Does Methotrexate Cause Hair Thinning?
Yes, methotrexate can cause hair thinning or hair loss (alopecia). This side effect occurs in up to 3% of patients on low-dose therapy for rheumatoid arthritis or psoriasis, and more frequently at higher doses used in cancer treatment. It typically involves diffuse thinning rather than complete baldness and is usually reversible after stopping or reducing the dose.[1][2]
How Common Is Hair Loss with Methotrexate?
Hair thinning affects about 1-3% of patients on weekly low doses (7.5-25 mg) for autoimmune conditions. In chemotherapy settings (higher doses like 1-5 g/m²), rates climb to 10-65%, depending on regimen and patient factors. Women and those on long-term therapy report it more often.[1][3]
Why Does Methotrexate Thin Hair?
Methotrexate inhibits dihydrofolate reductase, disrupting DNA synthesis and rapidly dividing cells like hair follicles. This leads to telogen effluvium, where hairs prematurely enter the resting phase and shed. Factors like dose, duration, folate deficiency, or concurrent drugs (e.g., NSAIDs) worsen it.[2][4]
How Long Until Hair Loss Starts and Recovers?
Thinning often begins 1-3 months after starting treatment. Recovery starts 2-3 months after dose reduction or discontinuation, with full regrowth in 3-6 months for most. Persistent cases may need dermatologist evaluation.[1][3]
What Can Patients Do About It?
- Take folic acid supplements (1-5 mg daily, excluding treatment day) to reduce side effects by 80% without losing efficacy.[2]
- Lower dose or switch to alternatives like leflunomide if severe.
- Use minoxidil topically or gentle hair care; avoid heat styling.
Consult a doctor before changes—abrupt stops risk disease flare.[4]
Who Is at Higher Risk?
Patients with low body weight, older age, kidney issues, alcohol use, or genetic factors metabolizing methotrexate slowly face higher odds. Combination with drugs like trimethoprim or proton pump inhibitors amplifies risk.[1][3]
Alternatives If Hair Loss Is a Concern
For rheumatoid arthritis/psoriasis: Hydroxychloroquine, sulfasalazine, or biologics like adalimumab have lower alopecia rates (<1%). In cancer, switch to non-folate antagonists like pemetrexed analogs. Biosimilars may offer similar profiles at lower cost.[2]
[1]: Mayo Clinic. Methotrexate (oral route). https://www.mayoclinic.org/drugs-supplements/methotrexate-oral-route/side-effects/drg-20084837
[2]: American College of Rheumatology. Methotrexate Information. https://rheumatology.org/patients/methotrexate
[3]: Drugs.com. Methotrexate Side Effects. https://www.drugs.com/sfx/methotrexate-side-effects.html
[4]: UpToDate. Methotrexate Drug Information. https://www.uptodate.com/contents/methotrexate-drug-information