Ozempic, Wegovy, Mounjaro, Zepbound, Retatrutide and Pills: The New Weight-Loss Drugs Compared (2026)

Medical note: this article explains published trial results, regulator decisions and prices for general information. It is not medical advice. These are prescription medicines with real risks; talk to a doctor before starting, stopping or switching any of them.

Five years ago there was essentially one modern weight-loss injection. In 2026 there are injections, two daily pills, a high-dose version, a triple-action drug in late trials, cheap generics in several countries and a US government price deal. The brand names alone are confusing: Ozempic and Wegovy are the same drug, and so are Mounjaro and Zepbound.

This guide untangles it all. It compares the main drugs side by side, explains how much weight people actually lost in the trials, lists the common and serious side effects, and covers prices, eligibility and what happens when you stop.

Contents

1. The names explained
2. How these drugs work
3. Comparison table
4. Semaglutide: Ozempic, Wegovy, the Wegovy pill and Wegovy HD
5. Tirzepatide: Mounjaro and Zepbound
6. Foundayo (orforglipron): the no-rules pill
7. Coming next: retatrutide, CagriSema and MariTide
8. Benefits beyond weight
9. Side effects and risks
10. What happens when you stop
11. Who qualifies
12. Prices, insurance and generics
13. Compounded and counterfeit versions
14. Diet, protein and exercise
15. FAQ

The names explained

The diabetes and weight-loss versions of the same drug differ mainly in dose and in which uses regulators have approved. "Ozempic" is often used loosely in the media for any of these drugs.

How these drugs work

All of these medicines copy or influence hormones that the gut and pancreas release after eating.

• GLP-1 makes you feel full sooner, slows how quickly the stomach empties and helps the body release insulin. Semaglutide and orforglipron act on GLP-1 only.
• GIP is a second gut hormone that appears to add to GLP-1's effect. Tirzepatide acts on both GIP and GLP-1.
• Glucagon can increase energy use and fat burning in the liver. Retatrutide acts on GIP, GLP-1 and glucagon, which is why it is called a "triple agonist".
• Amylin is a pancreatic hormone that also increases fullness. CagriSema adds an amylin-like drug (cagrilintide) to semaglutide.

In practice, people taking these drugs typically report feeling less hungry and thinking about food less, so they eat less. The doses are increased slowly over weeks or months to limit stomach side effects.

Comparison table

Trial results are reported in two ways. "Treatment-regimen" figures include everyone who was randomised, even those who stopped the drug. "Efficacy" figures count only people who kept taking it, so they are higher. Where a source specifies, we say which.

Trials differ in length, dose and the people enrolled, so comparing numbers across different trials is only a rough guide. The most reliable comparison is a head-to-head trial, described below.

Semaglutide: Ozempic, Wegovy, the Wegovy pill and Wegovy HD

Semaglutide is the drug that started the boom. In the STEP 1 trial (published in the New England Journal of Medicine in 2021), adults with obesity taking 2.4 mg weekly lost about 15% of their body weight over 68 weeks, compared with about 2.4% on placebo.

Novo Nordisk has since widened the range:

• Wegovy pill: approved by the FDA on 22 December 2025 as the first oral GLP-1 for weight management, and launched in the US in January 2026. Novo reported 16.6% weight loss in the OASIS 4 trial among people who kept taking it. The pill must be taken on an empty stomach with a small sip of water, then a short wait before eating.
• Wegovy HD (7.2 mg): a higher weekly dose. In the STEP UP trial, people without diabetes lost 20.7% at 72 weeks (efficacy figure). Its FDA approval was announced in March 2026.

For more on the pill versions, see our earlier article on how weight-loss pills went mainstream.

Tirzepatide: Mounjaro and Zepbound

Tirzepatide, made by Eli Lilly, acts on two hormones (GIP and GLP-1). In SURMOUNT-1 (NEJM, 2022), people on the highest 15 mg dose lost an average of 20.9% of their body weight at 72 weeks.

The clearest comparison came from SURMOUNT-5, a head-to-head trial in 750 adults with obesity published in NEJM in May 2025:

Tirzepatide produced significantly more weight loss. That does not mean it is the right choice for everyone: side effects, price, insurance coverage and other health conditions all matter.

Foundayo (orforglipron): the no-rules pill

Orforglipron is a small-molecule pill rather than a peptide, which is why it can be taken at any time of day, with or without food and water. The FDA approved it as Foundayo on 1 April 2026 for adults with obesity, or overweight plus a weight-related condition, after a fast review under a priority voucher.

In the ATTAIN-1 trial, people on the top dose lost 12.4% of their body weight at 72 weeks among those who kept taking it (11.1% counting everyone randomised). That is less than the injections, but some people strongly prefer a pill that needs no injection and no fasting. In Europe, the EMA's committee recommended approval in October 2026, with a European Commission decision expected around December.

Coming next: retatrutide, CagriSema and MariTide

Retatrutide (Eli Lilly)

Retatrutide is the drug that has generated the most excitement. It acts on three hormones. In the TRIUMPH-1 trial of 2,339 adults without diabetes, announced in May 2026, average weight loss at 80 weeks was 19.0% on 4 mg, 25.9% on 9 mg and 28.3% on 12 mg, against 2.2% on placebo. Side effects were also more frequent: nausea affected up to 42% of participants, and 11.3% on the top dose stopped because of side effects, compared with 4.9% on placebo.

Lilly plans to file for FDA approval in the first quarter of 2027. Until then, retatrutide is not licensed anywhere, and anything sold as "retatrutide" online is unapproved. Read our full report on the retatrutide trial results.

CagriSema (Novo Nordisk)

CagriSema combines semaglutide with cagrilintide. In REDEFINE 1 it produced 22.7% weight loss at 68 weeks, versus 16.1% for semaglutide alone. However, in REDEFINE 4, a head-to-head trial against tirzepatide over 84 weeks, CagriSema reached 23.0% versus 25.5% for tirzepatide and missed its goal. Novo submitted it to the FDA in December 2025 and expects a decision in late 2026.

MariTide (Amgen)

MariTide is designed to be injected monthly or less often. In a Phase 2 trial announced in November 2024, it produced up to about 20% weight loss at 52 weeks. Phase 3 trials are under way.

Benefits beyond weight

Regulators have approved some of these drugs for conditions other than weight loss, based on large outcome trials:

• Heart: in the SELECT trial (NEJM, 2023), Wegovy reduced major cardiovascular events (heart attack, stroke or cardiovascular death) by 20% in people with heart disease and overweight or obesity but no diabetes. The FDA added this use in March 2024.
• Sleep apnoea: the FDA approved Zepbound for moderate-to-severe obstructive sleep apnoea in adults with obesity in December 2024.
• Kidneys: based on the FLOW trial, Ozempic was approved in the US in January 2025 to reduce the risk of kidney disease worsening in people with type 2 diabetes and chronic kidney disease.
• Liver: on 15 August 2025, Wegovy received FDA accelerated approval for MASH (a form of fatty liver disease) with moderate-to-advanced liver scarring but no cirrhosis.

Side effects and risks

Stomach and gut side effects

The most common side effects are digestive, and they are usually worst while the dose is being increased. From the US prescribing information and Lilly's trial data:

These figures come from separate trials with different designs, so they should not be read as a direct head-to-head comparison. In the Wegovy trials, 4.3% of people stopped because of gut side effects, versus 0.7% on placebo.

Less common but serious risks

• Pancreatitis: inflammation of the pancreas was rare but more common than on placebo. Severe stomach pain that spreads to the back needs urgent medical attention.
• Gallbladder problems: gallstones occurred in 1.6% of people on Wegovy versus 0.7% on placebo.
• Thyroid tumours (boxed warning): semaglutide and tirzepatide caused thyroid C-cell tumours in rodents. It is not known whether this happens in humans, but people with a personal or family history of medullary thyroid cancer or MEN 2 must not use them.
• NAION (a rare eye condition): in June 2025 the European Medicines Agency concluded that NAION, a type of optic nerve damage that can cause sudden vision loss, is a very rare side effect of semaglutide, affecting up to 1 in 10,000 users. Anyone with sudden vision loss should contact a doctor immediately.
• Surgery and anaesthesia: because these drugs slow stomach emptying, tell your surgical team you take one. A 2024 multi-society guidance says most patients can continue them before elective surgery, but some may need a liquid diet the day before.
• Pregnancy: the UK regulator, the MHRA, says these drugs should not be used in pregnancy or while breastfeeding. It advises stopping semaglutide at least two months, and tirzepatide at least one month, before trying to conceive. Tirzepatide may also make oral contraceptive pills less effective, particularly after starting and after dose increases.

Mood and suicidal thoughts

Earlier labels told doctors to monitor for depression and suicidal thoughts. In April 2024 the EMA's safety committee found the evidence did not support a causal link, and on 13 January 2026 the FDA asked manufacturers to remove the suicidal-thoughts warning from Wegovy, Zepbound and Saxenda labels after large analyses found no increased risk. Anyone who notices changes in mood should still speak to their doctor.

Muscle and lean mass

Not all the weight lost is fat. Body-scan sub-studies suggest a substantial share of the weight lost on these drugs is lean mass, which includes muscle but also water and other tissue. This is one reason doctors recommend adequate protein and strength training alongside treatment.

What happens when you stop

These drugs treat a long-term condition; they do not cure it. Two trials show what happens when people stop:

• STEP 1 extension (semaglutide): people lost 17.3% of their body weight by week 68. A year after stopping, they had regained about two-thirds of it, ending 5.6% below their starting weight. Most improvements in blood pressure and blood sugar also faded.
• SURMOUNT-4 (tirzepatide): after 36 weeks on tirzepatide, people who switched to placebo regained 14.0% of their body weight, while those who stayed on the drug lost a further 5.5%. At week 88, the overall change was −25.3% for those who stayed on it versus −9.9% for those who stopped.

The practical lesson: plan for long-term use, or work with a doctor on a structured way to reduce the dose with strong diet and activity support.

Who qualifies

In England, the NHS is rolling out Mounjaro gradually. In the first year it targeted people with a BMI of 40 or more and at least four of five listed conditions, with about 220,000 people expected to be treated over three years. A BMJ analysis found wide variation between local health areas, a "postcode lottery".

Prices, insurance and generics

United States

List prices before insurance are high: Wegovy is listed at about $1,349 per package. In practice, many people now pay cash through the makers' own programmes, which have cut prices sharply since 2025. Prices checked in October 2026:

Under a deal announced by the White House on 6 November 2025, Novo Nordisk and Lilly agreed lower prices through the TrumpRx website and for Medicare and Medicaid. Since 1 July 2026, a temporary Medicare GLP-1 Bridge lets eligible Part D enrollees get covered weight-loss drugs for a $50 monthly copay, with prior authorisation, according to NPR. It is scheduled to run until the end of 2027.

Employer coverage, by contrast, is shrinking. A Business Group on Health survey reported in September 2026 found about 60% of large employers covered GLP-1s for weight loss, down from 72% in 2025.

Generics outside the US

The main semaglutide patent has expired in several countries, and cheaper generic versions have arrived:

• India: generics launched on 21 March 2026 from several drugmakers, including Dr Reddy's, Zydus, Sun Pharma and Glenmark, at a fraction of the branded price.
• Canada: Health Canada approved its first generic semaglutide in April 2026 and the first generic for weight loss on 29 June 2026.
• Brazil: the regulator Anvisa registered a first generic semaglutide for diabetes in May 2026.
• China: Novo says data protection runs until 2027, so generics are expected then.
• US and EU: semaglutide remains protected until the early 2030s.

Compounded and counterfeit versions

During the 2022–2024 shortages, US pharmacies were allowed to make "compounded" copies of semaglutide and tirzepatide. The FDA declared the shortages over (tirzepatide in December 2024, semaglutide in February 2025), and the grace periods for compounders ended in spring 2025. In September 2025 the FDA sent more than 50 warning letters to telehealth companies and clinics over misleading claims about compounded versions. In February 2026, Hims & Hers withdrew a $49 compounded copy of the Wegovy pill within days of launching it, after the FDA and HHS announced action.

Counterfeits are a separate and more dangerous problem. The WHO issued an alert in 2024 about falsified semaglutide found in several countries. The UK's MHRA has reported fake pens containing insulin, which caused hospital admissions, and in late 2025 said organised crime groups were producing professionally branded fakes, including pens labelled as the unapproved drug retatrutide.

How to protect yourself:

• Only get these medicines with a prescription from a licensed prescriber and a registered pharmacy.
• Avoid social media sellers, beauty salons and websites offering them without a prescription.
• Be very wary of anything sold as retatrutide: it is not approved anywhere.
• Check packaging, and report suspected fakes to your national regulator.

Diet, protein and exercise

A joint advisory published in May 2025 by four US obesity and nutrition societies set out priorities for people taking these drugs. They include a nutritional assessment before starting, managing gut side effects, eating nutrient-dense and minimally processed food, preventing vitamin and mineral deficiencies, getting enough protein and doing strength training to preserve lean mass, and paying attention to sleep and stress. The WHO and NICE both recommend the drugs alongside diet and activity support, and the NHS makes this "wraparound" support mandatory.

Because people eat less on these drugs, the quality of what they eat matters more. Our Vitamins and Minerals Explained series covers the nutrients most worth watching.

FAQ

Are Ozempic and Wegovy the same drug?

Yes. Both contain semaglutide. Ozempic is approved for type 2 diabetes (and some heart and kidney uses), while Wegovy is approved for weight management, at a higher maximum dose.

Which drug causes the most weight loss?

Among approved drugs, tirzepatide (Zepbound/Mounjaro) beat semaglutide in the head-to-head SURMOUNT-5 trial: 20.2% versus 13.7% at 72 weeks. Retatrutide has shown more in trials (28.3% at 80 weeks on the top dose) but is not approved.

Are the pills as good as the injections?

In trials the pills produced somewhat less weight loss than the strongest injections: 16.6% for the Wegovy pill (among people who kept taking it) and 12.4% for Foundayo on the top trial dose. Many people prefer them because they avoid injections.

Will I regain weight if I stop?

Most people do. In trials, people regained about two-thirds of the weight lost within a year of stopping semaglutide, and a large share after stopping tirzepatide.

When will retatrutide be available?

Eli Lilly plans to file with the FDA in the first quarter of 2027. Approval would come after that, so it is unlikely to be on pharmacy shelves before late 2027 at the earliest.

Is it safe to buy these drugs online?

Only from a licensed pharmacy with a valid prescription. Regulators have repeatedly warned about fake and contaminated products sold online and on social media.

Do these drugs cause muscle loss?

Part of the weight lost is lean mass, which includes muscle. Eating enough protein and doing resistance exercise can help protect it.

Information checked in October 2026. Prices, approvals and coverage change frequently. This article is for general information and is not a substitute for advice from a doctor or pharmacist.

Sources

• NEJM: Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5), via TCTMD
• Novo Nordisk: Wegovy pill approved in the US
• Healio: FDA approves high-dose Wegovy 7.2 mg
• Eli Lilly: FDA approves Foundayo (orforglipron)
• HCPLive: Retatrutide meets weight-loss endpoints in phase 3 obesity trial
• Drugs.com: CagriSema FDA approval status
• FDA: Wegovy prescribing information
• Lilly Medical: Gastrointestinal adverse events in Zepbound studies
• EMA: PRAC concludes NAION is a very rare side effect of semaglutide
• HCPLive: FDA requests removal of suicidal ideation warning from GLP-1 therapies
• Pharmaceutical Journal: MHRA urges contraception for people on weight-loss drugs
• Wilding et al.: Weight regain after withdrawal of semaglutide (STEP 1 extension)
• JAMA: SURMOUNT-4 randomized clinical trial
• NHS England: Interim commissioning guidance for tirzepatide (NICE TA1026)
• WHO: Global guideline on GLP-1 medicines for obesity
• NovoCare: Price your Wegovy
• NPR: Medicare beneficiaries can get obesity drugs for $50 a month
• Health Canada: Canada approves first generic semaglutide for weight loss
• HT World: Crime gangs making fake branded weight-loss jabs, MHRA warns
• Obesity Medicine Association: Nutritional priorities to support GLP-1 therapy