Retatrutide Questions Answered: Mounjaro, Ozempic, Price and Approval

Retatrutide is Eli Lilly's experimental once-weekly injection for obesity. It acts on three hormone receptors (GIP, GLP-1 and glucagon), where tirzepatide (Mounjaro, Zepbound) acts on two and semaglutide (Ozempic, Wegovy) on one. Its trials have reported larger average weight loss than either, but no head-to-head trial has reported results. As of 22 October 2026 it is not FDA-approved, Lilly plans to apply in the first quarter of 2027, and no price has been announced.¹²³⁴⁵

Below are straight answers to the questions people ask most, taken from trial records, FDA labels and Lilly's own statements. The last section explains the one question we deliberately leave unanswered: amounts and mixing steps for retatrutide bought online. None of this is medical advice.

Retatrutide, Mounjaro and Ozempic side by side

All figures were checked on 22 October 2026. The weight-loss results come from different trials with different lengths and participants, so they cannot be ranked against each other; our guide to the next weight-loss drugs explains why.

Sources:^{145678910111213141516}. Ozempic and Mounjaro approval years are from their labels.

Ozempic and Wegovy are the same medicine with different approved uses, as are Mounjaro and Zepbound. Of the semaglutide brands, only Wegovy is approved for weight management.¹²¹³

What's the difference between retatrutide and Mounjaro?

Both are weekly Lilly injections. Tirzepatide, the medicine in Mounjaro and Zepbound, acts on the GIP and GLP-1 receptors; retatrutide adds the glucagon receptor. In Lilly's laboratory and mouse studies, the glucagon activity added higher energy use to the reduced food intake driven by the other two.¹⁶ Those are animal findings. Human trials test the whole molecule, so they cannot show what each receptor contributes. Our guide to multi-receptor agonists explains the biology.

The bigger practical difference is status. Tirzepatide has been approved since 2022; retatrutide has trial data only. The direct comparison is TRIUMPH-5, a double-blind trial of about 800 adults with obesity that measures weight change at 80 weeks. As of 22 October 2026 it was no longer recruiting, with main results expected around November 2026.⁴ Until then, see our retatrutide vs tirzepatide comparison and our guide to retatrutide side effects, which covers findings such as a rise in heart rate.⁸

If you already take Mounjaro, Zepbound, Ozempic or Wegovy, there is no evidence yet that switching would help you, and an online product adds risks of its own. Discuss any change with your prescriber.

Is retatrutide stronger than Ozempic?

On paper the numbers are bigger. In STEP 1, semaglutide groups lost 14.9% of body weight over 68 weeks; in TRIUMPH-1, the highest retatrutide dose gave 25.0% over 80 weeks.¹⁶ But these were different trials, run years apart with different people. FDA labels warn that adverse reaction rates in one drug's trials "cannot be directly compared to rates in the clinical trials of another drug", and the same caution applies to weight results.¹⁰

Only a head-to-head trial can settle it. When tirzepatide was compared directly with semaglutide in SURMOUNT-5, an open-label trial funded by Lilly, tirzepatide groups lost 20.2% against 13.7% over 72 weeks.⁹ No such result exists for retatrutide. TRANSCEND-T2D-2 compares it with semaglutide in about 1,250 adults with type 2 diabetes, but its main measure is blood sugar (HbA1c), not weight. Data collection for that measure finished in August 2026; no results had been posted or announced by 22 October.⁵ Our retatrutide vs semaglutide page tracks it.

Stronger is also not the same as better. In the phase 2 trial, gastrointestinal side effects rose with dose.⁸ And retatrutide's heart and kidney outcomes trial is not expected to finish its main phase until 2029, so whether it reduces heart attacks and strokes is unknown.³⁰

When will retatrutide be approved?

Not yet: Lilly has not applied for approval. On 5 August 2026 Lilly said its clinical data package "is now complete to support global registrations", "with plans to submit a Biologics License Application to the U.S. FDA in the first quarter of 2027."² That is the position as of 22 October 2026. Lilly reports third-quarter results on 29 October 2026, and plans can change.¹⁸

Applying is not approval. FDA aims to act on 90% of standard applications for new medicines "within 10 months of the 60-day filing date", roughly a year after submission, or six months under priority review.¹⁷ It could approve, ask for more data, or refuse. Our explainer on how regulatory approval works covers the steps.

Until then, retatrutide is legally available in the US only in clinical trials or, for a small group of adults with severe obesity and serious complications who cannot join a trial, through Lilly's expanded access programme, which a doctor must apply for.²⁰ Our guide on joining a weight-loss drug trial explains the trial route.

How much will retatrutide cost?

Nobody outside Lilly knows. As of 22 October 2026 Lilly had announced no price. Figures you see online are guesses, or the prices of unapproved products.

The closest reference point is Lilly's current drug. On 22 October 2026 the Zepbound website listed self-pay prices from $299 a month for the starting dose and as low as $449 for higher doses with on-time refills, with a regular price of up to $699. Insured patients may pay less, and Lilly says offers can change at any time.¹⁵ Lilly also reported that the US prices it actually receives for Zepbound and Mounjaro fell in the second quarter of 2026.² Neither fact predicts what retatrutide will cost.

Does retatrutide stop working after a few months?

What people usually notice is a plateau, not the drug failing. On these medicines weight falls fastest in the early months, then slows and levels off. A Lilly-funded analysis of tirzepatide trials put it plainly: "The rate of weight reduction during obesity treatment declines over time and eventually reaches a weight plateau." The median time to plateau was about 24 to 36 weeks.¹⁹

Retatrutide looks similar. In the phase 2 trial the highest-dose group had lost 17.5% by 24 weeks and 24.2% by 48 weeks, so weight kept falling, but more slowly.⁸ A plateau means the body has found a new balance while the drug is still acting.

Stopping is different. In SURMOUNT-4, people switched from tirzepatide to placebo regained 14.0% of body weight over a year, while those who continued lost a further 5.5%.²¹ There are no equivalent data for retatrutide yet; its maintenance trial, TRIUMPH-6, is due to report in 2028.²² See our guides to what is normal when weight loss stalls and to stopping semaglutide or tirzepatide.

Can retatrutide affect your period or birth control?

The pill. Retatrutide's effect is not publicly known. Lilly studied it with a combined pill in 46 postmenopausal women, finishing in July 2024, but had posted no results by 22 October 2026.²³ Its phase 2 trial excluded women who could become pregnant and were not using adequate contraception.²⁴

The approved drugs give the best guide to the question. Tirzepatide slows stomach emptying, which can reduce absorption of oral contraceptives. The Zepbound label says to "Advise patients using oral hormonal contraceptives to switch to a non-oral contraceptive method, or add a barrier method of contraception for 4 weeks after initiation with ZEPBOUND and for 4 weeks after each dose escalation." It notes the delay "is largest after the first dose and diminishes over time" and that non-oral hormonal methods "should not be affected". Mounjaro's label says the same, and the UK regulator gives matching advice.¹⁰¹¹²⁶ The Wegovy label reports no clinically significant change in the pill's hormones with semaglutide.¹²

Periods. Evidence is thin. A 2026 analysis of reports to FDA's adverse event database found more reports than expected of heavy or in-between bleeding and other menstrual changes with semaglutide, and of in-between bleeding and clots with tirzepatide.²⁵ Voluntary reports cannot show cause or frequency. A 2026 review of randomised trials in women with polycystic ovary syndrome found the evidence "insufficient to draw conclusion" on menstrual regularity.³² We found no published data on retatrutide and periods.

Pregnancy. The Wegovy and Ozempic labels advise stopping semaglutide at least 2 months before a planned pregnancy. The Zepbound label says "Weight loss offers no benefit to a pregnant patient and may cause fetal harm" and advises stopping when pregnancy is recognised, and the UK regulator advises stopping tirzepatide at least 1 month before trying to conceive.^10121326 If you might become pregnant, talk to your prescriber or pharmacist rather than changing contraception or medicine on your own.

Why we don't give a retatrutide dose plan or mixing steps

We understand why people ask. But outside a trial there is no safe answer to give, for four reasons.

There is no approved label. Approved medicines come with tested instructions that a prescriber adapts. Retatrutide has none; FDA says it has "not been found safe and effective for any condition" and "cannot be used in compounding under federal law."³ Our guide on why there is no standard dose for unapproved peptides explains how doses are established.

Trial doses came with supervision. Investigators gave Lilly's own product on a fixed protocol and monitored participants. To limit nausea, doses were raised gradually from a lower starting point on a timetable set by the study, and the phase 2 trial found that starting lower partly reduced gastrointestinal side effects.¹⁸

Online products are not the same drug. In US health records, people using non-trial "retatrutide" lost 7.2% of body weight at 6 to 12 months, against 15.5% for trial volunteers, in a preprint not yet peer-reviewed.²⁷ Of three Australian products tested, one held "only half as much as stated on the label" and two held more; another product sold as retatrutide contained semaglutide instead.²⁸ Our report on gray-market retatrutide has the details.

Home preparation causes errors. FDA has received reports of people drawing up "five to 20 times more than the intended dose" from multiple-dose vials of compounded semaglutide, amid confusion between millilitres, milligrams and "units"; some needed hospital care. FDA also warns that multiple-dose vials carry a higher contamination risk once in use for more than 28 days.³²⁹

What we can suggest instead: consider a trial, ask a doctor about approved options such as Zepbound or Wegovy, or ask about expanded access if you have severe obesity with serious complications.²⁰ Products labelled "research use only" are not approved for use in people.³ If you have already used an online product, our guide on whether online peptides are safe to inject covers what testing has found. Seek urgent care for severe stomach pain that will not go away, sometimes spreading to the back, with or without vomiting, which labels list as a possible sign of pancreatitis, or for vomiting you cannot stop.¹⁰ Report problems to FDA MedWatch or your national regulator.³¹