TRIAL RESULTS · SIDE EFFECTS
Retatrutide side effects
ANSWER
In 2 placebo-controlled trials with posted results, the most common side effects of Retatrutide were nausea 26.0% (placebo 8.7%), decreased appetite 17.9% (placebo 5.2%), Covid-19 14.9% (placebo 14.8%). Read from ClinicalTrials.gov on 2026-10-03. Not medical advice.
Trial register
Trials with posted results
2
with an arm on Retatrutide, of 41 registered
Against placebo
2
placebo-controlled trials
People in those trials
457
on Retatrutide · 115 on placebo
Read
2026-10-03
ClinicalTrials.gov
VS PLACEBO
Most common side effects, Retatrutide beside placebo
Share of people with each side effect in 2 placebo-controlled trials with posted results: 457 people on Retatrutide (all doses), 115 on placebo, same trials. Listed only when reported for at least half of the people on Retatrutide. Source: ClinicalTrials.gov, read 2026-10-03. Not medical advice.
ALL TRIALS
All 67 side effects reported
Every trial with posted results and an arm on Retatrutide (n ≥ 20), all phases, by people affected. Placebo is shown where placebo-controlled trials reported the same event. Comparator arms are not counted.
| Side effect | Organ system | Retatrutide | Placebo | Trials |
|---|---|---|---|---|
| Nausea | Gastrointestinal disorders | 26.0% (119 of 457) | 8.7% | 2 |
| Decreased appetite | Metabolism and nutrition disorders | 17.9% (82 of 457) | 5.2% | 2 |
| Covid-19 | Infections and infestations | 14.9% (68 of 457) | 14.8% | 2 |
| Diarrhoea | Gastrointestinal disorders | 14.2% (65 of 457) | 8.7% | 2 |
| Constipation | Gastrointestinal disorders | 10.7% (49 of 457) | 2.6% | 2 |
| Vomiting | Gastrointestinal disorders | 10.1% (46 of 457) | 1.7% | 2 |
| Fatigue | General disorders | 6.6% (30 of 457) | 2.6% | 2 |
| Lipase increased | Investigations | 5.5% (25 of 457) | 3.5% | 2 |
| Dizziness | Nervous system disorders | 4.8% (22 of 457) | 2.6% | 2 |
| Headache | Nervous system disorders | 4.4% (20 of 457) | 1.7% | 2 |
| Urinary tract infection | Infections and infestations | 4.2% (19 of 457) | 2.6% | 2 |
| Dyspepsia | Gastrointestinal disorders | 3.9% (18 of 457) | 1.7% | 2 |
| Upper respiratory tract infection | Infections and infestations | 3.7% (17 of 457) | 3.5% | 2 |
| Weight decreased | Investigations | 3.1% (14 of 457) | 0.0% | 2 |
| Hypertension | Vascular disorders | 5.2% (14 of 267) | 2.9% | 1 |
| Abdominal pain | Gastrointestinal disorders | 2.8% (13 of 457) | 1.7% | 2 |
| Gastrooesophageal reflux disease | Gastrointestinal disorders | 4.9% (13 of 267) | 1.4% | 1 |
| Early satiety | General disorders | 4.9% (13 of 267) | 5.7% | 1 |
| Nasopharyngitis | Infections and infestations | 2.6% (12 of 457) | 3.5% | 2 |
| Abdominal pain upper | Gastrointestinal disorders | 4.5% (12 of 267) | 2.9% | 1 |
| Blood creatine phosphokinase increased | Investigations | 4.1% (11 of 267) | 2.9% | 1 |
| Sinusitis | Infections and infestations | 2.0% (9 of 457) | 5.2% | 2 |
| Anaemia | Blood and lymphatic system disorders | 1.8% (8 of 457) | 0.0% | 2 |
| Abdominal distension | Gastrointestinal disorders | 2.6% (7 of 267) | 0.0% | 1 |
| Hyperaesthesia | Nervous system disorders | 2.6% (7 of 267) | 1.4% | 1 |
| Rash | Skin and subcutaneous tissue disorders | 2.6% (7 of 267) | 0.0% | 1 |
| Eructation | Gastrointestinal disorders | 3.2% (6 of 190) | 0.0% | 1 |
| Hypotension | Vascular disorders | 2.2% (6 of 267) | 0.0% | 1 |
| Amylase increased | Investigations | 1.9% (5 of 267) | 2.9% | 1 |
| Dizziness postural | Nervous system disorders | 1.9% (5 of 267) | 0.0% | 1 |
| Sensitive skin | Skin and subcutaneous tissue disorders | 1.9% (5 of 267) | 0.0% | 1 |
| Flatulence | Gastrointestinal disorders | 2.1% (4 of 190) | 0.0% | 1 |
| Allodynia | Nervous system disorders | 1.5% (4 of 267) | 0.0% | 1 |
| Pruritus | Skin and subcutaneous tissue disorders | 1.5% (4 of 267) | 0.0% | 1 |
| Pancreatitis acute | Gastrointestinal disorders | 0.7% (3 of 457) | 0.0% | 2 |
| Cough | Respiratory, thoracic and mediastinal disorders | 1.6% (3 of 190) | 0.0% | 1 |
| Vaginal infection | Infections and infestations | 0.9% (2 of 228) | 0.0% | 2 |
| Cardiac failure congestive | Cardiac disorders | 1.1% (2 of 190) | 0.0% | 1 |
| Faeces hard | Gastrointestinal disorders | 0.7% (2 of 267) | 0.0% | 1 |
| Erectile dysfunction | Reproductive system and breast disorders | 1.4% (2 of 139) | 0.0% | 1 |
| Cerebrovascular accident | Nervous system disorders | 0.7% (2 of 267) | 0.0% | 1 |
| Acute kidney injury | Renal and urinary disorders | 0.2% (1 of 457) | 0.9% | 2 |
| Vaginal haemorrhage | Reproductive system and breast disorders | 1.0% (1 of 100) | 0.0% | 1 |
| Atrial fibrillation | Cardiac disorders | 0.5% (1 of 190) | 0.0% | 1 |
| Cholecystitis chronic | Hepatobiliary disorders | 0.5% (1 of 190) | 0.0% | 1 |
| Cellulitis | Infections and infestations | 0.5% (1 of 190) | 2.2% | 1 |
| Osteomyelitis acute | Infections and infestations | 0.5% (1 of 190) | 0.0% | 1 |
| Fibula fracture | Injury, poisoning and procedural complications | 0.5% (1 of 190) | 0.0% | 1 |
| Diabetic ketoacidosis | Metabolism and nutrition disorders | 0.5% (1 of 190) | 0.0% | 1 |
| Basal cell carcinoma | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 0.5% (1 of 190) | 0.0% | 1 |
| Malignant melanoma | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 0.5% (1 of 190) | 0.0% | 1 |
| Chronic obstructive pulmonary disease | Respiratory, thoracic and mediastinal disorders | 0.5% (1 of 190) | 0.0% | 1 |
| Cardiac failure | Cardiac disorders | 0.4% (1 of 267) | 0.0% | 1 |
| Chest discomfort | General disorders | 0.4% (1 of 267) | 0.0% | 1 |
| Drowning | General disorders | 0.4% (1 of 267) | 0.0% | 1 |
| Cholecystitis acute | Hepatobiliary disorders | 0.4% (1 of 267) | 0.0% | 1 |
| Electrocardiogram qt prolonged | Investigations | 0.4% (1 of 267) | 0.0% | 1 |
| Clear cell renal cell carcinoma | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 0.4% (1 of 267) | 0.0% | 1 |
| Penile swelling | Reproductive system and breast disorders | 0.0% (0 of 90) | 0.0% | 1 |
| Abdominal hernia | Gastrointestinal disorders | 0.0% (0 of 190) | 2.2% | 1 |
| Lumbar spinal stenosis | Musculoskeletal and connective tissue disorders | 0.0% (0 of 190) | 2.2% | 1 |
| Spinal osteoarthritis | Musculoskeletal and connective tissue disorders | 0.0% (0 of 190) | 2.2% | 1 |
| Spinal fusion surgery | Surgical and medical procedures | 0.0% (0 of 190) | 0.0% | 1 |
| Transurethral prostatectomy | Surgical and medical procedures | 0.0% (0 of 90) | 4.5% | 1 |
| Coronary artery stenosis | Cardiac disorders | 0.0% (0 of 267) | 1.4% | 1 |
| Bone contusion | Injury, poisoning and procedural complications | 0.0% (0 of 267) | 1.4% | 1 |
| Blood calcitonin increased | Investigations | 0.0% (0 of 267) | 1.4% | 1 |
Source: ClinicalTrials.gov posted results, read 2026-10-03. A trial lists events above its own reporting threshold, so a rare event may be missing from some trials. Not medical advice.
QUESTIONS
Does retatrutide cause nausea?
In 2 placebo-controlled trials with posted results, 26.0% of people on retatrutide reported nausea, against 8.7% on placebo. Source: ClinicalTrials.gov, read 2026-10-03. Not medical advice.
Does retatrutide cause decreased appetite?
In 2 placebo-controlled trials with posted results, 17.9% of people on retatrutide reported decreased appetite, against 5.2% on placebo. Source: ClinicalTrials.gov, read 2026-10-03. Not medical advice.
Does retatrutide cause Covid-19?
In 2 placebo-controlled trials with posted results, 14.9% of people on retatrutide reported Covid-19, against 14.8% on placebo. Source: ClinicalTrials.gov, read 2026-10-03. Not medical advice.
Does retatrutide cause diarrhoea?
In 2 placebo-controlled trials with posted results, 14.2% of people on retatrutide reported diarrhoea, against 8.7% on placebo. Source: ClinicalTrials.gov, read 2026-10-03. Not medical advice.
Does retatrutide cause constipation?
In 2 placebo-controlled trials with posted results, 10.7% of people on retatrutide reported constipation, against 2.6% on placebo. Source: ClinicalTrials.gov, read 2026-10-03. Not medical advice.
REGISTERED STUDIES
41 registered clinical trials of Retatrutide
The 10 most recently updated are listed.
| 2023-503658-11-00 | J1I-MC-GZBK: A Master Protocol to Investigate the Efficacy and Safety of LY3437943 Once Weekly in Participants with Type 2 Diabetes Mellitus Who Have Obesity or Overweight: A Randomized Double-Blind, Placebo-Controlled Trial (TRIUMPH-2) Status: UNKNOWN · Updated 2026-09-29 |
|---|---|
| NCT06260722 | Effect of Retatrutide Compared With Semaglutide in Adult Participants With Type 2 Diabetes and Inadequate Glycemic Control With Metformin With or Without SGLT2 Inhibitor (TRANSCEND-T2D-2) Status: ACTIVE_NOT_RECRUITING · Updated 2026-09-28 |
| NCT07035093 | A Study of Retatrutide (LY3437943) in Participants Who Have Obesity or Overweight and Chronic Low Back Pain Status: ACTIVE_NOT_RECRUITING · Updated 2026-09-25 |
| NCT06383390 | The Effect of Retatrutide Once Weekly on Cardiovascular Outcomes and Kidney Outcomes in Adults Living With Obesity (TRIUMPH-Outcomes) Status: ACTIVE_NOT_RECRUITING · Updated 2026-09-24 |
| NCT07165028 | A Master Protocol of Multiple Agents in Adults With Metabolic Dysfunction-Associated Steatotic Liver Disease (SYNERGY-Outcomes) Status: RECRUITING · Updated 2026-09-22 |
| 2025-522674-36-00 | N1T-MC-MALO: A Master Protocol for a Randomized, Controlled, Clinical Trial of Multiple Pharmacologic Agents in Adult Participants With Metabolic Dysfunction-Associated Steatotic Liver Disease Who Are at Increased Risk of Developing Major Adverse Liver Outcomes (SYNERGY-Outcomes); N1T-MC-TZ01 Tirzepatide in participants with high-risk MASLD; N1T-MC-RT01 Retatrutide in participants with high-risk MASLD Status: UNKNOWN · Updated 2026-09-21 |
| NCT05929066 | A Study of Retatrutide (LY3437943) in Participants Who Have Obesity or Overweight Status: COMPLETED · Updated 2026-08-21 |
| 2024-511450-49-00 | J1I-MC-GZBP: A Phase 3, Randomized, Double-Blind Study to Evaluate the Efficacy and Safety of Retatrutide Compared to Tirzepatide in Adults Who Have Obesity Status: UNKNOWN · Updated 2026-08-14 |
| NCT07629401 | Pre-approval Expanded Access of Retatrutide (LY3437943) Status: AVAILABLE · Updated 2026-08-06 |
| NCT05882045 | A Study of Retatrutide (LY3437943) in Participants With Obesity and Cardiovascular Disease Status: COMPLETED · Updated 2026-07-30 |
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