Methotrexate is an immunosuppressant and chemotherapy drug used to treat a variety of conditions. These include cancers of the blood, bone, breasts, and lungs.

Methotrexate is also an antirheumatic drug. It’s used to relieve symptoms of rheumatoid arthritis, psoriasis, and other autoimmune conditions.

But while the drug can improve certain conditions, it isn’t without side effects.

Unwanted hair loss is one possible side effect of methotrexate. If you take this drug for cancer or an inflammatory condition, here’s what you need to know about its possible effects on your hair.

Living with cancer or rheumatoid arthritis has its share of challenges. Dealing with hair loss on top of a health problem can be discouraging.

But although hair loss is a possibility with methotrexate, it isn’t a widespread side effect. According to the Arthritis Foundation, it only affects about 1 to 3 percent of people who take the medication. However, in studies of psoriasis patients, the rate of hair loss is higher: approximately 3 to 10 percent.

If you experience hair loss related to methotrexate, you may notice breakage around your hairline and abnormal shedding when washing or styling your hair.

Keep in mind that most people shed about 50 to 100 strands of hair per day, notes the American Academy of Dermatology. In the case of methotrexate hair loss, however, you may have more shedding than normal.

Hair loss occurs gradually over time and isn’t usually drastic. In other words, you’re not likely to lose patches of hair. Speak with your doctor if you’re experiencing severe hair loss or if your hair is falling out in clumps. This could indicate another underlying condition, such as alopecia areata.

If you have male or female pattern baldness, methotrexate could exacerbate your condition, resulting in increased thinning or hairline recession.

Methotrexate is effective against certain diseases because it stops the growth of cells. In the case of cancer, it stops the growth of malignant cells to slow the progression of the disease. With psoriasis, the medication slows the growth of new skin cells.

The problem with methotrexate is that it can also target hair follicles, which are cells responsible for hair growth. This causes unwanted hair loss. Methotrexate can also deplete the body of folate, a B-vitamin that may help with hair growth.

Even though hair loss doesn’t happen to everyone who takes methotrexate, it can occur whether you’re on a low dose or a high dose. However, a higher dose could result in more hair loss.

Methotrexate can be taken as a regular prescription to treat certain conditions. There are also instances when you might receive a single dose of the drug, such as in the case of an ectopic pregnancy. In this situation, the medication can stop the growth of an egg that has implanted outside the uterus.

In single-dose uses like this, hair loss and other side effects are uncommon, but can occur. Side effects tend to develop when taking the medication regularly.

The fact that methotrexate can cause hair loss might be confusing, considering that the drug is sometimes used to treat hair loss.

If you’re diagnosed with alopecia areata or discoid lupus, you may experience hair loss. Discoid lupus can cause lesions and permanent scarring on the scalp, and alopecia areata can cause inflammation that damages the hair follicles.

Both can stop hair growth. But if you take methotrexate to suppress your immune system and stop inflammation, you may reverse scarring and hair follicle damage. This can stimulate new hair growth.

One study evaluated 31 people with alopecia areata on methotrexate. The study found that 67.7 percent of participants had regrowth greater than 50 percent while on methotrexate.

About 77 percent of participants who took methotrexate in combination with a corticosteroid had regrowth greater than 50 percent.

Since hair loss due to methotrexate can be minor, you may decide to remain on the medication and live with thinning or shedding. This is an option, especially if your hair loss isn’t noticeable.

Nonetheless, talk to your doctor about taking a B-complex vitamin. This vitamin is important for healthy hair, although it doesn’t promote hair growth. You can also ask your doctor about reducing your dosage of methotrexate or taking an alternative drug.

If reducing your dosage isn’t an option, your rheumatologist can refer you to a dermatologist to see if you’re a candidate for hair regrowth treatments.

Methotrexate hair loss doesn’t happen to everyone who takes the medication. If it does occur, it may raise concerns. The upside is that hair loss from methotrexate is often temporary and reverses itself once you reduce your dosage or stop taking the medication.

Remember, hair loss related to the drug isn’t usually severe. So, speak with your doctor if you develop balding or lose patches of hair, as this may be a sign of another underlying condition.