In one sentence, describe what the following article is about:

In addition to topical treatments, your doctor may prescribe an oral or injected medication, especially if your psoriasis is severe. One commonly prescribed medication for psoriasis is methotrexate. This is an anti-inflammatory medication that is taken either in pill form or as an injection. Most patients take it weekly in tablet form.  Do not use methotrexate if you are pregnant or trying to conceive. Methotrexate can seriously harm a developing fetus, and can also damage sperm cells. Long-term use of methotrexate can damage your liver. Do not use methotrexate if you have liver disease, and never use it in combination with alcohol. This is a drug that suppresses the immune system and reduces the inflammation associated with psoriasis. It is usually taken daily in pill form. Cyclosporine can cause kidney damage and may increase your risk of infectious diseases and cancer. It should only be taken under your doctor's close supervision, over a relatively short period of time. Your blood pressure and kidney function should be monitored while you are on this medication. Oral retinoids, like acitretin, may be effective against severe psoriasis that does not respond to other types of treatment. However, retinoids can cause unpleasant side effects, such as cracked and inflamed lips, hair loss, or (in rare cases) liver damage. They are also extremely harmful to a developing fetus.  If you are planning to become pregnant, you must wait at least three years after taking an oral retinoid before trying to conceive. Oral retinoids have not been shown to cause mutations in sperm cells, so it is safe to try to father a child while taking retinoids. These medications are made from natural materials, such as plants or microorganisms, and are sometimes known as biological response modifiers or targeted therapies. They interact with specific parts of the immune system, stopping it from attacking the skin and causing inflammation. While these medications can be effective against severe or stubborn psoriasis, they can also put you at serious risk for developing life-threatening infections. Some common biologic agents that are prescribed for facial psoriasis include:  Infliximab (Remicade) Etanercept (Enbrel) Adalimumab (Humira) Ustekinumab (Stelara) Secukinumab (Cosentxy)

Summary:
Treat psoriasis with methotrexate. Take cyclosporin. Use an oral retinoid medication for severe psoriasis. Take a biologic agent.