Evidence explainerWomen's GLP-1 & Weight
Hair Shedding on Semaglutide or Tirzepatide: How Common It Is in Women, and Whether Iron Matters
Hair loss is a labeled side effect of both Wegovy and Zepbound, and in tirzepatide's trials women reported it far more often than men. Low iron is one known trigger of shedding, but the evidence for iron pills without anemia is thin.
Key takeaways
- In Zepbound's weight-loss trials, hair loss was reported by 4% to 5% of people on tirzepatide vs 1% on placebo, and by 7.1% of women vs 0.5% of men on the drug; no one on tirzepatide stopped treatment because of it [1].
- Wegovy's label lists hair loss in 3% of adults on semaglutide 2.4 mg vs 1% on placebo [2].
- Zepbound's label says the hair loss was associated with weight reduction [1], and a 2026 systematic review found telogen effluvium (sudden shedding) and pattern hair loss were the main types reported, with rapid weight loss a likely contributor [3].
- Iron deficiency, crash dieting and low protein intake are all recognised triggers of telogen effluvium [4].
- A dermatology review found insufficient evidence to recommend iron supplements for hair loss in people with low iron who are not anemic; a ferritin test can confirm iron deficiency but reads falsely high during inflammation [5].
How common it is
In the two pooled Zepbound weight-reduction trials, hair loss was reported by 5%, 4% and 5% of people on the 5 mg, 10 mg and 15 mg doses vs 1% on placebo [1]. Women were affected far more often: 7.1% of women vs 0.5% of men on tirzepatide, and 1.3% vs 0% on placebo [1].
Wegovy's label lists hair loss in 3% of adults on semaglutide 2.4 mg vs 1% on placebo [2]. These figures come from different trials, so they cannot be compared head to head.
Why it happens
Telogen effluvium is diffuse shedding of resting hairs after a metabolic stress, hormonal change or medicine; common triggers include crash dieting, low protein intake, iron deficiency, hypothyroidism and postpartum hormonal changes [4].
Zepbound's label ties the hair loss in its trials to weight reduction [1]. A 2026 systematic review of 24 studies found semaglutide and tirzepatide had the highest reported rates among GLP-1 drugs, that females appeared disproportionately affected, and that rapid weight loss emerged as a potential contributor; the authors say causality still needs prospective trials [3].
Iron and ferritin
In premenopausal women the most common cause of iron deficiency is menstrual blood loss [5]. Hemoglobin can be used to screen for iron deficiency and serum ferritin to confirm it, but ferritin can be raised by infection, inflammation and some cancers, so other iron tests are sometimes needed [5].
Studies linking low iron to hair loss in women are mixed, and the review found insufficient evidence to recommend routine iron screening for everyone with hair loss, or iron supplements for hair loss in people who are iron deficient but not anemic; it leaves both to clinical judgment [5]. See our iron monograph for doses and side effects.
What to raise with your clinician
The 2025 GLP-1 nutrition advisory lists excessive hair loss among the signs of nutrient deficiency during treatment and recommends reassessing intake and nutrient levels during therapy [6]. Points worth raising:
Partners we link to
- GalaPaid linkWomen-focused online weight care: compounded semaglutide or tirzepatide (not FDA-approved) at a published flat $179/mo on a yearly subscription, visits and shipping included (checked Oct 8, 2026). LegitScript certified.See Gala's GLP-1 plans
- FoundPaid linkWeight care with named board-certified clinicians: brand-name GLP-1 prescriptions (medication billed separately, insurance accepted) or compounded semaglutide and tirzepatide, which are not FDA-approved. LegitScript certified.See Found's weight plans
Quick answers
Is hair loss more common on tirzepatide or semaglutide?
Their labels report 4% to 5% for tirzepatide and 3% for semaglutide 2.4 mg, but from different trials [1][2]. A 2026 review found both had the highest reported rates among GLP-1 drugs [3].
Should I take iron for hair shedding on a GLP-1?
Only if tests show you need it. A dermatology review found insufficient evidence for iron supplements for hair loss in people who are not anemic [5].
More in Women's GLP-1 & Weight
- Women's GLP-1 & Weight hub
- Semaglutide vs Tirzepatide: How Much Weight the Trials Showed, and What Happens When You Stop
- Compounded Semaglutide and Tirzepatide: What the FDA Actually Says, and the Red Flags to Check
- GLP-1s, the Pill and Pregnancy: The Label Warnings Women Need Before Starting
- GLP-1s and Muscle: How Much Lean Mass Women Lose, and the Protein and Strength Plan Experts Recommend
- GLP-1s With PCOS or After Menopause: What the Evidence Shows
References
- [1]ZEPBOUND (tirzepatide) injection: prescribing information. U.S. Food and Drug Administration (Drugs@FDA), 2026.
- [2]WEGOVY (semaglutide) injection and tablets: prescribing information. U.S. Food and Drug Administration (Drugs@FDA), 2026.
- [3]GLP-1 therapies and hair loss: A systematic review of current evidence and implications for counseling. Sci Prog, 2026.
- [4]Telogen Effluvium (StatPearls). StatPearls Publishing, 2024.
- [5]The diagnosis and treatment of iron deficiency and its potential relationship to hair loss. J Am Acad Dermatol, 2006.
- [6]Nutritional priorities to support GLP-1 therapy for obesity: A joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society. Obes Pillars, 2025.