Mounjaro vs Zepbound: what’s the difference?

Mounjaro and Zepbound are the same medicine, tirzepatide, made by Eli Lilly in the same six strengths. When the FDA approved Zepbound on November 8, 2023, it noted that tirzepatide was already approved as Mounjaro for type 2 diabetes. The difference is the label: Mounjaro is approved to treat type 2 diabetes, and Zepbound is approved for weight reduction and obstructive sleep apnea. That label decides how each is dosed, who pays for it and what it costs.

Here is how the two compare, with self-pay prices read from LillyDirect on October 26, 2026.

Mounjaro and Zepbound at a glance

Sources: the Mounjaro and Zepbound labels, LillyDirect’s Mounjaro and Zepbound pages, and the CMS Bridge form.

Same drug, two approvals

Lilly tested tirzepatide twice: in people with type 2 diabetes, measuring blood sugar (the SURPASS trials, behind Mounjaro), and in people with obesity or overweight, measuring weight (the SURMOUNT trials, behind Zepbound). The FDA approved each product for what its trials showed.

• Mounjaro, first approved in 2022, is approved to improve blood sugar in adults and children 10 and older with type 2 diabetes. Since August 2026, its label also covers lowering the risk of heart attack, stroke and cardiovascular death in adults with type 2 diabetes who are at high risk.
• Zepbound is approved for long-term weight reduction in adults with obesity, or with overweight and a weight-related condition such as high blood pressure or type 2 diabetes. It added moderate to severe obstructive sleep apnea in adults with obesity on December 20, 2024.

Mounjaro has no weight-management indication, so prescribing it for weight loss alone is off-label. Zepbound’s approval, on the other hand, includes adults with type 2 diabetes who need to lose weight. You can’t take the two together: the FDA said Zepbound “should not be used in combination with Mounjaro or a GLP-1 receptor agonist.”

Doses and devices

The strengths match, but the dose plans don’t. Mounjaro starts at 2.5 mg a week, and the label allows 2.5 mg increases after at least 4 weeks on a dose if blood sugar needs more control, up to 15 mg in adults and 10 mg in children. There’s no set maintenance dose; it depends on blood sugar.

Zepbound starts at 2.5 mg for 4 weeks, then rises in 2.5 mg steps at least 4 weeks apart to a maintenance dose of 5, 10 or 15 mg for weight, or 10 or 15 mg for sleep apnea. The 2.5 mg dose is for starting only.

Both labels list single-dose pens and vials, plus a KwikPen and multi-dose vial that hold four weekly doses. What you can buy self-pay differs: LillyDirect sells Mounjaro as single-dose pens, and Zepbound as single-dose vials or KwikPens (the single-dose Zepbound pen there is for insurance fills). Our Zepbound vials vs KwikPen guide compares the devices.

What the trials showed

Mounjaro’s diabetes trials and Zepbound’s weight trials measured different things in different people. These figures are from each label.

Scroll sideways to see the full table

Two points stand out. People with type 2 diabetes lost less weight on the same drug than people without it, 14.7% against 20.9% at 15 mg. And in SURPASS-2, which Lilly funded, every tirzepatide dose lowered blood sugar and weight more than semaglutide 1 mg, an Ozempic dose. Our Zepbound vs Ozempic guide covers that comparison, and our semaglutide vs tirzepatide guide has the weight-loss head-to-head.

Side effects

Stomach side effects are the most common on both, mostly while the dose is rising. The rates below come from each label’s placebo-controlled trials, which enrolled different people, so compare each with its own placebo.

Scroll sideways to see the full table

In Zepbound’s weight trials, 4.8% to 6.7% of people stopped because of side effects, against 3.4% on placebo. Both labels carry a boxed warning for thyroid C-cell tumors, and neither drug is for anyone with a personal or family history of medullary thyroid carcinoma or MEN 2. Both also warn about pancreatitis, gallbladder disease, low blood sugar with insulin or sulfonylureas, kidney injury from dehydration and severe stomach problems. See our Zepbound side effects guide and GLP-1 side effects guide.

What each costs in October 2026

These are LillyDirect’s self-pay prices for one month, read on October 26, 2026.

At the 5 mg dose, Zepbound costs $100 a month less, and at 7.5 mg and up $50 less as long as you refill on time. Late Zepbound refills at 10 mg and up cost $200 more than Mounjaro.

With commercial insurance that covers the single-dose pen, Lilly’s savings cards can bring Mounjaro or Zepbound to as little as $25 a fill. Savings are capped at $150 a month and $1,950 a year for Mounjaro, and $100 a month and $1,300 a year for Zepbound. Both cards require a prescription “for an approved use consistent with FDA-approved product labeling,” so the Mounjaro card is built for type 2 diabetes. Our Zepbound cost guide, tirzepatide cost guide and Zepbound coupon guide go further, and our Zepbound rankings compare programs that prescribe it.

Insurance and Medicare

Coverage follows the approved use. A commercial plan that covers diabetes drugs may cover Mounjaro for type 2 diabetes and still exclude weight-loss drugs, so ask your plan about the reason you’re being prescribed. Our insurance guide lists the questions to ask.

Medicare puts this in writing on its GLP-1 Bridge form. Type 2 diabetes and sleep apnea prescriptions go to your regular Part D plan. A prescription to reduce body weight goes through the Medicare GLP-1 Bridge, at $50 a month from July 1, 2026 to December 31, 2027, and the Bridge lists the Zepbound KwikPen, not Mounjaro or the other Zepbound forms. See does Medicare cover Wegovy or Zepbound.

Which one fits you

• If weight loss is the goal, Zepbound is the tirzepatide product approved for it, with or without type 2 diabetes.
• If you have type 2 diabetes and blood sugar is the main goal, your clinician may prescribe Mounjaro, which is also approved to lower heart risk.
• If you have obstructive sleep apnea and obesity, Zepbound is the one approved for it.
• If you’re paying cash, Zepbound costs less at every dose with on-time refills.
• If you’re a child or teen with type 2 diabetes, Mounjaro is approved from age 10; Zepbound is for adults.

A licensed clinician can weigh these with your history, other medicines and coverage. Our match tool finds programs that prescribe Zepbound.

The bottom line

Mounjaro and Zepbound are both tirzepatide at the same strengths. Mounjaro is approved for type 2 diabetes and Zepbound for weight reduction and sleep apnea, so the reason you’re prescribed decides which one you get and how insurance pays. As of October 2026, Zepbound costs $299 to $449 a month self-pay at LillyDirect with on-time refills, against $499 for Mounjaro. Never take both. More options on our weight-loss hub.