Retatrutide is the furthest from market of the three compounds covered here: it has no regulatory approval anywhere in the world, in any country, for any use. Everything about it — including anything sold under that name online — is investigational.

How it works

Retatrutide (developed by Eli Lilly under the code LY3437943) activates three receptors at once: GIP, GLP-1, and the glucagon receptor. The added glucagon-receptor activity is the mechanistic difference from tirzepatide — it's theorized to increase energy expenditure and fat metabolism on top of the appetite-suppressing, insulin-modulating effects shared with the other two compounds. That's the basis for it being studied as a potentially more potent weight-loss agent than dual or single-receptor drugs.

What the trial data actually shows

The Phase 2 trial (registered as NCT04881760) enrolled adults with obesity or overweight without diabetes and tested four doses (1mg, 4mg, 8mg, 12mg) against placebo. At 24 weeks, the trial's primary endpoint showed mean weight reduction of up to 17.5% (about 18.7 kg) on the highest dose. A secondary endpoint at 48 weeks reported mean weight reduction of up to 24.2% (about 26.2 kg). The manufacturer describes retatrutide's safety profile in this trial as broadly similar to other incretin-based therapies, with gastrointestinal effects as the most common side effects.

Source: "Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial," (opens in new tab) The New England Journal of Medicine.

Eli Lilly has since moved retatrutide into Phase 3 trials, still investigating both obesity and type 2 diabetes indications. Phase 3 is the stage that, if successful, precedes a regulatory approval filing — it is not itself an approval, and results at this stage aren't final.

Side effects (trial data so far)

Retatrutide has no approved label, so there's no definitive safety profile yet — only what the Phase 2 trial reported. The most common adverse events were gastrointestinal: nausea, diarrhea, vomiting and constipation, mostly mild-to-moderate and more frequent during the dose-escalation period, consistent with the pattern seen for semaglutide and tirzepatide. The trial authors noted the overall safety profile looked broadly similar to other incretin-based therapies, but a Phase 2 trial's safety data is inherently less complete than an approved drug's label — smaller participant numbers, shorter follow-up, and no post-marketing surveillance. That incompleteness is itself a reason not to treat an unregulated retatrutide vial as safety-equivalent to an approved medicine.

South Africa status: retatrutide isn't a case of "approved elsewhere, not yet registered in South Africa" — it isn't approved anywhere, for anyone, at any dose. Any vial sold as "retatrutide" today, in South Africa or elsewhere, is being sold outside of any completed regulatory review. SAHPRA's public warnings about unregistered peptide products apply here with the least ambiguity of the three compounds on this site. See how we rate for our full regulatory framing.

Cost in South Africa

Prices for retatrutide sold as a research chemical vary by dose and vendor. Among the vendors we've verified: ReGen-X lists 10mg at R950 up to 30mg at R1,800, Peptide Labs South Africa lists 20mg at R1,680, and Noventra Pharma lists a 32mg self-mix vial at R1,550 (dropping to R1,450 each at 3+). Since retatrutide has no approved medical version anywhere, there's no pharmacy price to compare these against — every seller of it is, by definition, selling outside any completed regulatory review. See our vendor comparison for how we score these sellers on documentation and transparency.

Frequently asked questions

Is retatrutide approved anywhere?

No. Unlike semaglutide and tirzepatide, retatrutide has no regulatory approval in any country, for any indication — it's still in Phase 3 trials. Every vial sold as "retatrutide" today is being sold outside of any completed regulatory review, in South Africa or anywhere else.

When might retatrutide be approved?

Eli Lilly has moved it into Phase 3 trials for obesity and type 2 diabetes. Phase 3 is the stage that, if successful, precedes a regulatory approval filing — but results aren't final at this stage, and there's no confirmed approval timeline.

How much does retatrutide cost in South Africa?

Among vendors we've verified selling it as a research chemical, published prices range from roughly R950 to R1,800 depending on dose and vendor — see Cost in South Africa above. There's no pharmacy price to compare this against, since no approved medical version exists yet.

What are the side effects, if it's not even approved?

Only Phase 2 trial data exists so far — mostly gastrointestinal effects (nausea, diarrhea, vomiting, constipation), similar to semaglutide and tirzepatide. See Side effects above for why that trial-stage data is less complete than an approved drug's label.

Related guides

This page is educational information about a molecule and its trial history. It is not medical advice, not a recommendation to use retatrutide, and not an endorsement of any vendor.