Glucagon-like peptide-1 (GLP-1) medications have become one of the most discussed categories of prescription treatment for weight management. This guide explains what these medications are, how they work in the body, what approved products exist, what side effects are commonly reported, and what questions are worth asking a healthcare professional before considering one.
Better Weight Guide does not prescribe or sell medication. This article is educational only: whether any medication is appropriate for a specific person can only be determined through evaluation by a qualified healthcare professional.
What Are GLP-1 Medications?
GLP-1 receptor agonists are prescription medicines that mimic the action of glucagon-like peptide-1, a hormone released in the gut after eating. Several were first developed to treat type 2 diabetes, and some are also approved by the U.S. Food and Drug Administration (FDA) for weight management. Formulations include daily or weekly injections and, for Wegovy, a once-daily oral tablet. For weight management, Wegovy and Zepbound are labeled for use with a reduced-calorie diet and increased physical activity [1][2].
How They Work in the Body
GLP-1 receptor agonists act on several systems at once:
- Appetite regulation. They act on brain pathways involved in hunger and satiety, which tends to reduce calorie intake.
- Slower gastric emptying. These medicines can delay gastric emptying, which may contribute to fullness and can affect absorption of some oral medicines [1][2].
- Blood sugar effects. They support insulin release in a glucose-dependent way, which is one reason they were first used in type 2 diabetes.
The effect is reduced appetite and calorie intake rather than direct "fat burning." Prescribing information describes greater fat-mass loss than lean-mass loss and notes that decreased calorie intake contributes to weight reduction [1][2].
Approved Medications and Labeled Uses
In the United States, GLP-1-related medicines approved for long-term weight reduction in adults include products indicated for adults with obesity, or adults with overweight who have at least one weight-related condition, together with diet and physical activity [1][2][5]:
- Semaglutide (Wegovy) — a once-weekly injection; an oral tablet form has also been approved [1].
- Tirzepatide (Zepbound) — a once-weekly injection that activates both GIP and GLP-1 receptors [2].
Liraglutide (Saxenda) is another GLP-1 medicine approved for chronic weight management. Products such as Ozempic (semaglutide) and Mounjaro (tirzepatide) have different labeled uses, primarily for type 2 diabetes. Eligibility differs by product, and Wegovy and Zepbound are contraindicated in people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) [1][2][5]. A healthcare professional evaluates these factors case by case.
Commonly Reported Side Effects
Common adverse reactions listed for Wegovy and Zepbound are mainly gastrointestinal and include nausea, diarrhea, vomiting, constipation, abdominal pain, and indigestion. Prescribing information uses gradual dose escalation to reduce gastrointestinal reactions [1][2].
More serious risks and warnings in current prescribing information include pancreatitis, gallbladder disease, acute kidney injury due to volume depletion, severe gastrointestinal reactions, and a boxed warning about thyroid C-cell tumors observed in rodents [1][2]. The complete lists differ by product, so a healthcare professional should review the current prescribing information with you.
Approved Products vs. Compounded Versions
Some pharmacies and websites market compounded versions of semaglutide and tirzepatide. The FDA states that compounded drugs are not FDA-approved and are not reviewed by the agency for safety, effectiveness, or quality before marketing [3]. The FDA has also reported dosing errors involving compounded injectable semaglutide, including adverse events that sometimes required hospitalization [4].
A compounded drug is not an FDA-approved generic version. The FDA says compounded drugs should be used only when a patient's medical need cannot be met by an available FDA-approved drug. Ask whether the prescribed product is FDA-approved, who made it, and which licensed pharmacy will dispense it [3][4].
What the Evidence Does and Does Not Show
In clinical trials used for FDA approval, Wegovy and Zepbound produced greater average weight reduction than placebo when combined with diet and physical activity [1][2]. Averages describe study populations, not individuals: response and tolerability vary. NIDDK notes that people will probably regain some weight after stopping weight-management medication, so duration and discontinuation should be discussed with the prescribing clinician [5].
It is also worth being cautious about claims that a medication is appropriate for "most people." FDA labeling specifies the populations for whom a medicine is indicated, and a healthcare professional must weigh medical history, current medications, and personal goals before making any recommendation.
Frequently Asked Questions
Are GLP-1 medications right for everyone with weight concerns?
No. FDA-approved labeling defines specific populations and lists contraindications and precautions. Whether any medication is appropriate requires an individual evaluation by a qualified healthcare professional [1][2].
Do these medications replace diet and exercise?
No. Every FDA-approved use is in combination with a reduced-calorie diet and increased physical activity [1][2].
Can I buy GLP-1 medication without a prescription?
FDA-approved GLP-1 medicines are prescription drugs. The FDA has warned consumers about products sold illegally without a prescription and other unapproved GLP-1 products [3].
What happens when someone stops taking a GLP-1 medication?
NIDDK says people will probably regain some weight after stopping weight-management medication. Discuss duration, ongoing lifestyle support, and any discontinuation plan with the prescribing clinician [5].
This article is educational and is not medical advice, diagnosis, or treatment. Decisions about prescription medication require an evaluation by a qualified healthcare professional who knows your full medical history.