Medically reviewed by Dr. Payman Joseph, MD · Updated November 2026
Semaglutide and tirzepatide are the two weekly injections patients ask us about most. Both reduce appetite and help you feel full sooner, and both work best alongside healthier eating and regular activity. The differences come down to how they work, how your body tolerates them, and what fits your health history and budget.
How semaglutide works
Semaglutide mimics GLP-1, a hormone your gut releases after you eat. It slows how quickly your stomach empties, signals fullness to the brain, and helps regulate blood sugar. Most patients notice smaller portions feel satisfying and cravings become easier to manage.
How tirzepatide works
Tirzepatide acts on two hormones instead of one: GLP-1 and GIP. GIP also plays a role in appetite and how the body handles sugar and fat. Because it works on both pathways, many patients find it a strong option, especially if they’ve plateaued on other approaches.
Side by side
- How it’s taken: both are once-weekly injections under the skin, started at a low dose and increased gradually.
- Hormones targeted: semaglutide acts on GLP-1; tirzepatide acts on GLP-1 and GIP.
- Common side effects: similar for both, mainly nausea, diarrhea, constipation and reduced appetite, usually during dose increases.
- Track record: semaglutide has been used for weight management longer; tirzepatide is newer.
- Who shouldn’t use either: people with a personal or family history of medullary thyroid cancer or MEN 2, and people who are pregnant.
Which one is better?
There’s no single answer. Research on the brand-name versions suggests tirzepatide tends to produce more weight loss on average, but the right choice depends on you: your medical history, other medications, how you tolerate side effects, your goals and your budget. Some patients start on one and switch to the other later. Results with compounded versions haven’t been studied the same way, which is one reason a physician-supervised plan matters.
How we help you decide
At your consultation, Dr. Joseph reviews your health history and goals, explains both options, and recommends a starting point. We set your dose, check in regularly, and adjust as you go. Learn more about our semaglutide program and tirzepatide program.
Ready to talk it through? Book a consultation at our Van Nuys or Canoga Park office, or call (877) 991-1191. Telehealth visits are available anywhere in California.
This article is for general education and isn’t a substitute for medical advice. Compounded medications are prepared by licensed pharmacies for individual patients. They are not FDA-approved and have not been reviewed by the FDA for safety or effectiveness.
