{"id":113,"date":"2026-07-22T08:51:05","date_gmt":"2026-07-22T08:51:05","guid":{"rendered":"https:\/\/findpeptideclinics.com\/blog\/?p=113"},"modified":"2026-09-09T08:12:57","modified_gmt":"2026-09-09T08:12:57","slug":"retatrutide-side-effects-phase-3-2026","status":"publish","type":"post","link":"https:\/\/findpeptideclinics.com\/blog\/retatrutide-side-effects-phase-3-2026\/","title":{"rendered":"Retatrutide Side Effects: What Phase 3 Shows in 2026"},"content":{"rendered":"

Retatrutide remains investigational and is not FDA approved. Across Lilly’s 2026 sponsor-reported Phase 3 topline releases, the most frequently disclosed adverse events were gastrointestinal, including nausea, diarrhea, constipation, vomiting, or decreased appetite, with dysesthesia and urinary tract infections also reported in some trials. These TRIUMPH topline releases do not replace full peer-reviewed reports, and FDA says retatrutide cannot be compounded under federal law.<\/p>\n

Evidence checked August 16, 2026.<\/strong> Study-arm labels below describe trial data, not dosing guidance.<\/p>\n

Scope clarification, September 8, 2026:<\/strong> The TRIUMPH-1, -2 and -3 findings summarized here come from sponsor topline releases. This is not a claim that no Phase 3 retatrutide paper exists. The separate TRANSCEND-T2D-1 study in adults with type 2 diabetes was published in The Lancet in June 2026<\/a>. Its population and study design differ; it should not be substituted for the TRIUMPH safety tables below.<\/p>\n

\nRetatrutide status<\/strong><\/p>\n

FDA status:<\/strong> FDA has not approved retatrutide for any condition.
\nRegistry status:<\/strong> TRIUMPH-1, TRIUMPH-2, and TRIUMPH-3 are complete; their current ClinicalTrials.gov records do not post results.
\nPublic evidence summarized on this page:<\/strong> TRIUMPH-1, -2 and -3 sponsor topline releases; see the scope clarification above for the separate published diabetes trial.
\nCompounding status:<\/strong> FDA states that retatrutide cannot be used in compounding under federal law.\n<\/div>\n

Editorial review:<\/strong> Find Peptide Clinics Editorial Desk. See how we verify sources and separate editorial work from paid listings<\/a>. No clinician reviewer is named for this article.<\/p>\n

Direct answer: what Phase 3 currently shows<\/h2>\n

Lilly’s three sponsor-reported Phase 3 topline releases describe gastrointestinal events as the most frequent adverse events across the disclosed study arms. The releases also report dysesthesia and urinary tract infections in each trial. TRIUMPH-3 included people with severe obesity and established cardiovascular disease. Lilly reported cardiovascular estimates with wide confidence intervals that do not establish benefit or harm.<\/p>\n

The releases do not provide the complete public safety dataset. They do not replace a peer-reviewed paper, a ClinicalTrials.gov results record, or an FDA review.<\/p>\n

The evidence ladder: published, topline, registry, and FDA<\/h2>\n
\n\n\n\n\n\n\n\n\n
Evidence layer<\/th>\nWhat it contributes<\/th>\nLimit<\/th>\n<\/tr>\n<\/thead>\n
Peer-reviewed<\/strong><\/td>\nPublished research includes the Phase 2 obesity trial and the separate TRANSCEND-T2D-1 Phase 3 diabetes trial<\/a>.<\/td>\nTheir populations and designs differ; neither is the source of this page’s TRIUMPH safety tables.<\/td>\n<\/tr>\n
Sponsor-topline<\/strong><\/td>\nLilly reported selected TRIUMPH-1, -2, and -3 results in press releases.<\/td>\nA sponsor release reports what the sponsor disclosed. It is not independent verification or FDA review.<\/td>\n<\/tr>\n
Registry<\/strong><\/td>\nClinicalTrials.gov records trial design, status, enrollment, and dates.<\/td>\nThe three records do not post results as checked August 16, 2026.<\/td>\n<\/tr>\n
Official regulatory<\/strong><\/td>\nFDA states the drug’s approval and federal compounding status.<\/td>\nFDA has not approved retatrutide or reviewed a marketed retatrutide product.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

TRIUMPH-1: adults without type 2 diabetes<\/h2>\n

ClinicalTrials.gov lists TRIUMPH-1 (NCT05929066)<\/a> as a completed Phase 3 trial with an actual enrollment of 2,335 and a primary completion date of April 6, 2026. The registry does not post results as checked. Lilly’s May 21 release<\/a> says the sponsor randomized 2,339 participants. The sources use different counts, so this article keeps both labels rather than merging them.<\/p>\n

Source type:<\/strong> Sponsor-reported topline; not peer-reviewed as checked August 16, 2026.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n
Reported event<\/th>\n4 mg arm<\/th>\n9 mg arm<\/th>\n12 mg arm<\/th>\nPlacebo<\/th>\n<\/tr>\n<\/thead>\n
Nausea<\/td>\n28.6%<\/td>\n38.4%<\/td>\n42.4%<\/td>\n14.8%<\/td>\n<\/tr>\n
Diarrhea<\/td>\n25.2%<\/td>\n34.1%<\/td>\n32.0%<\/td>\n13.5%<\/td>\n<\/tr>\n
Constipation<\/td>\n23.8%<\/td>\n25.9%<\/td>\n26.1%<\/td>\n10.9%<\/td>\n<\/tr>\n
Vomiting<\/td>\n10.6%<\/td>\n22.8%<\/td>\n25.3%<\/td>\n4.8%<\/td>\n<\/tr>\n
Upper respiratory tract infection<\/td>\n14.2%<\/td>\n12.2%<\/td>\n13.1%<\/td>\n11.6%<\/td>\n<\/tr>\n
Dysesthesia<\/td>\n5.1%<\/td>\n12.3%<\/td>\n12.5%<\/td>\n0.9%<\/td>\n<\/tr>\n
Urinary tract infection<\/td>\n7.5%<\/td>\n8.8%<\/td>\n8.4%<\/td>\n5.3%<\/td>\n<\/tr>\n
Discontinuation due to adverse events<\/td>\n4.1%<\/td>\n6.9%<\/td>\n11.3%<\/td>\n4.9%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

The 11.3% discontinuation figure describes one study arm. The topline release cannot establish an individual’s risk, the cause of a specific event, or comparative safety outside the trial.<\/p>\n

TRIUMPH-2: adults with type 2 diabetes and obesity or overweight<\/h2>\n

ClinicalTrials.gov lists TRIUMPH-2 (NCT05929079)<\/a> as completed with an actual enrollment of 1,152 and a primary completion date of June 16, 2026. The registry does not post results as checked. Lilly’s July 23 release<\/a> also reports 1,152 participants.<\/p>\n

Source type:<\/strong> Sponsor-reported topline; not peer-reviewed as checked August 16, 2026.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n
Reported event<\/th>\n4 mg arm<\/th>\n9 mg arm<\/th>\n12 mg arm<\/th>\nPlacebo<\/th>\n<\/tr>\n<\/thead>\n
Diarrhea<\/td>\n27.4%<\/td>\n33.5%<\/td>\n33.6%<\/td>\n13.2%<\/td>\n<\/tr>\n
Nausea<\/td>\n13.7%<\/td>\n20.8%<\/td>\n28.0%<\/td>\n8.0%<\/td>\n<\/tr>\n
Constipation<\/td>\n14.0%<\/td>\n16.2%<\/td>\n16.8%<\/td>\n9.4%<\/td>\n<\/tr>\n
Decreased appetite<\/td>\n5.8%<\/td>\n12.3%<\/td>\n17.1%<\/td>\n4.5%<\/td>\n<\/tr>\n
Vomiting<\/td>\n5.5%<\/td>\n10.2%<\/td>\n15.7%<\/td>\n4.2%<\/td>\n<\/tr>\n
Dysesthesia<\/td>\n4.5%<\/td>\n5.6%<\/td>\n7.3%<\/td>\n0.7%<\/td>\n<\/tr>\n
Urinary tract infection<\/td>\n3.8%<\/td>\n6.3%<\/td>\n8.0%<\/td>\n6.6%<\/td>\n<\/tr>\n
Discontinuation due to adverse events<\/td>\n3.8%<\/td>\n11.6%<\/td>\n7.7%<\/td>\n4.9%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

TRIUMPH-3: severe obesity and established cardiovascular disease<\/h2>\n

ClinicalTrials.gov lists TRIUMPH-3 (NCT05882045)<\/a> as completed with an actual enrollment of 1,946 and a primary completion date of April 16, 2026. The registry does not post results as checked. Lilly’s July 23 release says the sponsor randomized 1,949 participants. The sources use different counts.<\/p>\n

Source type:<\/strong> Sponsor-reported topline; not peer-reviewed as checked August 16, 2026.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n\n
Reported event<\/th>\n9 mg arm<\/th>\n12 mg arm<\/th>\nPlacebo<\/th>\n<\/tr>\n<\/thead>\n
Diarrhea<\/td>\n30.1%<\/td>\n24.4%<\/td>\n8.7%<\/td>\n<\/tr>\n
Nausea<\/td>\n21.7%<\/td>\n22.4%<\/td>\n5.8%<\/td>\n<\/tr>\n
Constipation<\/td>\n18.0%<\/td>\n15.7%<\/td>\n7.1%<\/td>\n<\/tr>\n
Decreased appetite<\/td>\n13.5%<\/td>\n14.5%<\/td>\n3.0%<\/td>\n<\/tr>\n
Hyperglycemia<\/td>\n3.9%<\/td>\n3.1%<\/td>\n13.4%<\/td>\n<\/tr>\n
Dysesthesia<\/td>\n6.4%<\/td>\n6.4%<\/td>\n1.3%<\/td>\n<\/tr>\n
Urinary tract infection<\/td>\n6.1%<\/td>\n7.0%<\/td>\n5.3%<\/td>\n<\/tr>\n
Discontinuation due to adverse events<\/td>\n9.8%<\/td>\n13.5%<\/td>\n4.8%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
\nCardiovascular uncertainty:<\/strong> Lilly reported an in-study MACE-5 hazard ratio of 0.82 with a 95% confidence interval of 0.55 to 1.22. The release reported a MACE-3 hazard ratio of 1.12 with a 95% confidence interval of 0.64 to 1.96. Both intervals cross 1.0. These topline estimates do not establish benefit or harm.\n<\/div>\n

What the Phase 3 topline releases still do not answer<\/h2>\n