Investigational · not FDA approved

Editorially reviewed · Last updated September 8, 2026 · How we review

Retatrutide Side Effects & Safety Data (2026)

Key findings

GI adverse events were common in retatrutide trials and were usually mild or moderate.
TRIUMPH-1 and TRIUMPH-4 rates describe different populations and durations; keep their tables separate.
Abnormal skin sensations were already reported in Phase 2. Dysesthesia also appears in current semaglutide and tirzepatide labels.
At 12 mg, adverse-event discontinuation was 11.3% in TRIUMPH-1 and 18.2% in TRIUMPH-4.
Phase 2 recorded pancreatitis and gallbladder events; small numbers cannot establish or exclude a causal risk.
A published DXA substudy found lean-mass loss; it did not prove muscle preservation. Retatrutide remains investigational.

Retatrutide Side Effects & Safety

Q: What are the side effects of retatrutide?

The most common retatrutide side effects in the TRIUMPH-4 Phase 3 trial (12mg, 68 weeks) were nausea (43.2%), diarrhea (33.1%), constipation (25.0%), vomiting (20.9%), dysesthesia (20.9%), and decreased appetite (18.2%). GI events are usually mild to moderate and peak during dose escalation. Discontinuation for adverse events was 18.2% at 12mg vs 4.0% on placebo. Full tables are in Side Effect Rates from TRIUMPH-4. Retatrutide is investigational and not FDA-approved.

Q: What are reta side effects?

"Reta" is shorthand for retatrutide. Reta side effects are the same trial-listed adverse events — predominantly GI symptoms plus the dose-dependent dysesthesia signal. See Most Common Side Effects at a Glance.

This is the full safety page for retatrutide side effects (also searched as reta side effects or GLP-3 side effects). Retatrutide (LY3437943), known informally as "GLP-3" (retatrutide), is an investigational triple-agonist weight-loss drug. Like other drugs in the GLP-1 class, the most common adverse events are gastrointestinal — nausea, diarrhea, constipation, and vomiting — usually mild to moderate and concentrated during dose escalation.

For diet tactics that reduce GI symptoms (shot-day soft foods, fiber ramp when constipated, protein when you cannot eat), see What to eat on reta and the protein target calculator. This page is the rates-and-risks reference: trial incidence, the dysesthesia signal, and class-level concerns.

This page retains the detailed 68-week TRIUMPH-4 table and adds 80-week TRIUMPH-1 results, reported in May 2026. Phase 2 publications provide further information about rare events and body composition. Trial adverse events are events observed during a study; they are not all necessarily caused by treatment.

Retatrutide has not been approved by the FDA. Rates below come from specific study populations and regimens, not a personal risk calculator. The evidence was reviewed on September 8, 2026.

Most Common Side Effects at a Glance

The most common side effects of retatrutide at the 12 mg dose, based on TRIUMPH-4 Phase 3 trial data (445 participants over 68 weeks):

Nausea — 43.2% (vs. 10.7% placebo)
Diarrhea — 33.1% (vs. 13.4% placebo)
Constipation — 25.0% (vs. 8.7% placebo)
Vomiting — 20.9% (vs. 0.0% placebo)
Dysesthesia (abnormal skin sensation) — 20.9% (vs. 0.7% placebo)
Decreased appetite — 18.2% (vs. 9.4% placebo)

Gastrointestinal symptoms (nausea, diarrhea, constipation, vomiting) are the most common, generally mild-to-moderate, and concentrated during dose escalation. Dysesthesia is an important signal, but it is not unique to retatrutide: current semaglutide and tirzepatide labels also report it. See the dysesthesia section for details.

Discontinuation rates due to adverse events: 12.2% at 9 mg, 18.2% at 12 mg, 4.0% on placebo.

Side Effect Rates from TRIUMPH-4

The TRIUMPH-4 trial (announced December 2025) tested retatrutide at 9mg and 12mg doses against placebo over 68 weeks in 445 adults with obesity and knee osteoarthritis. The most commonly reported adverse events were:

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Adverse Event	9mg	12mg	Placebo
Nausea	38.1%	43.2%	10.7%
Diarrhea	34.7%	33.1%	13.4%
Constipation	21.8%	25.0%	8.7%
Vomiting	20.4%	20.9%	0.0%
Decreased appetite	19.0%	18.2%	9.4%
Dysesthesia	8.8%	20.9%	0.7%

Discontinuation rates due to adverse events: 12.2% at 9mg, 18.2% at 12mg, and 4.0% for placebo. Eli Lilly noted that some discontinuations were attributed to "perceived excessive weight loss" rather than intolerable side effects.

The manufacturer’s topline release does not establish that rare or long-term risks are equivalent to placebo.

Source: Eli Lilly TRIUMPH-4 press release, December 2025

Newer TRIUMPH-1 Safety Results

TRIUMPH-1 studied 2,339 adults without diabetes over 80 weeks. Its rates should remain separate from TRIUMPH-4 because the population and study duration differ.

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Adverse event	4 mg	9 mg	12 mg	Placebo
Nausea	28.6%	38.4%	42.4%	14.8%
Diarrhea	25.2%	34.1%	32.0%	13.5%
Constipation	23.8%	25.9%	26.1%	10.9%
Vomiting	10.6%	22.8%	25.3%	4.8%
Dysesthesia	5.1%	12.3%	12.5%	0.9%
Urinary tract infection	7.5%	8.8%	8.4%	5.3%
Stopped because of adverse events	4.1%	6.9%	11.3%	4.9%

Lilly reported that most dysesthesia and urinary-tract-infection events resolved during treatment and that most affected participants continued treatment. This does not guarantee resolution for every person. TRIUMPH-1 primary report.

Gastrointestinal Side Effects

The most common side effects of retatrutide — nausea, diarrhea, constipation, and vomiting — are gastrointestinal (GI) in nature. This is consistent with the entire GLP-1 drug class. GLP-1 activity affects appetite signaling and gastrointestinal function, including gastric emptying. A slowed stomach alone does not explain every symptom.

Nausea

Nausea was the most frequently reported side effect in TRIUMPH-4, affecting 43.2% of participants at the 12mg dose compared to 10.7% on placebo. Nausea is typically most pronounced during the dose-escalation phase and tends to diminish as the body adjusts to the drug.

Diarrhea

Diarrhea affected approximately one-third of participants at both the 9mg (34.7%) and 12mg (33.1%) doses. This is consistent with rates seen in trials of other GLP-1 drugs and is generally classified as mild to moderate.

Constipation

Constipation occurred in 21.8% (9mg) to 25.0% (12mg) of participants, compared to 8.7% on placebo. Changes in gut function, intake, and hydration can contribute to constipation. Stomach emptying and bowel transit are different processes. It may seem contradictory that retatrutide causes both diarrhea and constipation, but different individuals respond differently, and the same person may experience both at different points during treatment.

Vomiting

Vomiting was reported in approximately 20% of participants at both active doses and 0% on placebo. Like nausea, vomiting is more common during dose escalation and tends to improve over time.

Decreased Appetite

Decreased appetite — reported in 18-19% of active-dose participants — is technically a side effect, but also one of the drug's primary mechanisms of action. The distinction matters: a symptom such as decreased appetite can be recorded as an adverse event, while the study separately measures weight-loss efficacy.

Dysesthesia: A New Safety Signal

One finding in TRIUMPH-4 that drew particular attention was dysesthesia — a condition in which normal sensations feel unusual or painful. This could include tingling, burning, numbness, or a heightened sensitivity to touch.

What the data shows

The Phase 2 obesity publication already reported cutaneous hyperesthesia and skin-sensitivity events in 7% of retatrutide-treated participants versus 1% with placebo. None were severe or serious or led to discontinuation. Terminology differed, but it is incorrect to say abnormal skin sensations were absent in Phase 2. Phase 2 report.

TRIUMPH-4 reported dysesthesia in 20.9% at 12 mg, 8.8% at 9 mg, and 0.7% with placebo; Lilly described events as generally mild and rarely leading to discontinuation. TRIUMPH-1 later reported 12.5%, 12.3%, and 0.9% for the corresponding groups. A single trial’s dose pattern is not a universal risk curve.

Why it matters

The mechanism is not established. Tingling, burning, numbness, or painful sensitivity can have several causes, so a new symptom should not automatically be attributed to the drug or dismissed as harmless.

Dysesthesia is also listed in Wegovy’s current prescribing information and Zepbound’s label. Rates depend on the regimen and trial. It is incorrect to describe it as exclusive to retatrutide or as proof of glucagon-related nerve damage.

What we don't know about dysesthesia

TRIUMPH-1 offers some reassurance that many events resolve during treatment. We still need clearer evidence on persistent symptoms, risk factors, and long-term outcomes. The studies do not prove that all symptoms disappear after stopping.

Dose-Dependent Side Effects and Titration

Higher-dose groups had more of some adverse events, but the pattern was not uniform: TRIUMPH-4 diarrhea was slightly more common at 9 mg than at 12 mg.

The titration schedule

Retatrutide trials used gradual, protocol-defined escalation. These are research regimens, not an approved prescribing schedule or instructions for using a purchased peptide vial. There is no FDA-approved retatrutide label.

Why titration matters

The Phase 2 obesity trial found that starting at 2 mg rather than 4 mg partly reduced gastrointestinal adverse effects. That supports supervised escalation; it does not establish a safe self-directed starting dose, split schedule, or conversion from another medicine.

How Side Effects Compare to Ozempic and Mounjaro

Retatrutide's GI profile is broadly similar to other incretin drugs. Cross-trial nausea rates from the landmark obesity programs:

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Drug	Dose	Trial	Nausea Rate	Notes
Semaglutide (Wegovy)	2.4mg	STEP 1	~44%	Different population and follow-up
Tirzepatide (Zepbound)	15mg	SURMOUNT-1	~31%	Separate trial; not a safety ranking
Retatrutide	12mg	TRIUMPH-4	~43%	Dysesthesia 20.9% in this trial

These percentages do not isolate the effect of the glucagon receptor or establish that one drug is safer. Study populations, duration, dose escalation, and reporting differ. Wegovy 2.4 mg is also a different regimen from Ozempic’s diabetes doses.

Dysesthesia appears in current semaglutide and tirzepatide labels as well as retatrutide studies. A comparison should use the relevant dose and trial, not assume the event is absent with approved drugs.

For a detailed comparison of retatrutide versus existing drugs, see Retatrutide vs Mounjaro vs Ozempic.

Cardiovascular Effects

TRIUMPH-4 reported improvements in cardiovascular risk markers in the retatrutide groups:

Systolic blood pressure reduced by 14.0 mmHg at the 12mg dose
Improvements in non-HDL cholesterol, triglycerides, and hsCRP (a marker of systemic inflammation)

These cardiometabolic benefits are consistent with effects seen across the GLP-1 drug class and are likely driven by a combination of weight loss and direct metabolic effects of the drug. Semaglutide has already demonstrated cardiovascular risk reduction in the SELECT trial, and retatrutide’s cardiovascular-event benefit remains unproven. TRIUMPH-3 reported exploratory event data in July 2026, but its confidence intervals did not establish risk reduction. Dedicated outcome evidence is still needed.

In the Phase 2 trial, the blood pressure improvements were large enough that 41% of participants in the combined 8 mg group and 30% in the 12 mg group discontinued at least one antihypertensive medication during the 48-week study (NEJM 2023).

Heart rate

Heart rate increased on retatrutide in a dose-dependent manner — a pattern shared with other drugs that activate the GLP-1 receptor. In the Phase 2 trial, the increase peaked at 24 weeks and then declined at 36 and 48 weeks, and the magnitude was "similar to those reported for GLP-1 receptor agonists" (NEJM 2023). Reported cardiac arrhythmias were mild to moderate, with one exception: a single severe adverse event of prolonged QT syndrome occurred in a participant who was also taking ondansetron — a medication independently known to prolong the QT interval. If you take medications that prolong the QT interval (some antiemetics, antibiotics, antipsychotics, antidepressants) or have a history of arrhythmia, discuss heart-rate and rhythm monitoring with your prescriber before starting any incretin therapy.

Source: Eli Lilly TRIUMPH-4 press release, December 2025

Class-Level Safety Concerns

Retatrutide activates GLP-1 as well as GIP and glucagon receptors. Approved incretin labels provide context, but retatrutide has no approved label and its own trial findings must be considered separately.

Thyroid cancer risk

Wegovy and Zepbound carry boxed warnings about thyroid C-cell tumors observed in rodents; whether they cause these tumors in humans is unknown. Both are contraindicated with a personal or family history of medullary thyroid carcinoma or MEN 2. It is inaccurate to say every GLP-1 drug has the same boxed warning or that retatrutide already has one.

Gallbladder events

Gallbladder events were recorded in the Phase 2 retatrutide obesity trial, including cholecystitis and gallstones; this is not merely a hypothetical concern. Rapid weight loss can also contribute to gallstones. The small trial cannot define an individual’s long-term risk. Phase 2 publication.

Pancreatitis

The Phase 2 obesity publication reported one serious acute-pancreatitis event. A rare event in a small study neither proves causation nor rules out a risk. Severe, persistent abdominal pain, especially with vomiting or pain extending to the back, needs prompt medical assessment; do not treat it as ordinary dose-escalation nausea.

Gastroparesis

Gastroparesis — delayed or absent stomach emptying — is a class-level concern because slowed gastric emptying is part of how GLP-1 drugs work. A 2023 JAMA cohort study of patients using GLP-1 agonists for weight loss quantified the real-world risk:

Drug	Gastroparesis incidence (per 1,000 person-years)	Observed cases
Semaglutide	9.1	4
Liraglutide	7.3	66
Bupropion-naltrexone	3.1	3

The adjusted hazard ratio was 3.67 (95% CI 1.15–11.90) for the pooled GLP-1 group, not a separate liraglutide estimate. The 3.31 figure was the pooled crude estimate, not a semaglutide-specific adjusted result. This observational study included few events and no retatrutide users, so it cannot supply a retatrutide risk percentage.

Severe nausea or vomiting is not itself a diagnosis of gastroparesis. The reviewed retatrutide reports do not establish a reliable incidence of diagnosed gastroparesis.

Warning signs that should prompt clinical evaluation include persistent vomiting that does not improve as the body adapts to a given dose, inability to keep down food or fluids, severe abdominal pain or bloating, or GI symptoms that continue between weekly doses rather than concentrating in the day or two after each injection.

Muscle and Bone Considerations

Substantial weight loss can include fat and lean tissue. Lean mass is not synonymous with skeletal muscle: it also includes water and other non-fat tissues.

What we know

A 2025 retatrutide DXA substudy in adults with type 2 diabetes measured body composition over 36 weeks. Of 189 enrolled participants, 103 completed treatment and both scheduled scans. Fat mass fell, and the proportion of lean-mass loss was broadly similar to other obesity treatments. It did not establish a muscle-preserving advantage from glucagon activity.

What we don't know

The substudy did not directly compare retatrutide with semaglutide or tirzepatide, establish effects in strength-trained adults, or settle long-term strength, function, and bone outcomes. Resistance exercise and adequate nutrition are relevant to weight management, but a particular diet or training plan has not been proven to eliminate retatrutide-associated lean loss. See muscle-loss evidence.

What We Don't Know Yet

Retatrutide’s evidence base now extends beyond the original 445-person, 68-week TRIUMPH-4 study. TRIUMPH-1 followed 2,339 participants for 80 weeks, with a selected extension to 104 weeks, and TRIUMPH-2 and -3 reported in July 2026. These advances do not settle:

Rare harms and safety with years of continuous use.
Persistent dysesthesia or its risk factors.
Clinically important drug interactions and safety in pregnancy or breastfeeding.
Safety in populations excluded or sparsely represented in trials.
The amount and timing of weight regain after retatrutide withdrawal.

Trial size and follow-up matter even after encouraging results. See clinical trials, pregnancy evidence, and stopping retatrutide.

Frequently Asked Questions

Is retatrutide safe?

Trials show substantial weight loss alongside frequent gastrointestinal adverse events and a dysesthesia signal. They also record rarer events requiring follow-up. Retatrutide is not FDA-approved, and a favorable trial summary does not establish safety for every patient, long-term use, or gray-market products.

What are the side effects of retatrutide?

The most common retatrutide side effects in the TRIUMPH-4 Phase 3 trial (12mg, 68 weeks) were nausea (43.2%), diarrhea (33.1%), constipation (25.0%), vomiting (20.9%), dysesthesia (20.9%), and decreased appetite (18.2%). GI events are usually mild to moderate and peak during dose escalation. Discontinuation for adverse events was 18.2% at 12mg vs 4.0% on placebo. Full tables are in Side Effect Rates from TRIUMPH-4. Retatrutide is investigational and not FDA-approved.

What are reta side effects?

"Reta" is shorthand for retatrutide. Reta side effects are the same trial-listed adverse events — predominantly GI symptoms plus the dose-dependent dysesthesia signal. See Most Common Side Effects at a Glance.

What is dysesthesia?

Dysesthesia means abnormal or unpleasant sensation, such as burning, tingling, or painful sensitivity. TRIUMPH-4 reported it in 20.9% at 12 mg versus 0.7% with placebo; TRIUMPH-1 reported 12.5% versus 0.9%, with most events resolving during treatment. It also appears in semaglutide and tirzepatide labels. The mechanism and risk of persistent symptoms remain uncertain. See the dysesthesia section.

Does retatrutide cause muscle loss?

Retatrutide-associated weight loss includes lean-mass loss. A 2025 DXA substudy in people with type 2 diabetes found a lean-loss proportion broadly similar to other obesity treatments. DXA lean mass is not a direct measure of skeletal muscle or strength, and the study did not prove that glucagon activity preserves muscle. See the body-composition evidence, protein calculator, and diet guide.

Are retatrutide side effects worse than Ozempic?

There is no completed direct comparison establishing that ranking. Similar nausea rates across selected studies do not prove equivalent safety, and Wegovy 2.4 mg trial data should not be presented as Ozempic dose data. Dysesthesia is also reported with semaglutide. See the drug comparison.

How common is gastroparesis on retatrutide?

A reliable incidence has not been established in the reviewed reports. Nausea, vomiting, or a category of severe GI events cannot be converted into a gastroparesis rate. A 2023 observational study found an association with semaglutide/liraglutide, but included no retatrutide users. Persistent vomiting, inability to keep fluids down, or severe abdominal symptoms need medical assessment.

How can I reduce the risk of gallstones on retatrutide?

Gallstones were recorded in retatrutide’s Phase 2 trial, and rapid weight loss is another risk factor. Avoid crash dieting and discuss nutrition, weight-loss pace, and symptoms with the study team or clinician. NIDDK guidance discusses preventive ursodiol in certain rapid-weight-loss settings; it is not a proven routine retatrutide add-on. Severe abdominal pain, fever, or jaundice needs prompt assessment.

Can retatrutide cause hair loss?

The selected common-event tables above do not establish a retatrutide-specific alopecia rate or prove it never occurs. Current Wegovy and Zepbound labels report hair loss. Rapid weight loss can trigger temporary shedding, but other causes are possible and receptor count does not predict who will be affected. Sudden, patchy, or persistent loss warrants assessment. See hair-loss evidence.

Does retatrutide raise your heart rate?

In the Phase 2 obesity trial, heart rate increased on retatrutide in a dose-dependent way, peaked at 24 weeks, and then declined at 36 and 48 weeks. The size of the increase was similar to what has been reported for GLP-1 receptor agonists like semaglutide (NEJM 2023). The trial's main paper does not list per-dose bpm changes — those numbers are in supplementary tables. Reported arrhythmias were generally mild or moderate, with one severe prolonged-QT event in a participant also taking ondansetron, a drug independently known to prolong the QT interval. At the same time, blood pressure improved — enough that 41% of participants in the combined 8 mg group discontinued at least one blood pressure medication during the study. Lower blood pressure is not proof of fewer cardiovascular events. TRIUMPH-3 has reported exploratory event data without establishing risk reduction; dedicated outcome evidence is still needed.

Does retatrutide affect kidney function?

Renal (kidney) events were tracked as an adverse event of special interest in the Phase 2 obesity trial, and they were rare. A renal event occurred in 4 of 337 participants overall (1%), with the same low rate in the placebo group (1 of 70) as across the retatrutide dose groups (3 cases spread across the 1 mg, 4 mg, and 8 mg arms) — these few events cannot establish or exclude a causal kidney risk. That said, kidney safety has not been established in people who already have significant renal impairment: the trials largely excluded severe kidney disease, so safety data in that population is limited. The relevant indirect risk with any potent GLP-1-class drug is dehydration — severe nausea, vomiting, or diarrhea during dose escalation can reduce fluid intake and, in turn, stress the kidneys (acute kidney injury has been reported with other GLP-1 drugs in the setting of significant GI fluid loss). Staying hydrated through the titration phase and reporting persistent vomiting or diarrhea to a clinician is the standard precaution. Existing kidney disease should be discussed with the study team when assessing trial eligibility and monitoring needs.

How much does retatrutide lower ApoB and other lipids?

A 2024 ESC conference abstract from the Phase 2 obesity trial reported ApoB reductions of up to 19.6% at 24 weeks and 24.2% at 48 weeks, and non-HDL cholesterol reductions of up to 22.2% and 26.9%. These are dose-group maxima, not expected results for everyone. ApoB is a protein measurement used to estimate atherogenic particle burden, not a direct particle count.

The abstract reported other lipid improvements, but did not give an Lp(a) treatment result. Changes in these markers do not prove fewer heart attacks or establish how much benefit is independent of weight loss.

Sources

Lilly. (2026). TRIUMPH-1 efficacy and safety results.
Coskun, T., et al. (2025). Retatrutide body-composition substudy.
Current U.S. prescribing information: Wegovy and Zepbound.
Lilly. (2026). TRIUMPH-2 and TRIUMPH-3 results.
Eli Lilly and Company. (2025). Lilly's retatrutide achieved significant weight loss and pain relief in adults with obesity and knee osteoarthritis. Press release.
Jastreboff, A.M., et al. (2023). Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. New England Journal of Medicine. DOI: 10.1056/NEJMoa2301972
Wilding, J.P.H., et al. (2021). Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). New England Journal of Medicine. DOI: 10.1056/NEJMoa2032183
Jastreboff, A.M., et al. (2022). Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). New England Journal of Medicine. DOI: 10.1056/NEJMoa2206038
Lincoff, A.M., et al. (2023). Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT). New England Journal of Medicine. DOI: 10.1056/NEJMoa2307563
ClinicalTrials.gov: NCT04881760 (Phase 2, Obesity), NCT04867785 (Phase 2, T2D)
Retatrutide Phase 2 lipid sub-analysis, presented at the European Society of Cardiology (ESC) Congress 2024 — ApoB, non-HDL-C, triglyceride, apoC-III, and LDL-particle changes (NCT04881760). Conference abstract
Sodhi, M., Rezaeianzadeh, R., Kezouh, A., Etminan, M. (2023). Risk of Gastrointestinal Adverse Events Associated With Glucagon-Like Peptide-1 Receptor Agonists for Weight Loss. JAMA. Full text
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Dieting & Gallstones. Full text
Alsuwailem, O.A., Alanazi, R., Almutairi, H.M., et al. (2025). Hair Loss Associated With Glucagon-Like Peptide-1 (GLP-1) Receptor Agonist Use: A Systematic Review. Cureus 17(9):e92454. DOI: 10.7759/cureus.92454

Questions to ask your doctor

Is a GLP-1 medication an appropriate option for my condition specifically?
What does the evidence actually show for my condition, versus weight loss alone?
What are the alternatives, and how do they compare for me?
What risks or monitoring apply given my health history?
What results would be realistic, and over what timeframe?

How we keep this honest

What this is: Educational information, not medical advice. It reports published research — it doesn’t recommend that you use, obtain, or supply anything.
Regulatory status: Retatrutide and similar peptides are investigational — not approved by the FDA or any regulator. Semaglutide and tirzepatide are prescription-only medicines, available only through a licensed prescriber.
Our standard: Every claim traces to a primary source. We label the strength of evidence and flag estimates as estimates — never as clinical fact.
No commercial ties: We don’t sell, supply, or link to suppliers of any medicine, and aren’t affiliated with any manufacturer.

Do not make decisions about your health without consulting a qualified healthcare provider. For trial enrolment, see ClinicalTrials.gov. More on how we review.

Sources

Grounded in primary sources

NEJM

The Lancet

JAMA

FDA

ClinicalTrials.gov

Retatrutide Side Effects & Safety

Most Common Side Effects at a Glance

Side Effect Rates from TRIUMPH-4

Newer TRIUMPH-1 Safety Results

Gastrointestinal Side Effects

Nausea

Diarrhea

Constipation

Vomiting

Decreased Appetite

Dysesthesia: A New Safety Signal

What the data shows

Why it matters

What we don't know about dysesthesia

Dose-Dependent Side Effects and Titration

The titration schedule

Why titration matters

How Side Effects Compare to Ozempic and Mounjaro

Cardiovascular Effects

Heart rate

Class-Level Safety Concerns

Thyroid cancer risk

Gallbladder events

Pancreatitis

Gastroparesis

Muscle and Bone Considerations

What we know

What we don't know

What We Don't Know Yet

Frequently Asked Questions

Is retatrutide safe?

What are the side effects of retatrutide?

What are reta side effects?

What is dysesthesia?

Does retatrutide cause muscle loss?

Are retatrutide side effects worse than Ozempic?

How common is gastroparesis on retatrutide?

How can I reduce the risk of gallstones on retatrutide?

Can retatrutide cause hair loss?

Does retatrutide raise your heart rate?

Does retatrutide affect kidney function?

How much does retatrutide lower ApoB and other lipids?

Sources

Questions to ask your doctor

Related reading

Retatrutide vs Mounjaro vs Ozempic

Retatrutide Phase 3 Results 2026: TRIUMPH Trial Tracker

What Is Retatrutide (GLP-3)?

TRIUMPH-3 Retatrutide Results: 22.6% at 12 mg

TRANSCEND-T2D-1: Published Retatrutide Phase 3 Diabetes Results

Retatrutide Dosage & Dosing Guide: Titration, Missed Doses, Taper

What to Eat on Reta: Protein, Shot Day & When You Can't Eat

Protein Target Calculator for Retatrutide

Does Retatrutide Cause Muscle Loss?

Retatrutide and Alcohol: What We Know