The short answer: nobody can give you a retatrutide hair-loss rate yet, because none appears in Lilly's 2026 trial releases, the trial abstracts or the phase 2 results. Hair loss is still a realistic possibility, since tirzepatide's label reports it in 7.1% of women and retatrutide produced more weight loss in its own trials.
Status as of November 6, 2026: Retatrutide is investigational. It isn't approved by the FDA or any regulator, and Lilly plans to file for U.S. approval in Q1 2027. Every label number below is for an approved drug, not retatrutide. Nothing here is medical advice or a dosing guide.
Key takeaways
No retatrutide hair-loss rate appears in Lilly's 2026 trial releases, the TRIUMPH-1 and TRIUMPH-2 abstracts, or the phase 2 abstract and posted results. The full journal tables are paywalled, so a number could be sitting there.
In the 338-person phase 2 obesity trial, no group reached the 5% reporting cutoff for hair loss on ClinicalTrials.gov. That caps it. It doesn't clear it.
Zepbound's label: hair loss in 4% to 5% of people vs 1% on placebo, and 7.1% of women vs 0.5% of men.
The usual pattern is telogen effluvium: shedding 2 to 4 months after a trigger. The American Academy of Dermatology says hair tends to regain its fullness within six to nine months.
Whether the cause is the drug or the weight loss is unproven. No prospective controlled study has tested it for this drug class, and a PubMed search finds no retatrutide hair data.
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Does reta cause hair loss? What the trials actually reported
Here's what each retatrutide source says:
Source | Who | What it says about hair loss |
|---|---|---|
Phase 2 obesity, NEJM 2023 abstract | 338 adults, 48 weeks | Not mentioned. Full paper not readable |
Phase 2 posted results, obesity and diabetes trials | 338 and 281 adults | Not listed; cutoff is 5% in any group |
TRIUMPH-1 and TRIUMPH-2, abstracts and Lilly releases | 2,339 and 1,152 adults, 80 weeks | Not mentioned. Full tables not readable |
TRIUMPH-3, Lilly release | Topline only | Not mentioned |
Ozempic head-to-head, Lilly release | 1,298 adults, 80 weeks | Not mentioned |
Sources: NEJM, 2023, NCT04881760 results, NCT04867785 results, TRIUMPH-1, NEJM, 2026, TRIUMPH-2, Lancet, 2026, Lilly, June 6, 2026, Lilly, July 23, 2026, Lilly, Sept 29, 2026, Lilly, Oct 28, 2026.
"Not mentioned" isn't "didn't happen." Trial papers in this class usually report events at 5% or more, and hair loss rarely made the cut even for drugs where it's on the label (Piraccini et al., 2026).
The phase 2 posted results do give a ceiling. In the 33- to 35-person groups, hair loss hit one person at most. In the 62-person 12 mg group, three at most. That rules out any big phase 2 number, including the 13.9% that has circulated online. It doesn't rule out 3% to 5%, which is where the approved drugs sit. Phase 2 also ran 48 weeks, not 80.
One retatrutide-specific count exists, and it isn't a rate. A JAMA Network Open study of social media posts found alopecia in 50 of 7,823 retatrutide users with a coded symptom, or 0.6% (Sehgal et al., Oct 2026). Those are unprompted posts, product identity can't be verified, and the authors call the findings "hypothesis-generating."
What's the hair loss rate on Zepbound and other GLP-1s?
About 3% to 6% overall on the labels, with women far above men. Each label says hair loss was "associated with weight reduction".
Drug and label dose | All patients vs placebo | Women vs placebo | Men vs placebo | Weight change, top dose, no-diabetes trial |
|---|---|---|---|---|
Foundayo 5.5 to 17.2 mg | 4% to 5% vs 2% | 7% vs 3% | 0.9% vs 0.7% | -11.1% at 72 weeks |
Wegovy shot 2.4 mg | 3.3% vs 1% | 4% vs 2% | 0.9% vs 0% | -14.9% at 68 weeks |
Wegovy shot 7.2 mg | 5.8% vs 1.0% | 8.4% vs 1.5% | 0.2% vs 0% | -18.8% at 72 weeks |
Zepbound 5 to 15 mg | 4% to 5% vs 1% | 7.1% vs 1.3% | 0.5% vs 0% | -20.9% at 72 weeks |
Retatrutide (not approved) | Not reported | Not reported | Not reported | -25.0% at 80 weeks, 12 mg |
Sources: Zepbound label, Aug 2026, Wegovy label, June 2026, Foundayo label, July 2026, TRIUMPH-1, NEJM, 2026. Separate trials and pools, so this is context, not a ranking. The hair columns pool trials that include people with diabetes. The pill data is in Wegovy pill vs Foundayo.
It's not a clean ladder. Foundayo produced the least weight loss here, and women's hair loss on it matched Zepbound's. The tidiest comparison sits inside the Wegovy program: moving from 2.4 mg to 7.2 mg took weight change from -15.5% to -18.8% in the same obesity trial, and hair loss from 3.3% to 5.8% across its trials. That's a higher dose as well as more weight loss, so it can't separate the two.
Labels may run low. In a small self-report survey of 152 GLP-1 users in Saudi Arabia, 87.5% of them women, 70.4% reported shedding (Alharbi and Alkhalifah, 2026).
Retatrutide's -25.0% is further than any drug on that table, which is the reason to expect shedding to show up. That's reasoning, not data. More in retatrutide vs tirzepatide and is reta safe?
Want the retatrutide number when it's readable? Get BHN updates. When a rate is published, this post gets updated.
Is reta hair loss from the drug or the weight loss?
Most likely the weight loss, but nobody has proven it. A 2026 dermatology commentary says "No prospective, controlled studies have specifically evaluated this issue" and that "causality has not been established" (Piraccini et al., 2026).
Evidence pointing at weight loss:
Surgery does it too. Hair loss hit a pooled 57% of people after bariatric surgery, with no drug involved (Zhang et al., 2021).
More loss, more shedding. In the Saudi survey, 82.7% of people who lost 15% or more reported shedding, vs 40% of those who lost under 5%.
Tirzepatide vs surgery. In a records study of over 360,000 adults with obesity, tirzepatide's telogen effluvium risk wasn't significantly different from bariatric surgery's (hazard ratio 1.61, 95% CI 0.65 to 3.99) (Neubauer et al., tabulated in Piraccini, 2026). That interval is wide, so it's weak evidence of sameness.
Evidence that it may not be the whole story:
Tirzepatide vs other weight-loss drugs. That same records study found higher risk than with other weight-loss drugs (hazard ratio 2.65, 95% CI 1.32 to 5.32).
A possible direct route. GLP-1 receptors were found in mouse hair follicles. A direct effect on human hair "has not been proven" (Piraccini et al., 2026).
Retatrutide adds a question nobody has touched: it also hits the glucagon receptor. A PubMed search on November 6 for retatrutide with alopecia or hair loss returned two reviews, and neither abstract gives a retatrutide hair figure (Leite Junior and Ribeiro Junior, 2026; Narla and Narla, 2026). So any claim that glucagon makes hair loss better or worse is a guess.
When does shedding start, and what does it look like?
Usually two to four months after the trigger, so it shows up well after the weight starts moving.
DermNet puts the increased hair fall at 2 to 4 months after the event (DermNet). For drug-linked shedding, the commentary above says about 3 months after starting.
For scale, the American Academy of Dermatology says 50 to 100 hairs a day is normal, and lists "Lost 20 pounds or more" among the stressors behind excessive shedding (AAD).
Telogen effluvium thins hair across the whole scalp, without bald patches. Bald patches, or slow thinning focused on the top of the head, point to something else (Seyed Jafari et al., 2026).
Does hair grow back after reta hair loss?
If it's telogen effluvium, it usually does. For retatrutide specifically, there's no data.
AAD: as the body readjusts, shedding stops, and hair tends to regain its fullness within six to nine months. That's general guidance, not GLP-1 data.
GLP-1 review: regrowth expected within 3 to 6 months once weight stabilizes, and complete regrowth in 6 to 12 months (Seyed Jafari et al., 2026).
GLP-1 users who stopped: in the Saudi survey, 37.7% reported resolution after stopping. That's a one-time survey.
Two catches. First, time. The AAD warns that if a stressor stays with you, shedding "can be long lived." One commentary says "the hair loss will stop after the weight loss stops," and that whether hair regrows when a GLP-1 is stopped still needs confirming. TRIUMPH-1 ran 80 weeks, so weight loss on reta may be a long trigger. That's inference, not a finding.
Second, not all thinning is shedding. A 2026 meta-analysis tied GLP-1 use to androgenetic (pattern) hair loss as well as telogen effluvium (Viquez Burboa et al., 2026). Pattern loss is progressive, and the GLP-1 review notes it's commonly found alongside telogen effluvium. So some people's hair may not return to where it was.
That review suggests a dermatology referral if the diagnosis is unclear or nothing improves after 3 to 6 months. It was written for approved drugs under medical care. Retatrutide isn't one, and its legal routes are narrow.
Reta hair loss in women: is it worse?
There's no retatrutide data split by sex. On every approved drug above, women reported far more of it: 7.1% vs 0.5% on Zepbound, 8.4% vs 0.2% on Wegovy 7.2 mg.
Female sex was also an independent predictor in the Saudi survey (odds ratio 3.57, 95% CI 1.20 to 11.11), and a 2026 review named female sex and weight loss over 10% as the most robust predictors (Leite Junior and Ribeiro Junior, 2026). Until Lilly publishes otherwise, the label pattern is the best available guide.
What labs do doctors check for hair loss on a GLP-1?
There's no standard panel for this. Cleveland Clinic says telogen effluvium can usually be diagnosed without testing, with blood work added if another cause is suspected (Cleveland Clinic). These are the markers the sources name:
Marker | Why it comes up | Source |
|---|---|---|
Ferritin (iron stores) | Often low in telogen effluvium; lower levels tied to hair loss after bariatric surgery | Seyed Jafari 2026; Zhang 2021 |
TSH (thyroid) | Thyroid problems are a known trigger of shedding | Seyed Jafari 2026; DermNet |
Vitamin D | Listed among common lab findings in telogen effluvium | Seyed Jafari 2026 |
Zinc | Lower levels tied to hair loss after bariatric surgery | Zhang 2021 |
Folate, B12 | DermNet names both; the bariatric link held for folate, not B12 | DermNet; Zhang 2021 |
The bariatric links are associations in surgery patients, not GLP-1 users. A low result is something to take to a clinician, not proof of the cause.
Baseline panels, including CBC and TSH, are in blood work before peptides. Ferritin, vitamin D and zinc aren't on that list, so they're add-ons to ask about.
Retatrutide hair loss FAQ
How long after starting reta would hair loss begin?
Nobody has published that for retatrutide. For telogen effluvium in general, shedding starts about 2 to 4 months after the trigger, and one commentary puts drug-linked shedding around 3 months after starting.
Is reta hair loss permanent?
Telogen effluvium usually resolves. Pattern hair loss is progressive and can show up alongside it. No retatrutide study has followed hair over time, so nobody can promise a result.
Do men lose hair on GLP-1 drugs?
Much less often in the trials. Men's rates on the labels run from 0.2% to 0.9%. There's no retatrutide number for men either.
Is there a hair loss percentage for retatrutide?
Not in any source that could be opened and checked as of November 6, 2026. The phase 2 posted results keep hair loss below 5% in every group, so double-digit phase 2 figures don't hold up.
If you've had shedding on reta or any GLP-1, reply and tell me when it started, how much weight you'd lost by then, and what your labs showed.
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