Methotrexate
Introduction
The immune system plays a vital role in fighting infection, but sometimes, when someone has an autoimmune condition such as eczema, cells of the immune system can attack the body’s own tissues and cause inflammation. People with eczema have an impaired skin barrier, which means their skin is drier, so natural moisturising oils leak out and allergens from the environment can enter the skin. This combination triggers the skin’s immune-fighting cells to become over-active, causing itching, swelling and the skin becoming red or darker than a person’s usual skin colour, depending on skin tone. Methotrexate is an immunosuppressant medicine that dampens down the activity of these immune-system cells to reduce the skin inflammation caused in eczema.
As well as being used to treat eczema, methotrexate has been licensed for many years to treat a number of other inflammatory conditions, including psoriasis and rheumatoid arthritis. It can be used alone or in combination with other treatments. Eczema patients must take this drug only under the supervision of a specialist doctor, such as a dermatologist. It has been used by dermatologists to treat eczema for over 40 years.
How does methotrexate work?
Methotrexate works as an immunosuppressant medication: dampening down overactive inflammatory cells (neutrophils and monocytes), regulating the skin’s immune system (T cells), and altering immune signals (cytokines). Methotrexate targets cells of the immune system found in the skin that drive eczema.
It takes several weeks for methotrexate to accumulate inside cells. Therefore, once you start taking methotrexate, it can take up to 12 weeks before you notice any improvement in your skin. It is important that you continue the treatment even if you do not feel any benefit during the first 3-12 weeks (it is likely that the methotrexate is in fact working). Methotrexate usually significantly improves the severity of a person’s eczema, enabling them to reduce the amounts of topical treatments used and frequency of application (this does not include emollients, which still need to be applied regularly and liberally). As with any eczema treatment, methotrexate is not a cure.
If your eczema improves with methotrexate therapy, it can be discontinued after a course (often up to a year) or continued on a low dose longer term with appropriate monitoring by your GP and dermatologist.
When is methotrexate used?
Methotrexate is used to treat severe eczema, and is often recommended as a treatment for severe eczema that does not improve with topical steroids, topical calcineurin inhibitors and emollients. This can be because the eczema affects a large area of the body, or because the eczema does not respond sufficiently well to topical treatments alone.
Methotrexate is an effective treatment for severe eczema. In the largest high-quality study of methotrexate for adults with severe eczema, 40 per cent (4 in 10) of patients saw at least a 50 per cent improvement in their eczema after 12 weeks of treatment. Most patients in this study wanted to continue with methotrexate treatment, and after 24 weeks of treatment, there was a 50 per cent improvement in the overall eczema severity of the group.
Methotrexate is taken in tablet or injection form, once a week, on the same day each week. The injection is usually subcutaneous (under the skin) and can be self-administered. Methotrexate is usually started at a low dose, such as 5 mg, once a week (as 2.5 mg tablets). If there are no side effects, the dose is then increased weekly to a regular dose of 15-20 mg, once a week (as 2.5 mg and 10 mg tablets). The dose will be adjusted by your dermatologist according to your response to treatment and any side effects.
Methotrexate 2.5 mg and 10 mg tablets look similar, so you should always check the dose of your methotrexate and the strength of the tablets supplied by your dermatologist, nurse and pharmacist. Methotrexate can also be given as a liquid.
If you think you have the wrong strength tablets, do not take the medication. Instead, contact your dermatologist or specialist nurse. Too high a dose can cause serious side effects.