Key takeaways
- GLP-1 is a natural gut hormone that helps control blood sugar and tells your brain you’re full.
- GLP-1 medicines (GLP-1 receptor agonists) copy that hormone and last much longer in the body.
- Semaglutide, liraglutide and tirzepatide are the best-known ingredients; tirzepatide also acts on a second hormone, GIP.
- They’re used for type 2 diabetes and weight management, and are taken as weekly or daily injections or a daily tablet.
- Your prescriber chooses the medicine and dose; tracking helps you see your progress and side effects clearly.
What GLP-1 is
GLP-1 stands for glucagon-like peptide-1. It’s a hormone released by your gut when food arrives. It helps your pancreas release insulin when blood sugar rises, lowers glucagon (a hormone that raises blood sugar), slows how quickly your stomach empties and sends “I’m full” signals to your brain. Your own GLP-1 is broken down within minutes, so its effect is short.
How GLP-1 medicines work
GLP-1 medicines, also called GLP-1 receptor agonists, act on the same receptors as your natural hormone but are designed to last for a day or a whole week. That longer effect is why many people notice a smaller appetite, feel full sooner and, for people with type 2 diabetes, see steadier blood sugar. Tirzepatide also acts on a second gut hormone receptor, GIP, which is why it’s sometimes called a dual agonist.
Most GLP-1 medicines start at a low dose that your prescriber increases step by step over several weeks. This gives your body time to adjust and helps keep side effects manageable.
GLP-1 medicines and brands
These are the most common GLP-1 and GLP-1/GIP medicines in the US and UK. Approvals differ between countries.
| Brand | Active ingredient | How often | Form | Main use (US) |
|---|---|---|---|---|
| Ozempic® | Semaglutide | Weekly | Injection pen | Type 2 diabetes |
| Wegovy® | Semaglutide | Weekly | Injection pen | Weight management |
| Rybelsus® | Semaglutide | Daily | Tablet | Type 2 diabetes |
| Mounjaro® | Tirzepatide (GIP + GLP-1) | Weekly | Pen or vial | Type 2 diabetes |
| Zepbound® | Tirzepatide (GIP + GLP-1) | Weekly | Pen or vial | Weight management, sleep apnea |
| Saxenda® | Liraglutide | Daily | Injection pen | Weight management |
| Victoza® | Liraglutide | Daily | Injection pen | Type 2 diabetes |
| Trulicity® | Dulaglutide | Weekly | Injection pen | Type 2 diabetes |
Compounded semaglutide and tirzepatide are made by compounding pharmacies. They are not FDA-approved, so only use them when a licensed clinician prescribes them and a licensed pharmacy supplies them. See our compounded GLP-1 tracker page.
What results to expect
In large clinical trials for weight management, adults taking semaglutide 2.4 mg lost an average of 14.9% of their body weight over 68 weeks (STEP 1), and adults taking tirzepatide 15 mg lost an average of 20.9% over 72 weeks (SURMOUNT-1). Both trials included diet and exercise support, and individual results varied widely. Your results depend on your medicine, your dose and your circumstances.
Common side effects
The most common side effects are digestive: nausea, constipation, diarrhoea, reflux and tiredness, especially after starting or stepping up a dose. For many people they ease over time. Read our guide to GLP-1 side effects for what often helps and which symptoms need urgent care.
Who GLP-1 medicines are not for
Your prescriber checks whether a GLP-1 is right for you. For example, the US labels carry a warning about a rare type of thyroid tumour, so these medicines aren’t used by people with a personal or family history of medullary thyroid cancer or MEN 2, and they’re generally not used in pregnancy. Always read the leaflet in your pack and ask your pharmacist if you have questions.
Tracking your treatment
A simple log makes appointments easier: the dose and day of each injection, where you injected, how you felt in the days after and how your weight, waist and strength are changing. Panda is a GLP-1 tracker app that does this in a few taps, and it never suggests or changes a dose.
Sources
- Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med 2021
- Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med 2022
- NHS: Semaglutide medicine guide
- MedlinePlus: Semaglutide injection
- DailyMed (US prescribing information for Ozempic®, Wegovy®, Mounjaro®, Zepbound®, Saxenda®, Rybelsus®)
This guide is general information, not medical advice, and doesn’t replace a conversation with your prescriber, pharmacist or doctor. Panda never suggests, calculates or changes a dose.
