Semaglutide vs Tirzepatide
Semaglutide and tirzepatide are the two active ingredients behind the four best known weekly GLP-1 injections. Semaglutide is sold as Ozempic and Wegovy; tirzepatide is sold as Mounjaro and Zepbound. This page puts the two ingredients side by side: what each is approved for, how the dosing works, what the trial programs found, and what each one costs. It is education only, not medical advice, and it does not declare a winner, because the suitable choice depends on your diagnosis, your history and your prescriber.
The two ingredients at a glance
| Detail | Semaglutide | Tirzepatide |
|---|---|---|
| Active ingredient | Semaglutide, a GLP-1 receptor agonist | Tirzepatide, which acts on both GIP and GLP-1 receptors |
| Sold as | Ozempic and Wegovy | Mounjaro and Zepbound |
| Approved for | Type 2 diabetes (Ozempic) and weight management (Wegovy) | Type 2 diabetes (Mounjaro), weight management and obstructive sleep apnea (Zepbound) |
| How often | One injection, once a week | One injection, once a week |
| Max weekly dose | 2 mg in Ozempic; the Wegovy maintenance dose is 2.4 mg | 15 mg in both Mounjaro and Zepbound |
| Trial result | In STEP 1, people on the 2.4 mg dose lost an average of 14.9 percent of body weight over 68 weeks | In SURMOUNT-1, people on the 15 mg dose lost an average of 20.9 percent of body weight over 72 weeks |
| About list price per month | About $1,000 for Ozempic and about $1,350 for Wegovy | About $1,080 for Mounjaro and about $1,060 for Zepbound |
Read the trial row with care. STEP 1 and SURMOUNT-1 were separate trials, run in different groups of people over different lengths of time. They were not a head to head comparison, so the two percentages cannot be used to say that one medicine beats the other for any individual person.
How they differ in practice
The clearest difference is how each ingredient works. Semaglutide copies one gut hormone, GLP-1, and acts on its receptors to slow stomach emptying, reduce appetite and help the pancreas release insulin when blood sugar is high. Tirzepatide acts on two hormone receptors, GIP and GLP-1, which is why it is often described as a dual agonist. Both are given as one injection, once a week, and both are started low and stepped up slowly so the body can get used to them.
The dose numbers look very different, and they cannot be compared directly. A milligram of semaglutide is not a milligram of tirzepatide, because they are different molecules with different strengths. Semaglutide schedules start at 0.25 mg once weekly and rise in steps at least four weeks apart; tirzepatide starts at 2.5 mg and rises in 2.5 mg steps. The semaglutide dosage chart and the tirzepatide dosage chart set out both schedules in full.
In day to day use the experience is similar: a weekly pen, the strongest appetite effect in the first days after each dose for many people, and dose increases spaced out over months. Which ingredient a person ends up on usually follows from the diagnosis first and from tolerability, response and coverage after that.
Side effects compared
The two labels list much the same core side effects, led by nausea, vomiting, diarrhea and constipation, along with indigestion, reflux and reduced appetite. These effects are most common while the dose is climbing and often settle as the body adjusts. Response varies a lot from person to person, so the label lists cannot tell you which ingredient you personally would find easier. The semaglutide side effects page and the tirzepatide side effects page go through each profile in plain language, including the serious warnings both labels carry.
Who each is usually prescribed for
Each ingredient has one brand approved for type 2 diabetes and one approved for weight management, and Zepbound adds an approval for obstructive sleep apnea in adults with obesity. In practice, prescribers usually start from the condition being treated and pick the product whose label matches it, because insurance coverage normally follows the label. Within that, they weigh your other conditions, your other medicines, how you responded to any earlier treatment, and what your plan will cover.
Switching between them
People do move from one ingredient to the other, most often because of side effects, a response that has levelled off, supply problems or a change in coverage. Switching is always a prescriber decision, never something to do on your own. The new medicine has its own published schedule, and your prescriber will set where you start on it, how the changeover is timed, and what to watch for in the first weeks. If you are thinking about a switch, bring the reason to your prescriber rather than a preferred product, because the reason usually points to the right answer.
Frequently asked questions
Is tirzepatide stronger than semaglutide?
That is not a claim either label makes. The headline figures, 20.9 percent average weight loss in SURMOUNT-1 and 14.9 percent in STEP 1, come from separate trials with different people and different durations, so they are not a head to head result. Individual response varies widely on both ingredients, and tolerability matters as much as the average, because a medicine only works if you can stay on it.
Can you take semaglutide and tirzepatide together?
No. They are alternatives to each other, not partners. Each label describes a standalone treatment, and combining two medicines from this class is not an approved use. If one ingredient is not working for you, the conversation to have with your prescriber is about switching, not stacking.
Which is cheaper, semaglutide or tirzepatide?
At list price the four brands sit in a similar band, from about $1,000 a month for Ozempic to about $1,350 for Wegovy, with Mounjaro at about $1,080 and Zepbound at about $1,060. What you actually pay depends far more on your insurance coverage and any savings program than on the ingredient.
Do semaglutide and tirzepatide have the same side effects?
The profiles overlap heavily. Both labels list nausea, vomiting, diarrhea and constipation among the most common effects, worst while the dose is climbing. The details and the serious warnings are set out on the semaglutide side effects and tirzepatide side effects pages of this site.
Can I switch from semaglutide to tirzepatide?
Switching is possible, but it is a prescriber decision, never a self switch. Your prescriber will set the starting dose on the new medicine, time the changeover, and tell you what to watch for. Do not overlap the two, and do not carry a dose across from one ingredient to the other, because the milligram numbers are not equivalent.