Question 1

What makes retatrutide different from semaglutide and tirzepatide?

Accepted Answer

Retatrutide is a triple agonist that activates three receptors: GIP, GLP-1, and glucagon. Semaglutide activates only GLP-1. Tirzepatide activates GIP and GLP-1. The addition of glucagon receptor agonism in retatrutide increases energy expenditure and promotes hepatic fat oxidation — effects not produced by pure GLP-1 or dual GIP/GLP-1 agonism. This triple mechanism produced 24.2% weight loss in Phase 2 trials, exceeding both semaglutide (~15%) and tirzepatide (~21%).

Question 2

Is retatrutide FDA-approved?

Accepted Answer

No. Retatrutide is currently in Phase 3 clinical trials (the TRIUMPH program) conducted by Eli Lilly. It has not been submitted to the FDA for approval. Phase 3 results are expected between 2025 and 2027. If results confirm Phase 2 findings, an FDA submission could follow, with potential approval in the 2027-2028 timeframe.

Question 3

Can I buy retatrutide?

Accepted Answer

Retatrutide is available from research peptide vendors as a research chemical, not for human use. It cannot be legally prescribed or compounded for clinical use because it has no FDA-approved version. Purchasing research peptides for self-administration carries significant legal and safety risks, including unknown purity, lack of medical supervision, and potential legal liability. TriedRx tracks 48 vendors and 312 samples for quality data, but does not endorse self-administration of unapproved compounds.

Question 4

How much weight loss does retatrutide produce?

Accepted Answer

In the Phase 2 trial, retatrutide at 12mg produced 24.2% average body weight loss over 48 weeks. The weight-loss curve had not plateaued at 48 weeks, suggesting longer treatment could produce even greater loss. At 8mg, weight loss was 22.8%. These results exceed all other anti-obesity drugs tested to date. Phase 3 trials will confirm whether these results hold in larger populations.

Question 5

What are the side effects of retatrutide?

Accepted Answer

The most common side effects in Phase 2 were gastrointestinal: nausea (22-35%), diarrhea (22-30%), vomiting (6-19%), constipation (13-16%), and decreased appetite (9-28%). A small increase in resting heart rate (~3-4 bpm) was observed, possibly related to the glucagon agonist component. The discontinuation rate due to adverse events was approximately 6% at the highest dose. Full safety profiles will be available from the Phase 3 TRIUMPH program.

Question 6

Does retatrutide help with fatty liver disease?

Accepted Answer

Yes, retatrutide showed remarkable effects on liver fat in Phase 2. Participants receiving 12mg experienced an average 82-86% reduction in liver fat measured by MRI, and 93% of those with MASLD at baseline achieved liver fat normalization. These results likely reflect the glucagon receptor's role in promoting hepatic fat oxidation. Eli Lilly is conducting a dedicated Phase 3 trial (TRIUMPH-3) for MASH based on these findings.

Question 7

When will retatrutide be available?

Accepted Answer

If Phase 3 results are positive and regulatory review proceeds on schedule, retatrutide could receive FDA approval in approximately 2027-2028. However, drug development timelines are subject to delays from clinical, manufacturing, or regulatory factors. There is no guarantee of approval — Phase 3 results must confirm Phase 2 efficacy and safety findings in larger populations.

#	Vendor	Avg score	Purity range	Tests	Verified $/mg	Grade	Profile
Grade B+ — Very Good
1	Peptide Partners	8.8	99.3 – 100.0%	19	$3.50	B+	review →
2	Aavant Research	8.5	98.8 – 100.0%	8	—	B+	review →
Grade B — Good
3	Polaris Peptides	7.3	98.4 – 99.6%	26	—	B	review →
4	Paradigm Peptide	7.0	98.9 – 100.0%	14	—	B	review →

Vendor Rankings

Retatrutide Rankings