GLP-1 Medications for Weight Management: A Beginner's Guide

If you are new to GLP-1 medications, start with the pairs: Wegovy and Ozempic share one active ingredient, and Zepbound and Mounjaro share another. What differs is what each product is approved to treat.

Short version

• Wegovy and Ozempic contain semaglutide, described in their labeling as a GLP-1 receptor agonist, while Zepbound and Mounjaro contain tirzepatide, described as a GIP and GLP-1 receptor agonist (Wegovy PI; Zepbound PI; Ozempic PI; Mounjaro PI).

• Wegovy and Zepbound are indicated to reduce excess body weight and maintain weight reduction long term, and Ozempic and Mounjaro are indicated to improve glycemic control in type 2 diabetes (Wegovy PI; Zepbound PI; Ozempic PI; Mounjaro PI).

• Wegovy is described as an injection or tablets, and the other three as injections (Wegovy PI; Zepbound PI; Ozempic PI; Mounjaro PI).

• All four carry the same boxed warning and the same core contraindications (Wegovy PI; Zepbound PI; Ozempic PI; Mounjaro PI); whether one is appropriate for a particular person is a decision for a licensed clinician.

What GLP-1 medications are

GLP-1 medications are prescription medicines that their labeling describes as receptor agonists acting on hormone pathways. Semaglutide is the active ingredient in Wegovy and Ozempic, and tirzepatide in Zepbound and Mounjaro (Wegovy PI; Zepbound PI; Ozempic PI; Mounjaro PI). Each approved use is tied to lifestyle measures: Wegovy and Zepbound are indicated with a reduced-calorie diet and increased physical activity (Wegovy PI; Zepbound PI).

Brand names and active ingredients

Each entry follows that product's own labeling.

• Wegovy (semaglutide; described in its labeling as a GLP-1 receptor agonist): Weight reduction and long-term maintenance; reducing the risk of major cardiovascular events in adults with established cardiovascular disease and either obesity or overweight (injection and tablets); noncirrhotic MASH with moderate to advanced liver fibrosis (injection only).

• Ozempic (semaglutide; GLP-1 receptor agonist): Glycemic control in adults with type 2 diabetes; reducing the risk of major cardiovascular events in adults with type 2 diabetes and established cardiovascular disease; reducing the risk of sustained eGFR decline, end-stage kidney disease, and cardiovascular death in adults with type 2 diabetes and chronic kidney disease

• Zepbound adds abdominal pain, dyspepsia, injection site reactions, fatigue, hypersensitivity reactions, eructation, hair loss, and gastroesophageal reflux disease (Zepbound PI).

• Mounjaro (tirzepatide; GIP and GLP-1 receptor agonist): Glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes

Sources for this list: (Wegovy PI; Zepbound PI; Ozempic PI; Mounjaro PI). To compare the two active ingredients, see Semaglutide vs Tirzepatide: What Are the Differences?.

Injections and pills

Wegovy's labeling covers both an injection for subcutaneous use and tablets for oral use, while Ozempic, Zepbound, and Mounjaro are described as injections for subcutaneous use (Wegovy PI; Zepbound PI; Ozempic PI; Mounjaro PI). For a fuller comparison, see Oral vs Injectable GLP-1 Options.

What the labeling says about who they are for and who they are not for

The approved populations differ. Wegovy's weight-management indication includes adults and pediatric patients aged 12 years and older with obesity, and adults with overweight plus a weight-related condition; Zepbound's covers adults with obesity or overweight with a weight-related condition (Wegovy PI; Zepbound PI). Ozempic's and Mounjaro's indications are in type 2 diabetes, with Mounjaro's also including pediatric patients 10 years and older (Ozempic PI; Mounjaro PI).

All four carry the same boxed warning, describing thyroid C-cell tumors in rodents with human relevance unknown, and all four are contraindicated in patients with a personal or family history of medullary thyroid carcinoma or MEN 2 (Wegovy PI; Mounjaro PI). They state the medications are not recommended in patients with severe gastroparesis, and they list warnings including acute pancreatitis, acute gallbladder disease, and acute kidney injury due to volume depletion (Wegovy PI; Zepbound PI).

For the questions a provider works through, see Who Shouldn't Take GLP-1 Medications?.

Common side effects at a glance

Each labeling lists the reactions reported in at least 5% of patients in clinical trials; nausea, diarrhea, vomiting, and constipation appear on all four lists (Wegovy PI; Zepbound PI; Ozempic PI; Mounjaro PI).

The lists also include other reactions that differ by product. Examples from each label (not complete lists):

• Wegovy adds abdominal pain, headache, fatigue, dyspepsia, dizziness, eructation, and hypoglycemia in patients with type 2 diabetes (Wegovy PI).

• Zepbound adds abdominal pain, dyspepsia, injection site reactions, fatigue, and hypersensitivity reactions (Zepbound PI).

• Ozempic adds abdominal pain (Ozempic PI).

• Mounjaro adds decreased appetite, dyspepsia, and abdominal pain (Mounjaro PI).

The labelings' warnings sections describe the serious risks (Wegovy PI; Zepbound PI); our guide to GLP-1 Side Effects covers what to watch for and when to contact a provider.

FDA-approved vs compounded

A compounded drug is not an FDA-approved drug. FDA states that it does not verify the safety, effectiveness, or quality of compounded drugs before they are marketed, and that compounded drugs should only be used in patients whose medical needs cannot be met by an FDA-approved drug (FDA: Compounding and the FDA). FDA adds that unapproved versions of GLP-1 drugs do not undergo its review for safety, effectiveness and quality before they are marketed (FDA: Concerns with unapproved GLP-1 drugs).

FDA has also described concerns specific to compounded GLP-1 products, including reports of dosing errors with compounded injectable semaglutide and fraudulent products carrying false label information (FDA: Concerns with unapproved GLP-1 drugs).

FDA recommends obtaining a prescription from your doctor and filling it at a state-licensed pharmacy (FDA: Concerns with unapproved GLP-1 drugs); our guide to FDA-Approved vs Compounded GLP-1 Medications covers the differences in more detail.

What a telehealth provider does and does not do

A telehealth program is a clinical service, and the clinical decisions belong to a licensed clinician. HHS advises patients to write down instructions during the visit, reach out to the provider's office with questions afterward, and follow up as needed; a provider may recommend next steps such as another appointment, a test, or medication (HHS: What happens after my telehealth visit?).

FDA lists warning signs for telehealth consumers, including a company that does not require screening and a prescription by a licensed doctor before providing medicine, and it states that prescription drug promotion must be truthful, non-misleading and accurate (FDA: Concerns with unapproved GLP-1 drugs; FDA: Compounding and the FDA). For what to look for, see What Makes a Legitimate GLP-1 Telehealth Provider? and What Happens After You Sign Up.

How long treatment lasts

Wegovy and Zepbound are indicated to reduce excess body weight and maintain weight reduction long term (Wegovy PI; Zepbound PI), so the weight-management labeling is written around longer-term use.

In an extension of the STEP 1 trial, participants regained weight on average in the year after semaglutide and lifestyle intervention were withdrawn (STEP 1 trial extension). In SURMOUNT-4, participants who continued tirzepatide maintained and added to their earlier weight reduction, while those who switched to placebo regained weight (SURMOUNT-4).

How long treatment continues for one person is a clinical decision; our guide to How Long Does GLP-1 Treatment Last? covers the labeling language and trial findings.

Questions to ask before you start

These questions are worth asking before any treatment decision:

• Is the product FDA-approved or compounded, and if compounded, why? (FDA-Approved vs Compounded)

• Which licensed clinician reviews my information, and how do I reach them afterward? (Legitimate Provider Guide)

• What does the price include, and what happens if it changes? (GLP-1 Costs Explained)

• What should I do if I have side effects, and how quickly will someone respond? (GLP-1 Side Effects)

Bottom line

Four brand names, two active ingredients, different approved uses: Wegovy and Ozempic contain semaglutide, and Zepbound and Mounjaro contain tirzepatide (Wegovy PI; Zepbound PI; Ozempic PI; Mounjaro PI). All four carry the same boxed warning and core contraindications, and all four are indicated for use alongside diet and exercise (Wegovy PI; Mounjaro PI).

Compounded versions are not FDA-approved; FDA says they should only be used when a patient's medical needs cannot be met by an FDA-approved drug (FDA: Compounding and the FDA).

Whether a GLP-1 medication is appropriate for you, and how long you take it, are decisions for a licensed clinician. Our GLP-1 myths guide covers claims that circulate widely, including the idea that these medications are only for diabetes.