clay-colored stools; a rapid or pounding heartbeat; severe stomach or intestinal problems.

Call immediately for the boxed warning symptoms: a lump or swelling in the neck, hoarseness, difficulty swallowing, or shortness of breath.

For a suspected overdose, the poison control helpline is 1-800-222-1222. If someone has collapsed, had a seizure or cannot be woken, call 911.

Before any surgery, procedure or sedation

Semaglutide delays gastric emptying. There have been rare postmarketing reports of pulmonary aspiration in patients receiving GLP-1 receptor agonists who underwent elective surgery or a procedure requiring general anesthesia or deep sedation and had food still in the stomach despite reported adherence to preoperative fasting instructions.

The label is honest that available data are insufficient to say whether changing fasting instructions or temporarily stopping the medicine would reduce that risk. What it does instruct is simple: tell every provider, before any planned surgery or procedure, that you take semaglutide. The patient labeling extends that to dental surgery.

If you also have type 2 diabetes

Two things change.

Low blood sugar becomes a daily consideration, especially alongside insulin or a sulfonylurea. The signs, in the patient labeling's own plain words: dizziness or lightheadedness, irritability, sweating, hunger, drowsiness, shakiness, weakness, headache, slurred speech, blurred vision, a fast heart rate and feeling jittery. Episodes of hypoglycemia have also been reported with GLP-1 receptor agonists in adults without type 2 diabetes, so learning the signs is not only for people with diabetes.

Eyes need watching, because rapid improvement in glucose control has been associated with a temporary worsening of diabetic retinopathy. Any change in vision is a reason to contact a physician.

The patient labeling also says to ask what to do on a sick day, during an infection or fever, or when diet, exercise or weight changes substantially.

How long do semaglutide side effects last?

Neither FDA-approved label publishes a timeline, and no honest page can supply one it does not have. What the labels do give is the shape of the answer.

On the drug itself: the weight management label reports an elimination half-life of approximately one week and states that semaglutide will be present in the circulation for about five to seven weeks after the last injectable dose. That is pharmacology, not a forecast of how you will feel, but it explains why a reaction does not stop on the day the medicine stops.

On the reactions: the labels tie kidney monitoring and the most common reactions to the period when treatment begins and to the periods when a prescriber changes what is prescribed. Reactions cluster around those moments rather than arriving at random.

On what not to wait out: nausea, vomiting and diarrhea were the most common reactions leading people to stop treatment in trials, and the labels instruct patients to promptly report gastrointestinal symptoms that are severe or persistent, because the labels tie persistent vomiting and diarrhea to dehydration and to reports of acute kidney injury. Duration is a question a clinician answers for one person, not a number a page can print.

How a physician manages side effects, as a process

There is no list of household remedies here, and that is deliberate. What a clinician does is a sequence of decisions, and knowing it tells you what a visit is for.

The first decision is pace. The labels tie both kidney monitoring and the most common reactions to the period when treatment begins and to the periods when a prescriber changes what is prescribed. Pace is not a self-care setting. It is a prescribing decision, and asking to move faster is asking for the reactions to arrive sooner.

The second is whether to hold, step back or advance. When reactions are severe or persistent, the patient reports them and the prescriber decides: stay at the current step longer, reduce, or stop.

The third is what gets checked: kidney function when reactions could cause volume depletion, heart rate at regular intervals, blood glucose in patients with diabetes, gallbladder studies if gallbladder disease is suspected, and retinal monitoring for anyone with a history of diabetic retinopathy.

The fourth is when a clinician stops the medicine outright. The labels name the triggers plainly: suspected pancreatitis, a hypersensitivity reaction, and a sustained increase in resting heart rate. The patient labeling adds the other half of that rule: do not stop semaglutide without talking to your doctor.

More on management, and the class-wide view across the drug class, is at managing GLP-1 side effects.

Compounded semaglutide and side effects: what the FDA has actually said

Almost no page answers this from a primary source, so here it is from the agency's own page on unapproved GLP-1 drugs used for weight loss, content current as of September 1, 2026.

The starting point: compounded drugs are not FDA approved, and the agency does not review them for safety, effectiveness or quality before they are marketed.

On adverse events. As of May 31, 2026 the FDA had received 990 reports of adverse events associated with compounded semaglutide. It states directly that federal law does not require state-licensed pharmacies that are not outsourcing facilities to submit adverse events to the FDA, so events from compounded versions are likely underreported, and it notes that many of the events reported for compounded products appear to be consistent with those related to the FDA-approved versions. Those are counts of voluntary reports, not rates.

On dosing. The agency received multiple reports of adverse events, some requiring hospitalization, that may relate to dosing errors with compounded injectable semaglutide, from patients measuring and self-administering incorrect doses and, in some cases, from health care professionals miscalculating doses. It also received reports that may relate to patients prescribed doses beyond what the FDA-approved label describes.

On ingredients. Some semaglutide products sold by compounders may be salt forms, such as semaglutide sodium and semaglutide acetate, which the agency states are different active ingredients than the one used in the approved drugs.

On labels and shipping. The FDA is aware of compounded semaglutide marketed with false information on the product label, including labels naming pharmacies that do not exist or that did not compound the product. It has also received complaints that certain compounded GLP-1 drugs arrived warm or with inadequate ice packs, and it recommends not using any injectable GLP-1 drug that arrives warm or insufficiently refrigerated.

For a reader: know which pharmacy compounded your medicine, check the label against that pharmacy, do not use a product that arrives warm, and never adjust a dose on your own.

How to report a side effect

Tell the prescribing clinician first, because that is the person who can act on it.

Then report it to the FDA. Both labels print the route: the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. The patient labeling gives the same MedWatch program with the number 1-800-332-1088 and an online form. Patient reports are how the postmarketing lists above came to exist, and for a compounded product, reporting is often the only way a problem reaches the agency.

Questions to bring to your appointment

Copy this list and take it with you.

• Does anyone in my family have thyroid cancer, medullary thyroid carcinoma or MEN 2?
• Have I ever had pancreatitis, gallbladder disease or kidney disease?
• Do I have gastroparesis, other severe stomach problems, or trouble digesting food?
• Do I have, or have I ever had, diabetic retinopathy?
• Here is every medicine, vitamin and supplement I take. Does any of them need extra monitoring?
• Am I pregnant, breastfeeding or planning a pregnancy, and how far ahead should I stop?
• Do I have any surgery, procedure or dental work scheduled?
• What should I do on a sick day, or if I cannot keep fluids down?
• What exactly should I call about, and when does it become an emergency?
• Which pharmacy compounded my medicine, and what do I do if the package arrives warm?

Related reading

• GLP-1 side effects across the class, and managing them
• Semaglutide and constipation
• Hair shedding on GLP-1 treatment
• Semaglutide headaches
• Help center

Sources

1. Prescribing information, semaglutide injection and tablets, DailyMed set id ee06186f-2aa3-4990-a760-757579d8f77b, effective June 18, 2026.
2. Prescribing information, oral semaglutide tablets, DailyMed set id 27f15fac-7d98-4114-a2ec-92494a91da98, effective January 30, 2026.
3. Semaglutide Injection, MedlinePlus patient drug information, last revised May 15, 2026.
4. Semaglutide oral tablet, MedlinePlus patient drug information, last revised March 15, 2026.
5. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss, U.S. Food and Drug Administration, content current as of September 1, 2026.

This article is for informational purposes only and does not constitute medical advice. Medication is prescribed only if a licensed physician determines it is appropriate. Compounded medications are not FDA-approved as final products.