Retatrutide — frequently asked questions

Retatrutide is an investigational once-weekly injectable medication developed by Eli Lilly. It is a triple hormone receptor agonist, meaning it activates three metabolic receptors at once: GLP-1 (reduces appetite and slows digestion), GIP (enhances insulin response and fat metabolism) and glucagon (increases energy expenditure and fat burning). No currently approved weight-loss medication targets all three pathways simultaneously.

No. Retatrutide is not yet available to the public anywhere in the world, including Australia. It is an investigational medication still completing Phase 3 clinical trials. Eli Lilly plans to file for regulatory approval in 2027, after which the TGA would review it for the Australian market.

No. Retatrutide has not been approved by the Therapeutic Goods Administration (TGA) in Australia or the FDA in the United States. It remains an investigational drug available only through official Eli Lilly clinical trials.

Eli Lilly plans to file for regulatory approval in 2027. After filing, the TGA review process typically takes many months. Based on current timelines, the earliest realistic availability in Australia would be late 2027 or 2028, though no date is guaranteed.

In the landmark TRIUMPH-1 Phase 3 trial, participants on the highest dose (12 mg) lost an average of 70.3 lbs (31.9 kg), or 28.3% of their body weight, over 80 weeks. In a 104-week extension, average loss reached 85 lbs (38.5 kg) — 30.3% of body weight. 45.3% of participants on 12 mg lost 30% or more of their body weight.

Ozempic/Wegovy (semaglutide) targets one receptor (GLP-1). Mounjaro/Zepbound (tirzepatide) targets two (GLP-1 and GIP). Retatrutide targets three — GLP-1, GIP and glucagon. The glucagon component increases the body's energy expenditure, so retatrutide does not just reduce how much you eat — it also increases how much energy you burn. Trial results show correspondingly greater average weight loss.

The most common side effects in trials were nausea (especially early in treatment), diarrhoea, constipation, vomiting, and dysesthesia (a generally mild, temporary nerve sensation). These are consistent with other GLP-1-based medications, were mostly manageable, and most participants continued treatment.

Retatrutide is a once-weekly subcutaneous injection, similar to existing GLP-1 medications like Ozempic and Mounjaro. In trials, doses were escalated gradually from a low starting dose to improve tolerability.

You should not purchase anything claiming to be retatrutide outside of an official Eli Lilly clinical trial. Unregulated products may contain harmful contaminants, incorrect dosing, or entirely different ingredients. Eli Lilly actively works with law enforcement to combat black-market versions of this drug.

Eli Lilly's Phase 3 program is studying retatrutide for obesity and overweight (with comorbidities), type 2 diabetes, knee osteoarthritis pain, moderate-to-severe obstructive sleep apnoea, chronic low back pain, cardiovascular and renal outcomes, and metabolic dysfunction-associated steatotic liver disease (MASLD). Over 5,800 participants have been enrolled across the TRIUMPH program globally.