context: Psoriasis is a serious medical condition caused by a problem with your immune system. There is no cure. There are treatments, though, that can get rid of the raised, red, scaly patches on your skin and make your skin smoother. These include topical treatments you put on your skin, light therapy, pills, shots, and infusions (drugs put directly into your bloodstream with a small needle and a tube). Each comes with its own possible side effects. Your doctor can help you weigh the risks and benefits of any treatment. These are medicines you rub on your skin, including your scalp. If you have mild or moderate psoriasis, one of these may be all you need to control it. In more severe cases, you may use one along with other treatments. Corticosteroids: These powerful drugs ease inflammation and can help a lot. But you shouldn't use them over a long period. They can make your skin thinner and may stop working as well. Vitamin D: Topical treatments that have vitamin D, like calcipotriene and calcitriol, can irritate your skin. Anthralin: This medicine makes skin cells grow more slowly and helps get rid of scales. The most common side effect is skin irritation. It also can stain your skin as well as clothing, fabric, and even hard surfaces. It's best to let it stay on your skin only for a short time and then wash it off. Tazarotene: This is a retinoid cream, which means it's made from vitamin A. It can irritate your skin and make you more sensitive to sunlight. It's not recommended for women who are pregnant or plan to get pregnant because it can raise your chances of having a child with certain birth defects. Salicylic acid: This helps get rid of dead skin cells. It also may irritate your skin. If you use it on your scalp over a long period, it could make your hair weak and possibly fall out. Coal tar: This thick, black byproduct of coal can slow down the growth of skin cells, ease inflammation, help with itching and scaling, and make your skin look better. But it also can irritate and dry out your skin and make you more sensitive to sunlight. Ultraviolet light targeted at problem areas can help control psoriasis outbreaks. But it should be done only under a doctor's care. Common side effects are minor burns and a higher risk of skin cancer. It also can make you more sensitive to sunlight. With photochemotherapy, which includes a drug that makes the ultraviolet light work better, short-term side effects also include nausea, itching, and red skin. When treatments like creams, ointments, shampoos, and phototherapy don't do enough to control your psoriasis, you may need to take medicine. Retinoids: These drugs made from vitamin A can raise your chances of liver problems. Your doctor will do regular blood tests to watch for that. They also bring a risk of birth defects, so women who take them shouldn't get pregnant for at least 3 years afterward. Other possible side effects include: Depression Dry, cracked skin or lips Hair loss Joint pain Nosebleeds Trouble seeing in the dark Methotrexate: This drug, usually taken as a pill or shot, slows the growth of skin cells and eases inflammation. Its side effects can include: Feeling tired Loss of appetite Upset stomach If you take it for a long time, methotrexate can cause more serious issues, such as liver damage and problems with your blood cells. Cyclosporine: This drug slows down your immune system. That can increase your risk of an infection or other health problem, including cancer. You also can have kidney damage or high blood pressure if you take it for a long time. Biologics: These are strong drugs made from living cells. Because they affect your immune system, they can raise your chances of a serious infection, including tuberculosis. It's important to know about the side effects of any treatment your doctor recommends. Some questions you may want to ask include: What serious side effects should I watch for and when should I call for medical help? What can I do to help manage the side effects of my medication? What should I know about being in the sun? What are my options if I can't handle the side effects of this drug? Is it safe if I'm thinking about getting pregnant?