What Are Semaglutide Injections?
Semaglutide injections are a once-weekly prescription medicine, injected under the skin, that mimics the hormone GLP-1 to help control blood sugar and support weight loss. Injectable semaglutide is sold as Ozempic, Wegovy and Wegovy HD.
Wegovy is approved for long-term weight management, alongside a reduced-calorie diet and more physical activity. Ozempic is the semaglutide brand approved for type 2 diabetes. Semaglutide helps control diabetes and weight but does not cure either.
Semaglutide Injections at a Glance
| Brand names | Ozempic, Wegovy, Wegovy HD |
|---|---|
| Drug class | GLP-1 receptor agonist |
| What it treats | Type 2 diabetes; obesity or overweight; heart attack, stroke and death risk in certain adults with heart disease; worsening kidney disease in certain adults with type 2 diabetes; a liver disease called MASH |
| How it's given | A pen injection in the stomach area, thigh or upper arm, once a week on the same day |
| How long it's taken | Long term. Most people regain some weight after stopping. |
| Common side effects | Nausea, diarrhea, vomiting, constipation, stomach pain, headache |
| Boxed warning | Thyroid C-cell tumors in rodents. Not for people with a personal or family history of medullary thyroid cancer or MEN 2. |
| FDA status | FDA-approved (Ozempic, Wegovy). Compounded versions are not FDA-approved. |
Who Can Take Semaglutide Injections for Weight Loss?
Semaglutide injections for weight loss are meant for adults with a body mass index (BMI) of 30 or higher, or 27 or higher with a weight-related problem such as high blood pressure or type 2 diabetes. Wegovy is also approved for children 12 and older with obesity. The NIH advises never taking a weight management medicine only to improve your looks. These medicines work best alongside healthy eating and physical activity.
How Do Semaglutide Injections Work?
Semaglutide injections work by copying GLP-1, a hormone that targets the brain areas that control appetite and food intake. Semaglutide also:
- Helps the pancreas release the right amount of insulin when blood sugar is high
- Slows the emptying of the stomach
- May decrease appetite, which leads to weight loss
How Are Semaglutide Injections Taken?
Semaglutide injections are taken once a week, any time of day, with or without meals. The dose starts low and rises slowly, which helps limit stomach side effects:
- Starting dose: Wegovy starts at 0.25 mg weekly for 4 weeks, then increases every 4 weeks.
- Maintenance: for adults, the weight-loss dose is 2.4 mg weekly (recommended) or 1.7 mg. Adults who tolerate 2.4 mg for at least 4 weeks and need more weight loss may go up to a maximum of 7.2 mg (Wegovy HD).
- Injection sites: use a different spot each time.
- Missed dose (weight loss): take it within 48 hours, or skip it if the next dose is under 48 hours away.
- Storage: refrigerate pens (36°F to 46°F), don't freeze them, and never share a pen.
How Much Weight Can You Lose With Semaglutide Injections?
In the STEP 1 trial, semaglutide injections led to an average weight loss of about 15% over 68 weeks. The trial randomly assigned 1,961 adults with overweight or obesity, but without diabetes, to semaglutide 2.4 mg weekly or placebo, plus a lifestyle program:
- Average weight change was −14.9%, versus −2.4% with placebo.
- 86.4% lost at least 5%, 69.1% lost at least 10%, and 50.5% lost at least 15% of their weight.
Most weight loss with these medicines happens in the first 6 months. The American Diabetes Association's 2026 Standards of Care note that in people with type 2 diabetes and overweight or obesity, losing 5% to 7% of body weight improves blood sugar and other heart risk factors. In a trial of more than 17,600 adults with heart disease and overweight or obesity, heart attack, stroke or cardiovascular death occurred in 6.5% on Wegovy versus 8% on placebo.
Side Effects and Warnings
The most common semaglutide side effects affect the digestive system. The Obesity Medicine Association reports nausea in about 44% of people taking semaglutide, diarrhea in 30%, and vomiting and constipation in 24% each. In STEP 1, these effects were typically short-lived and mild to moderate.
Serious Risks on the FDA Label
- Pancreatitis (inflamed pancreas)
- Gallbladder problems, including gallstones
- Low blood sugar when used with insulin or other medicines that make the body release insulin
- Kidney injury from dehydration
- Severe stomach and bowel side effects
- Serious allergic reactions
- Diabetic eye disease complications in people with type 2 diabetes
- Faster heart rate
- Inhaling stomach contents during anesthesia, so tell your surgeon or dentist
Who Shouldn't Take Semaglutide?
- People with a personal or family history of medullary thyroid cancer or MEN 2
- Anyone allergic to semaglutide
- People already using another GLP-1 medicine
- People with severe gastroparesis
- People who are pregnant. Stop at least 2 months before a planned pregnancy.
Semaglutide Injections vs. Tirzepatide and Compounded Semaglutide
| What it is | FDA-approved? | Key difference | |
|---|---|---|---|
| Semaglutide injection (Wegovy, Ozempic) | Weekly GLP-1 injection | Yes | About 15% average weight loss in STEP 1 |
| Tirzepatide (Zepbound, Mounjaro) | Weekly injection that mimics GIP and GLP-1 | Yes | In a 72-week head-to-head trial in adults with obesity but without type 2 diabetes, 20.2% average weight loss versus 13.7% with semaglutide |
| Compounded semaglutide | Pharmacy-made version | No | Not reviewed by the FDA for safety, effectiveness or quality |
The FDA has received reports of dosing errors with compounded semaglutide, and the American Diabetes Association recommends against compounded versions.
Semaglutide Injections at GENEVA
At GENEVA Primary Care & Med Spa in Alpharetta, GA, a provider evaluates your weight, health history, medicines and goals. Based on that evaluation, your provider recommends treatment at GENEVA or a referral to a specialist.
Learn more about medical weight loss care and semaglutide injection evaluations at GENEVA. GENEVA serves patients from Alpharetta, Johns Creek, Milton, Roswell and Cumming.
Related Terms
- GLP-1 Receptor Agonist
- Semaglutide Titration Schedule
- Wegovy
- Ozempic
- Compounded Semaglutide
- Tirzepatide Injections
- Body Mass Index (BMI)
- Insulin Resistance
Semaglutide Injections FAQs
How much weight can you lose on semaglutide injections?
People taking semaglutide injections lost about 15% of their body weight on average in the STEP 1 clinical trial. In STEP 1, 1,961 adults with overweight or obesity and without diabetes received semaglutide 2.4 mg weekly or placebo, plus a lifestyle program, for 68 weeks. Average weight change was −14.9% with semaglutide versus −2.4% with placebo, and about half lost at least 15%. If you haven't lost at least 5% after 12 weeks on the full dose, your clinician will probably suggest stopping or changing your plan.
How long does semaglutide take to work?
Semaglutide injections take several months to reach the full dose, and most weight loss happens within the first 6 months. Wegovy starts at 0.25 mg once a week and increases every 4 weeks until you reach the maintenance dose, usually 2.4 mg. Clinicians usually judge whether it is working after 12 weeks on the full dose, looking for at least 5% weight loss. Don't raise the dose faster than directed.
What are the most common side effects of semaglutide?
The most common side effects of semaglutide are nausea, diarrhea, vomiting, constipation and stomach pain. The Obesity Medicine Association reports nausea in about 44% of people taking semaglutide, diarrhea in 30%, and vomiting and constipation in 24% each. In the STEP 1 trial, these effects were typically short-lived and mild to moderate, and most side effects of weight management medicines improve with continued use. Get medical help right away for ongoing upper stomach pain that spreads to your back.
What happens when you stop taking semaglutide?
You will probably regain weight after stopping semaglutide, which is why researchers suggest ongoing treatment to keep the benefits. In the STEP 1 extension, people who stopped semaglutide 2.4 mg and their lifestyle program regained two-thirds of the weight they had lost within one year. Improvements in heart risk factors also drifted back toward baseline. Talk with your clinician before stopping, and keep healthy eating and activity habits, which may help limit regain.
Is compounded semaglutide the same as Wegovy or Ozempic?
No, compounded semaglutide is not the same as Wegovy or Ozempic, because compounded versions are not FDA-approved. The FDA does not review compounded drugs for safety, effectiveness or quality before they are sold. The FDA has received reports of dosing errors, some needing hospital care, and warns that salt forms such as semaglutide sodium are different active ingredients. The American Diabetes Association recommends against compounded GLP-1 products. Fill any prescription at a state-licensed pharmacy.
What is the difference between Ozempic and Wegovy?
Ozempic and Wegovy both contain semaglutide, but they are approved for different uses and doses. Ozempic is the semaglutide brand approved for type 2 diabetes. Wegovy is approved for long-term weight management in people 12 and older with obesity and in adults with overweight plus a weight-related health problem, and to lower heart attack and stroke risk in adults with heart disease and obesity or overweight. Don't use the two together, because the Wegovy label says combining semaglutide products isn't recommended.
Can a primary care provider prescribe semaglutide injections?
Yes, a primary care provider can evaluate you for semaglutide injections and prescribe them when appropriate. The usual threshold is a BMI of 30 or higher, or 27 or higher with a problem such as high blood pressure or type 2 diabetes. At GENEVA in Alpharetta, your provider reviews your health history, medicines and goals, then recommends treatment at GENEVA or a referral to a specialist. Mention any family history of thyroid cancer, past pancreatitis or pregnancy plans.