Is Zepbound the Same as Tirzepatide? Brand, Molecule, and What Actually Differs

Yes — Zepbound is tirzepatide. Tirzepatide is the drug; Zepbound is one of two brand names Eli Lilly sells it under. The other is Mounjaro. Same molecule, same manufacturer, two names, and the difference between them is not chemistry.

The molecule is identical, and both labels say so in the same words

Both labels describe their product with the same phrase, word for word: "a glucose-dependent insulinotropic polypeptide (GIP) receptor and glucagon-like peptide-1 (GLP-1) receptor agonist"¹². That dual action is what makes tirzepatide different from semaglutide, which acts at the GLP-1 receptor only.

So there is no "Zepbound molecule" and no "Mounjaro molecule." There is tirzepatide, sold twice.

What differs is the approved indication — and the approved age

This is where the two brands genuinely part company, and it is more than a marketing split.

Mounjaro is indicated "as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus"¹.

Zepbound is indicated, alongside a reduced-calorie diet and increased physical activity, "to reduce excess body weight and maintain weight reduction long term in adults with obesity or adults with overweight in the presence of at least one weight-related comorbid condition," and separately "to treat moderate to severe obstructive sleep apnea (OSA) in adults with obesity"².

Three real differences fall out of those two sentences:

1. 1.Different conditions. Diabetes for one, weight and obstructive sleep apnea for the other.
2. 2.Different ages. Mounjaro's label reaches pediatric patients aged 10 and older. Zepbound's says adults, in both of its indications.
3. 3.Zepbound carries a sleep-apnea indication that Mounjaro does not. That is not a weight claim wearing a different hat — it is a separate approved use.

Why the same drug got two names

Because indications are approved per application, not per molecule. The obesity indication rested on its own trial program: SURMOUNT-1 enrolled adults with a BMI of 30 or more, or 27 or more with at least one weight-related complication, and specifically excluded people with diabetes³. That is a different population from the diabetes trials that supported Mounjaro, so it is a different label — and, commercially, a different brand, a different price and different insurance handling.

The dosing, meanwhile, is recognizably the same drug. Mounjaro starts at 2.5 mg once weekly, increases to 5 mg after 4 weeks, then rises in 2.5 mg increments after at least 4 weeks on the current dose, to an adult maximum of 15 mg weekly¹.

The two questions people are usually really asking

"Is Zepbound a semaglutide?" No. Semaglutide is the molecule in Ozempic, Wegovy and Rybelsus, and it is a GLP-1 receptor agonist. Zepbound is tirzepatide, which acts at both the GIP and GLP-1 receptors². Different molecules, different manufacturers, overlapping purposes. Our tirzepatide versus semaglutide article covers the head-to-head trial data.

"Is compounded tirzepatide the same as Zepbound?" No, and this is the distinction that costs people the most. Compounded tirzepatide is not Zepbound and is not an FDA-approved product; it does not carry either label quoted here, and neither label's dosing schedule, strengths or safety information automatically applies to it. Our compounded tirzepatide explainer covers what compounding does and does not guarantee, and our article on whether compounded tirzepatide is still legal covers the regulatory position after the shortage ended.

What to take from this

Zepbound is tirzepatide. So is Mounjaro. The molecule does not change between them; the approved condition, the approved age range and the sleep-apnea indication do. If someone hands you dosing or safety information for one brand and you are taking the other, the underlying pharmacology transfers but the label does not — and if you are taking a compounded version, neither label was written about what is in your vial. For what a specific dose in a compounded vial actually amounts to, our units-versus-milligrams explainer covers why the number on the syringe is not the number on a label, and our tirzepatide provider comparison shows what each provider publishes for the version it actually sells.