Cagrilintide is a lab-made copy of amylin, a hormone your pancreas releases alongside insulin every time you eat. Amylin is one of the signals that tells your brain the meal is finished. Cagrilintide is a version of it engineered to last about a week instead of a few minutes.

You cannot get it. There is no FDA-approved cagrilintide product, and Promise does not offer it. The reason the name keeps coming up is CagriSema — cagrilintide and semaglutide together in one weekly injection, which Novo Nordisk has filed with the FDA and which is still under review.

How cagrilintide works, and why amylin is not a GLP-1

Your body has more than one way of saying "enough". GLP-1 is one of those signals, and it is the one semaglutide and tirzepatide imitate. Amylin is a different one.

Amylin comes out of the same pancreatic cells as insulin. It slows how quickly the stomach empties, damps down glucagon — the hormone that pushes blood sugar up — and works in the brainstem to bring a meal to an end. A 2026 review in Diabetes, Obesity and Metabolism walks through that physiology and the handful of amylin drugs now in human trials.

The two signals really do travel different routes. In a June 2026 study in Nature Metabolism, researchers mapped more than 530,000 cells in the brainstem of rats, mice and macaques and traced cagrilintide's longer-term effect to one small group of them. Turning that group down blocked what cagrilintide did to food intake in rats — and left semaglutide's effect untouched. Two different doors into the same room.

One amylin drug has reached the US market before. Pramlintide, sold as Symlin, arrived in 2005 as an add-on to insulin rather than as a weight-loss drug, had to be injected immediately before each major meal, and the FDA's own drug database now lists all three of its presentations as discontinued. Cagrilintide is the attempt to do that job once a week.

What CagriSema did in its own trials

The trial people quote is REDEFINE 1, published in the New England Journal of Medicine in August 2025. It ran 68 weeks in 3,417 adults who had obesity, or overweight plus a related condition, and who did not have type 2 diabetes.

Average weight change was 20.4% down on CagriSema against 3.0% down on placebo. Gut symptoms were common: about four in five people on the combination — 79.6% — reported nausea, vomiting, diarrhoea, constipation or stomach pain, against about two in five on placebo, 39.9%. Most were mild or moderate and eased with time.

A meta-analysis published on 17 August 2026 pooled seven trials and 8,069 people. It put CagriSema ahead of semaglutide alone by roughly 7.6 kg, and ahead of cagrilintide alone by roughly 9.2 kg. Neither half is carrying the result on its own.

Half of that pair is a molecule a provider can already prescribe. Through Promise, semaglutide is dispensed as a compounded medication, which is different from an FDA-approved product: the formulation offered here is not FDA-approved. If you want the detail on how that preparation differs from the branded pens, compounded semaglutide covers it.

How CagriSema did against tirzepatide

This is the part that made headlines in February, and it is worth reading slowly.

Novo Nordisk ran REDEFINE 4, an 84-week open-label trial in 809 adults with obesity, comparing CagriSema against tirzepatide 15 mg. Both are once-weekly injections. In the company's headline results, announced on 23 February 2026, people who stayed on treatment lost 23.0% of their body weight on CagriSema and 25.5% on tirzepatide. Counting everyone regardless of whether they kept taking it, the figures were 20.2% and 23.6%.

The trial's goal was non-inferiority: showing CagriSema was not meaningfully worse than tirzepatide. It did not reach that goal.

That sentence gets over-read constantly, so here is what it is not. It does not mean the drug did nothing — 23% of body weight is a lot. It means that in this one trial, against the current leader, it did not clear the bar the company had set for itself.

A wider view landed a few days ago. On 1 September 2026, Annals of Internal Medicine published an updated systematic review of 38 trials and 25,816 people. Placebo-subtracted weight loss reached 14.8% for semaglutide given under the skin and 19.0% for tirzepatide, and the head-to-head evidence put both tirzepatide and CagriSema ahead of semaglutide on its own. If you are weighing the two you can actually be prescribed today, tirzepatide vs semaglutide sets them side by side.

Where cagrilintide stands with the FDA right now

As of September 6, 2026, the day this article was written, there is no FDA-approved cagrilintide product — not on its own and not in a combination. Novo Nordisk filed CagriSema for weight management in December 2025 on the strength of REDEFINE 1 and REDEFINE 2, said in February that a decision was anticipated by late 2026, and in its half-year report dated 4 August 2026 listed a US decision among its fourth-quarter milestones.

That same report said the lower-dose REDEFINE 9 trial had finished, with the 1.0 mg and 1.7 mg versions beating placebo on weight, and detailed results due at a scientific meeting later this year.

Where a molecule sits with regulators is a fact about the molecule, not a verdict on you. For the compounds Promise does dispense, a licensed provider may still prescribe a compounded formulation of an approved molecule, and that decision is between you and your doctor.

Cagrilintide sold online is not the trial drug

Search the name and you will find vials for sale without a prescription, often blended with something else and sold with a label saying they are meant for laboratory work.

On 31 March 2026 the FDA wrote to PekCura Labs, a Florida seller, about products on its website — among them a page describing a cagrilintide-and-tirzepatide blend. The agency called them unapproved new drugs sold over the internet and said the site's own laboratory-use wording did not change what the products were plainly meant for. Injectables, the letter pointed out, go straight past the body's defences against contamination.

There is no prescriber, no pharmacy of record, and nobody to reach you if a batch turns out to be wrong. Can you buy peptides over the counter goes through what that actually means in practice.

What Promise dispenses works the other way round: you complete the intake for one specific compound, a licensed provider reads your history and decides, and not everyone qualifies.

What to watch next

Three dates are worth holding on to. A US decision on CagriSema is expected in the fourth quarter of 2026. REDEFINE 11, testing the same doses over 80 weeks, reads out in the first half of 2027. And a higher-dose version — cagrilintide 2.4 mg with semaglutide 7.2 mg — started phase 3 in the second half of 2026, with results expected in the first half of 2028.

If cagrilintide caught your eye because you want whatever is furthest ahead, the honest answer is that the newest thing is usually the one nobody can prescribe yet. Retatrutide is in the same position. What a provider can weigh with you today is what already exists.