What is the relationship between alopecia and treatment with Methimazole (MMI)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: May 1, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Guidelines

Hair loss from methimazole treatment is typically temporary and often resolves even with continued treatment, and ensuring adequate nutrition with sufficient protein, iron, zinc, and vitamins, particularly vitamin D, can support hair health during treatment 1. If you're experiencing hair loss while taking methimazole for hyperthyroidism, don't stop your medication without consulting your doctor first. Your doctor might consider reducing your methimazole dose if your thyroid function tests allow it, as hair loss may be dose-dependent. In some cases, switching to an alternative treatment like propylthiouracil (PTU) might be considered, though PTU has its own side effect profile. It's essential to understand that both untreated hyperthyroidism and rapid normalization of thyroid function can cause temporary hair loss, so the medication may not be the only factor. Some key points to consider:

  • Vitamin D levels tend to be lower in patients with alopecia areata, and ensuring adequate vitamin D levels may help support hair health 1.
  • A diet rich in protein, iron, zinc, and vitamins can help support hair growth during treatment.
  • Most patients see hair regrowth within 3-6 months as the body adjusts to the medication or after the treatment course is completed.
  • If hair loss is severe or accompanied by other concerning symptoms like rash, joint pain, or fever, contact your doctor immediately as these could indicate a more serious reaction. The role of micronutrients, particularly vitamin D, in alopecia areata has been studied, and the evidence suggests that vitamin D deficiency may be associated with an increased risk of alopecia areata 1. However, more research is needed to fully understand the relationship between vitamin D and hair loss.

From the Research

Hair Loss from Methimazole Treatment

  • There is no direct evidence in the provided studies that links methimazole treatment to hair loss 2, 3, 4, 5, 6.
  • The studies primarily focus on the treatment of hyperthyroidism using methimazole and propylthiouracil, discussing their efficacy, safety, and side effects such as rash, pruritus, agranulocytosis, and hepatotoxicity 2, 3, 4, 5, 6.
  • None of the studies mention hair loss as a side effect of methimazole treatment, suggesting that it may not be a well-documented or common adverse effect of this medication 2, 3, 4, 5, 6.
  • Further research would be necessary to determine if there is any association between methimazole treatment and hair loss, as the current evidence does not provide a clear answer to this question 2, 3, 4, 5, 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Hyperthyroidism: Diagnosis and Treatment.

American family physician, 2016

Research

Desensitization to Methimazole.

Endocrine practice : official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists, 2021

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.