context: Moderate to severe psoriasis describes how much of your body is covered in red, scaly psoriasis patches. Moderate psoriasis covers 3% to 10% of your body. Severe psoriasis covers more than 10% of your body or is on sensitive areas like your face, palms, soles, or skin folds. Knowing that you have moderate or severe psoriasis helps your doctor decide on a treatment. But it's not the only thing involved in choosing a treatment. You may have moderate psoriasis that really bothers you and want to start on a strong treatment. Or you may have more severe psoriasis that you barely notice and want to start with a milder treatment. Your doctor will also consider these things when helping you choose a treatment: The type of psoriasis you have How much psoriasis affects your life Your health Treatment costs to you Your doctor may use the Koo- Menter Psoriasis Instrument to help decide which treatment you need. This one-page tool asks questions to find out how much psoriasis is affecting your life. Usually, doctors start with the mildest treatments. If the first treatment doesn't work, you'll move up to stronger and stronger treatments until you find one that clears or controls your psoriasis. If you have very severe psoriasis, you may need to take more than one of these drugs at a time. Sometimes adding ultraviolet light or sunlight to a psoriasis pill, injection, or cream can help it work better. Even though everyone with psoriasis is different, doctors have a few standard treatments that they try in people with moderate to severe psoriasis. These include: Light therapy (phototherapy) Medications that suppress your immune system or target specific immune responses linked to psoriasis These treatments aim to slow down the rapid skin cell growth in psoriasis. They can also help smooth out scaly skin and reduce inflammation. Your dermatologist may have told you to stay out of the sun to prevent skin cancer and aging. But in people with psoriasis, the sun's ultraviolet A and B ( UVA and UVB) rays can actually help clear the skin. Some doctors recommend sitting outside in the sun for a few minutes a day. Or you can try an indoor light therapy that simulates UVA or UVB rays. Here are three types of light therapy for psoriasis. 1. Ultraviolet B ( UVB) Therapy What it is: Ultraviolet B ( UVB) therapy uses the same type of ultraviolet radiation found in sunlight. It's used to treat psoriasis that doesn't respond to creams and lotions. How it works: Your body is exposed to UVB light from a light box in a doctor's office or at home. The UVB light goes into your skin and slows skin cell growth. Types of UVB therapy: Broadband UVB therapy. This releases a wide band of ultraviolet light. Narrow-band UVB therapy. This releases a narrow band of ultraviolet light to target small areas of the skin. Goeckerman therapy. You apply coal tar to the skin before being exposed to UVB light. ( This is infrequently used and only available at a few centers.) Side effects can include skin irritation, redness, a burning or itching sensation, blisters, dry skin, sunburn, and a higher risk for skin cancer. 2. PUVA Therapy ( Photochemotherapy) What it is: You use a medicine called psoralen, which makes your skin more sensitive to light. Then you are exposed to ultraviolet A ( UVA) light. How it works: Psoralen is either applied to your skin or you take it by mouth. Thirty minutes to 2 hours later, your skin is exposed to ultraviolet A light. The light slows skin cell growth. Side effects can include nausea (from oral psoralens), itching, redness, burns, blisters, freckles or aged skin, cataracts if you don't wear sunglasses, and a higher risk for skin cancer, including melanoma. 3. Laser Treatment What it is: A form of light therapy that uses lasers. How it works: A thin beam of light targets psoriasis without affecting nearby skin. Laser types: Excimer laser. This releases a focused, high-intensity beam of ultraviolet light. Pulsed dye laser. This destroys the tiny blood vessels that support the formation of psoriasis plaques. Side effects can include redness, blistering, bruising, or scarring. Medications that you take by pill or injection affect the whole body. Your doctor may recommend one of these types of drugs if you haven't responded to topical creams or light therapy. 1. Cyclosporine What it is: Cyclosporine ( Neoral) is used to prevent organ rejection in transplant patients. It is also approved for treating psoriasis. How it works: It suppresses the immune system and slows the growth of certain immune cells. Cyclosporine is given by capsule or liquid. Side effects can include flu-like symptoms, headache, high blood pressure, higher cholesterol, sensitive skin, tingling in the arms or legs, upset stomach, fatigue, kidney damage, excess hair growth, and an increased risk for cancer. 2. Methotrexate What it is: A drug that was first used to treat cancer. How it works: Methotrexate slows the rate of skin cell growth. Methotrexate can be given by pill, liquid, or injection. Side effects can include nausea, vomiting, fatigue, headache, lightheadedness, easy bruising and bleeding, fever, mouth ulcers, trouble sleeping, sensitivity to sunlight, hair loss, dry cough, shortness of breath, stomach pain, a blistering or peeling rash, blood in your pee or poop, peeing less often, and liver damage. Pregnant women are at risk of having a baby with birth defects while taking this drug. Methotrexate can also affect sperm, so men should avoid this medication if trying to have a baby. 3. Biologic Treatments What it is: Biologic drugs target the immune response that causes inflammation. How it works: Biologics block immune cells that are involved in psoriasis. These drugs are given by a shot or by an IV infusion. Biologic drugs include: Ixekizumab ( Taltz) and secukinumab ( Cosentyx). These are antibodies that bind to interleukin-17 A, a protein that is involved in inflammation. Guselkumab ( Tremfya) and risankizumab-rzaa ( SKYRIZI). These medicationsselectively block interleukin-23 ( IL-23) and are given by injection. Tumor necrosis factor-alpha blockers, including adalimumab ( Humira), etanercept ( Enbrel), and infliximab ( Remicade). These drugs block a chemical messenger of the immune system called TNF-alpha. People with psoriasis have too much of this substance, which causes inflammation. Ustekinumab ( Stelara). This drug blocks cytokines in the body called interleukin-12 and interleukin-23, which are thought to promote the increased growth rate of skin cells and inflammation from psoriasis. Side effects can include swelling or rash where the shot went in, increased risk for infections including tuberculosis, and cancers such as lymphoma and nonmelanoma skin cancer. You will need to be tested for tuberculosis while taking a biologic drug. You will also need to have regular blood tests to check your number of immune blood cells. 4. Vitamin A Derivatives What it is: A man-made form of vitamin A. How it works: These drugs help control how fast skin cells multiply. There are two types of vitamin A: Acitretin in a pill ( Soriatane) Tazarotene in a cream, gel, or foam ( Avage, Fabior, Tazorac) Side effects can include hair loss; thin nails; dry mouth, eyes, and skin; bleeding gums; nosebleeds; headache; joint or muscle pain; increased levels of fat in the blood; and sensitivity to sunlight. Women who are pregnant or planning on becoming pregnant should not use these drugs due to serious birth defect risks. 5. Apremilast ( Otezla) What it is: An oral drug approved to treat psoriatic arthritis and plaque psoriasis in adults. How it works: Apremilast is an inhibitor of phosphodiesterase-4 ( PDE-4), which controls inflammation within a cell. Side effects include diarrhea, nausea, and headache. These side effects may stop with continued treatment. In studies, a small number of people stopped taking Apremilast because of an adverse reaction. Some participants also had unexplained weight loss. It's recommended that those taking the drug have their weight checked regularly and be monitored for depression. 6. Other Immunosuppressives There are a few drugs that slow down the immune response and may be used in selected cases, but are used âoff-labelâ ( They are not FDA approved for psoriasis or psoriatic arthritis). They include azathioprine, hydroxyurea, and 6-thioguanine.