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Boxed warning

Wegovy has boxed warnings. These are the strongest warnings issued by the US Food and Drug Administration (FDA) about a drug’s potentially dangerous side effects.

Wegovy has the following two boxed warnings:¹

  • Animal studies have shown the drug causes thyroid C-cell tumors. At this time, it is unknown what relevance this has for cancer in humans.

  • The drug is contraindicated for people with a personal or family history of medullary thyroid carcinoma (MTC) or who have been diagnosed with multiple endocrine neoplasia syndrome type 2 (MEN2). Patients should be given guidance on how to look for typical thyroid tumor symptoms, such as difficulty swallowing, hoarse voice, and a lump in the neck area where the thyroid gland is located.

What is Wegovy?

Wegovy is a prescription medication that belongs to a group of drugs known as glucagon-like peptide-1 (GLP-1) agonists.

Wegovy contains semaglutide as its active ingredient, a compound that acts like a natural hormone the body produces after eating. It binds to the GLP-1 receptor, which triggers the brain to regulate your appetite and food intake. This can result in weight loss as your calorie intake is reduced.

What is Wegovy used to treat?

Wegovy was approved by the FDA for weight management in adults with:²

Dosage forms and strengths

Wegovy is available as a liquid solution inside pre-filled single-dose disposable injection pens.¹

It comes in the following strengths:

  • 0.25mg/0.5mL

  • 0.5mg/0.5mL

  • 1mg/0.5mL

  • 1.7mg/0.75mL

  • 2.4mg/0.75mL

At first, your doctor will likely recommend the lowest dosage: 0.25mg. You will inject this once a week for the first four weeks. Then, your doctor might increase the dose every four weeks (month) as follows:

  • 0.5mg once a week for the second month

  • 1mg once a week for the third month

  • 1.7mg once a week for month four

  • 2.4mg once a week for month five and beyond

How do you take Wegovy?

Wegovy is administered as an injection under the skin on the upper arm, thigh, or lower abdomen.

Your doctor will give you specific instructions on how to administer Wegovy at home. Try to follow their instructions closely for the best outcome.

The drug should be injected once per week on a specific day for the first four weeks.

Remember, each pen delivers a single dose of the solution, so every dose requires a new injectable pen.

When administering Wegovy, make sure to:¹

  • Wash your hands before injecting the drug

  • Clean the skin at the injection site with alcohol or soap and water, and allow the area to dry before injecting

  • Never remove the pen cap until ready to inject

  • Check that the needle is covered by the needle cover before use

  • Avoid touching or pushing the needle cover as you could develop a needle stick injury

  • Don’t remove the needle from your skin until the yellow bar inside the pen window stops moving

Seeing results

If you administer Wegovy as prescribed by your doctor, the injections start working within days of your first dose. However, since Wegovy works by mimicking the GLP-1 hormone (which regulates appetite in the brain), it may take several weeks to notice any substantial weight loss.

Who should not take Wegovy?

Wegovy should not be taken by you or a family member with a history of MTC, a type of thyroid cancer, or if you have MEN 2, a disease of the endocrine system.³

Patients with a history of pancreatitis are not usually candidates for treatment with GLP-1 receptor agonists.⁴

Anyone who has had a severe allergic reaction to semaglutide or any ingredients in Wegovy should not take the drug.

Do not take Wegovy with other GLP-1 agonists. Talk to your doctor about alternative medications suitable for your condition.

Wegovy should not be given to children.

Potential side effects of Wegovy

Side effects of Wegovy range from mild to severe. The more common side effects reported include:⁵

  • Nausea, vomiting

  • Diarrhea, constipation

  • Abdominal pain

  • Upset stomach, belching, bloated feeling, gas

  • Dizziness

  • Headache

  • Fatigue

  • Hair loss

Most of these side effects clear after a few days or weeks. Talk to your doctor if they last too long or worsen.

Severe adverse effects include the following:¹

  • Pancreatitis: Inflammation of the pancreas would typically manifest as diarrhea, vomiting, and persistent and worsening abdominal pain.

  • Gallbladder problems: Wegovy can cause gallstones and gallbladder inflammation. Symptoms would be severe abdominal pain, nausea, and vomiting. They may also include yellowing of the eyes and skin (jaundice) and fever.

  • Low blood sugar: This is more likely to occur in patients with type 2 diabetes, but it has been reported in others. Symptoms would include lightheadedness, rapid heart rate, shaking, sweating, and nausea.

  • Serious allergic reactions: Wegovy can cause skin rashes, hives, itchiness, and swelling at the injection site or anywhere on the body. Severe reactions can involve swelling of the face, tongue, or throat and even trouble breathing.

  • Low blood pressure: This effect is more likely to occur if you are being treated for high blood pressure (hypertension). Dizziness and fainting have been reported.

  • Acute kidney injury: This is a rare side effect, but it was reported more frequently in people with pre-existing kidney disease as doses were being increased.

  • Thyroid cancer: Wegovy’s boxed warning states there may be an increased risk of developing thyroid cancer.

  • Diabetic retinopathy: This condition can occur in people with diabetes and involves damage to the blood vessels supplying the retina. Symptoms include blurry vision, floaters, and vision loss.

  • Suicidal tendencies: Wegovy can cause changes in mood, thoughts, and behavior. Talk to your doctor if you feel depressed or you are considering harming yourself.

Taken correctly, Wegovy is safe and effective. Inform your doctor of any bothersome side effects or seek emergency medical attention if they are severe.


Administering more than the recommended dosage can lead to an overdose. Possible signs of Wegovy toxicity include:¹

If you suspect you have taken too much of this medication, call 911 or your doctor immediately. You can also contact the National Poison Control Center helpline at 1-800-222-1222.⁶

Allergy information

Various types of allergic reactions have been reported by patients after taking Wegovy. Signs range from mild to severe as follows:

Mild allergic reactions

Common allergic reactions to Wegovy include any of the following:

  • Skin rash, hives

  • Itchiness

  • Flushing 

Severe allergic reactions

Although rare, severe allergic reactions to Wegovy include any of the following:

  • Angioedema (swelling around the lips, tongue, throat, hands, eyelids, or feet)

  • Vomiting

  • Trouble breathing

  • Loss of consciousness

If you have signs of a mild allergic reaction, call your doctor right away as it could worsen. If your symptoms are very severe and seem life-threatening, call 911 or your local emergency number for immediate medical assistance.

Long-term use of Wegovy

Wegovy is often used as a long-term weight management drug. Your doctor may prescribe the medication for 30, 60, or 90 days continuously if it’s suitable for you.

It works best when combined with other weight management treatments and lifestyle changes, such as consuming a low-calorie diet and doing more exercise.

Wegovy and pregnancy

It remains unclear whether Wegovy is harmful to pregnant women.

No human studies have been carried out on pregnant women, but animal studies have shown harm can occur to the fetus at lower doses than those recommended for humans. Maternal weight loss may also have negative effects on a developing fetus.

If you plan to conceive, stop using Wegovy at least two months before a planned pregnancy. If you get pregnant while still taking Wegovy, tell your doctor so they can review the benefits and potential risks in your case to determine whether you should continue using it.¹

Wegovy and breastfeeding

There is not enough data to substantiate whether Wegovy can pass to an infant through breast milk. Therefore, the risks cannot be ruled out.

Talk to your doctor about the benefits and risks of taking Wegovy while breastfeeding.

Missed doses

If you miss one dose of Wegovy and you’re not scheduled to take the next dose for another 48 hours or more, take the missed dose immediately.

However, if your next dose is less than 48 hours away, skip your missed dose and take the next as scheduled.

Tell your doctor if you miss two or more doses. They may recommend a temporary dosage adjustment. Never take double doses and consider using a medication reminder app to alert you when it’s time to take the medication.¹

Drug interactions

Wegovy can interact with other medications you are taking. These include non-prescription and prescription drugs and herbal supplements.⁷

Any of the following types of drugs should be given with caution or at lower doses due to the risk of hypoglycemia:

  • Insulin, such as insulin glargine (Lantus), insulin, and degludec (Tresiba)

  • Sulfonylureas, such as glimepiride (Amaryl), chlorpropamide (Diabinese), and glipizide (Glucotrol)

  • Other diabetes medications, like dulaglutide (Trulicity), exenatide (Byetta), liraglutide (Victoza, Saxenda), nateglinide (Starlix), and repaglinide (Prandin)

  • Other medications, herbs, or supplements for weight loss

Can I drink alcohol while taking Wegovy?

Interactions between Wegovy and alcohol have not yet been confirmed. Some concerns have been noted related to hypoglycemia in patients with diabetes. Additionally, drinking alcohol may worsen some of the drug’s other side effects. Talk to your doctor about how much alcohol consumption is safe and stays within your weight loss plan during Wegovy treatment.

What to discuss with your doctor before starting Wegovy

Here are some topics to discuss with your doctor before taking Wegovy:

  • Any health issues you have, particularly pancreatic or kidney disease, type 2 diabetes, or a history of diabetic retinopathy

  • All medications you’re currently taking, including over-the-counter drugs, herbs, and supplements

  • Any history of medication allergies

  • Any harmful or suicidal thoughts or other mental health issues, such as depression

  • Any alcohol consumption or drug use

  • Pregnancy, contraception, and breastfeeding plans

Stopping Wegovy

Talk to your doctor before you stop taking Wegovy. Suddenly discontinuing Wegovy may cause weight loss outcomes.

Drug approval history

Wegovy proved to be effective in helping patients lose weight in clinical trials. In June 2021, the FDA approved Wegovy once-per-week injections for weight loss management when combined with low-calorie diets and exercise.⁴

Tips for taking Wegovy

Apply the following tips when taking Wegovy for the best results:

  • Read all of the instructions before starting your first injection

  • Take the drug on the same day each week

  • Never remove the pen cap unless you are ready to inject

  • Wash your hands and sterilize the site with an alcohol swab before injecting yourself with the drug

  • Set medication reminders to avoid missing doses

  • Check the expiration date before injecting your dose

  • Store your pens at room temperature in the original carton to protect them from light exposure

  • Talk to your doctor about any side effects or other concerns

  • Combine the drug with a low-calorie diet and exercise

Frequently asked questions

What if blood appears after I’ve injected myself?

If blood appears after administering Wegovy, hold pressure on the spot for 5–10 minutes using a cotton ball or gauze pad.

Is Wegovy covered by insurance?

Most insurance covers Wegovy, but check with your insurance provider to be sure.

Curious about clinical trials?

Access the latest treatments and medications. unavailable elsewhere - entirely free of charge. We make it easy to take part.

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Here at HealthMatch, we’ve done our best to ensure that the information provided in this article is helpful, up to date, and, most importantly, accurate.

However, we can’t replace the one-to-one advice of a qualified medical practitioner or outline all of the possible risks associated with this particular drug and your circumstances.

It is therefore important for you to note that the information contained in this article does not constitute professional medical or healthcare advice, diagnosis or recommendation of treatment and is not intended to, nor should be used to, replace professional medical advice. This article may not always be up to date and is not exhaustive of all of the risks and considerations relevant to this particular drug. In no circumstances should this article be relied upon without independent consideration and confirmation by a qualified medical practitioner.

Your doctor will be able to explain all possible uses, dosages, precautions, interactions with other drugs, and other potential adverse effects, and you should always talk to them about any kind of medication you are taking, thinking about taking or wanting to stop taking.

Curious about clinical trials?

Access the latest treatments and medications. unavailable elsewhere - entirely free of charge. We make it easy to take part.