We tend to think of chemotherapy specifically as a treatment for cancer. More than 100 unique chemotherapy drugs are available to fight various types of cancer. Depending on the particular drug, the medication may slow the cancer’s growth or act to destroy cancer cells.

Although psoriasis isn’t a type of cancer, some chemotherapy medications have been found to be effective in treating it. They include the drug methotrexate, as well a class of drugs called psoralens that are used in a treatment called photochemotherapy. Read on to learn more about these chemotherapy options and how they can help treat psoriasis.

Like cancer, psoriasis is a disease in which healthy cells are attacked. Psoriasis doesn’t begin with a tumor, though. It’s an autoimmune disease that occurs when the body’s immune system mistakenly attacks healthy skin cells. This attack causes inflammation and excessive production of skin cells, which leads to dry, scaly patches of skin. These patches often occur on the elbows, knees, scalp, and torso.

Psoriasis is a chronic condition without a cure, but it does have many possible treatments. An important goal of these treatments is to slow down the growth of newly forming cells, which is what the following chemotherapy options can do.

The U.S. Food and Drug Administration approved methotrexate for the treatment of psoriasis in the 1970s. At that time, the drug was already a well-established cancer medication. Since then, it has become a mainstay in psoriasis treatment because it helps decrease the production of new skin cells. It’s typically used to treat severe psoriasis.

Methotrexate can be injected or taken orally. It’s often used along with other psoriasis treatments, such as topical creams and light therapy.

Side effects and risks of methotrexate

Methotrexate is usually well-tolerated, but there are some precautions. It’s not recommended for people with liver or kidney problems. You should also avoid this drug if you have anemia or if you’re pregnant or breastfeeding.

Your doctor may recommend a folic acid (vitamin B) supplement to help protect against some of the side effects of methotrexate.

If you take this medication, you’ll need to have regular blood tests done to see how your body is responding to the drug. You should also know that this medication can cause liver scarring. Liver problems can be made worse if you consume a lot of alcohol or if you’re obese.

The second type of chemotherapy used to treat psoriasis is called photochemotherapy.

Phototherapy, which involves shining an ultraviolet (UV) light on an area of skin affected by psoriasis, is a common treatment. The light helps slow down the body’s production of skin cells. This treatment can be done in different ways. If you have a small area affected by psoriasis, you can use a handheld UV light wand to treat the area. If the patches cover large sections of skin, you can stand in a phototherapy booth to receive an all-over light treatment.

Phototherapy used in combination with medication is called photochemotherapy, or PUVA. This treatment uses a class of medications called psoralens in combination with ultraviolet A light to treat the affected skin. The psoralen, which you take two hours before having the light therapy, is a light-sensitizing medication. It makes your skin more responsive to certain types of UV light therapy.

The only psoralen approved in the United States is called methoxsalen (Oxsoralen-Ultra). Methoxsalen comes as an oral capsule.

Like phototherapy, PUVA can be localized or cover your whole body. It’s an aggressive form of therapy and is generally used only in serious cases.

Side effects and risks of photochemotherapy

The potential side effects associated with photochemotherapy are mostly seen on the skin, such as redness or itching. However, nausea and headache can sometimes follow treatments.

Long-term potential skin problems can include:

Because psoralen causes sensitivity to UV light, it puts you at increased risk of sunburn. You should take extra precautions with sunlight while the drug is still in your system, even in conditions that don’t seem threatening. Be sure to avoid the sun in the hottest part of the day and wear sunscreen with an SPF of at least 30.

These chemotherapy drugs may be effective for some people, but they’re not for everyone. Psoriasis affects people differently, and each person’s response to a particular treatment can vary, too.

If you have psoriasis, discuss the range of treatment options available to you with your doctor. And before undergoing any long-term therapy, talk about any potential side effects with your doctor. Working together, you can find a treatment plan that helps relieve your symptoms and improve your quality of life.