Methotrexate (MTX) is a common medication used to manage conditions like rheumatoid arthritis and psoriasis. MTX targets rapid cell division in inflammatory diseases, but this mechanism can affect other fast-growing cells in the body, leading to side effects. Hair loss, or alopecia, is one such side effect that can be distressing for patients. Understanding the cause of this thinning and knowing mitigation strategies can help manage this concern while maintaining the medication’s benefits.
Why Methotrexate Causes Hair Thinning
Methotrexate functions as an anti-folate drug by inhibiting an enzyme necessary for producing reduced folate. Folate, a B-vitamin, is required for DNA synthesis and cell division. By disrupting this process, MTX slows the proliferation of the immune or skin cells responsible for autoimmune inflammation.
Hair follicles contain some of the fastest-dividing cells in the body, especially during the active growth (anagen) phase. Because of their high metabolic rate, these cells become unintended targets of the drug. This interference weakens the hair shaft, leading to increased shedding and overall thinning.
This hair loss is generally mild and diffuse, occurring evenly across the scalp. At the low doses used for autoimmune conditions, hair loss is often a temporary increase in shedding. More severe hair loss is typically associated with the higher doses used in chemotherapy, which are less common in weekly regimens for arthritis or psoriasis.
Medical Strategies to Counteract Hair Loss
The most effective medical strategy to prevent MTX-related hair loss is the co-administration of folic acid or folinic acid. Methotrexate depletes the body’s folate stores, and supplementation supplies this nutrient to healthy cells, including hair follicles, without compromising the drug’s anti-inflammatory effect. A physician will prescribe a specific dosing schedule, often recommending the supplement be taken daily, except on the day of the MTX dose, or 8 to 12 hours afterward.
If standard folic acid is inadequate, a physician may prescribe folinic acid (leucovorin). Folinic acid is a more active form of the vitamin that more effectively bypasses the enzyme blocked by MTX, providing a stronger rescue effect for healthy cells. Any change in the type or dose of a folate supplement must be managed under medical supervision to ensure safety and maintain MTX efficacy.
If hair loss is significant and persistent, a physician may review the MTX regimen. They might recommend lowering the weekly dose or splitting the dose over 24 hours to reduce the peak concentration. Another strategy is switching from oral tablets to subcutaneous injection. Injectable MTX may improve absorption and potentially reduce side effects, including hair loss.
The doctor should also rule out other medical causes of hair loss, as the underlying inflammatory condition can cause shedding. Blood tests may check for conditions like thyroid dysfunction or iron-deficiency anemia, which independently contribute to thinning. Addressing these separate issues can significantly reduce the hair loss experienced while on MTX.
Daily Hair Care Practices for Mitigation
A gentle hair care routine reduces physical stress on vulnerable hair strands. When brushing, use a wide-tooth comb or soft brush and avoid aggressively pulling the hair, especially when wet. Avoid tight hairstyles like braids or ponytails that create tension on the roots (traction alopecia).
Washing hair less frequently can help, as most shedding occurs during shampooing. Use a mild, sulfate-free shampoo to minimize scalp irritation. When drying, gently blot hair with a soft towel instead of rubbing, and allow it to air dry whenever possible.
Heat is a major stressor for fragile hair. Minimize the use of heat styling tools like flat irons, curling irons, and high-heat blow dryers. Chemical treatments such as permanent dyes, bleaching, or perms weaken the hair structure and should generally be avoided during MTX-related thinning. Consult a healthcare provider before any chemical treatment.
Supporting hair health also involves balanced nutrition, focusing on adequate protein intake. Specific nutrients like iron, zinc, and biotin support the hair growth cycle. Always discuss any new supplement, such as biotin, with a doctor to ensure it does not interfere with the methotrexate treatment plan.
Expected Recovery and When to Consult a Specialist
Hair thinning caused by low-dose methotrexate is usually temporary. The hair growth cycle is resilient, and the body often adjusts, allowing shedding to stabilize. If the medication is successfully maintaining the underlying condition, thinning may stabilize, and regrowth typically begins once the body adapts or a dosage adjustment is made.
If MTX therapy is discontinued, increased shedding generally ceases, and hair regrowth usually begins within three to six months. Complete restoration of density may take six to twelve months as follicles cycle through natural growth phases. Documenting shedding patterns helps communication with the healthcare team.
Certain signs require immediate consultation with a specialist, such as a rheumatologist or dermatologist. These warning signs include a sudden, severe increase in hair loss or the development of distinct, round patches of baldness. These patterns are not typical of MTX-related thinning and could indicate a different condition, such as alopecia areata. A specialist should also be consulted if hair loss is accompanied by a painful scalp, rash, or persistent itching.