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Medications · Updated 2026-10-30 · Editorial review in progress
Levothyroxine hair loss in the first months of treatment
Also searched as: SynthroidLevoxylthyroid medicationlevothyroxine hair loss first months
Levothyroxine labelling says partial hair loss may occur rarely during the first few months of therapy and is usually temporary.
No consistent week-by-week window is published for this, so it is not on the calculator.
The timeline
| Stage | When (typically) | What's happening |
|---|---|---|
| Window | First few months of therapy | Partial hair loss may occur rarely during the first few months; usually temporary. [Pfizer] |
What the label says, word for word
The Levoxyl prescribing information tells clinicians to inform patients that "partial hair loss may occur rarely during the first few months" of therapy, and the Medication Guide says it "usually lasts a short period of time" [Pfizer]. No week is given, so levothyroxine is not on the calculator.
The thyroid itself matters too
NICE lists endocrine disorders including hypothyroidism among underlying causes of hair loss [NICE]. That's why a clinician may look at your thyroid levels rather than the tablet alone.
Normal vs. warning signs
- Mild, diffuse thinning in the first months
- Shedding that fades as treatment continues
- Patches or smooth bald spots
- Scalp pain, redness, burning or scaling
- Loss of eyebrows, eyelashes or body hair
- Palpitations, tremor, heat intolerance or weight loss — signs your dose may need review
What may help
- Never change your dose yourself; ask your prescriber about a thyroid level check.
- Note when treatment started or the dose changed.
- Ask whether iron should be checked too.
Related triggers
Stopping breastfeeding
Labs & explainersFerritin & iron
Labs & explainersVitamin D
MedicationsSertraline & SSRIs
Frequently asked questions
Is hair loss in the first months of levothyroxine normal?
The label says partial hair loss may occur rarely in the first few months and is usually temporary.
Does levothyroxine hair loss go away?
The Medication Guide says it usually lasts a short period of time.
Should I stop levothyroxine because of hair loss?
No. Talk to your prescriber; thyroid problems themselves can cause hair loss.
Sources
- Pfizer / FDA labeling. LEVOXYL (levothyroxine) patient counseling information & Medication Guide
- NICE Clinical Knowledge Summaries. Female pattern hair loss — differential diagnosis (telogen effluvium)