Moderate to severe psoriasis may be treated with phototherapy, or exposure to light, that is carefully prescribed by the healthcare provider. Possible options include:

• PUVA photochemotherapy, which uses a light-sensitizing medicine known as methoxsalen together with ultraviolet A light
• sunlight
• ultraviolet B irradiation along with one or more topical medicines

Severe psoriasis is often treated with the following oral medicines:

• cyclosporine
• methotrexate 
• retinoids, such as isotretinoin and acitretin

Isolated patches of psoriasis that are resistant to other therapy may be injected with triamcinolone acetonide.

What are the side effects of the treatments for psoriasis?

Side effects of steroid creams and ointments include thinning of the skin and stretch marks. Coal tar can make the person sensitive to ultraviolet light. Anthralin and vitamin-based products can irritate the skin.

Phototherapy increases a person's chance of developing skin cancer or premature aging of the skin. Retinoids can cause birth defects if taken by a pregnant woman. Methotrexate can damage the liver, while cyclosporine can damage the kidneys.

What happens after treatment for psoriasis?

Psoriasis should clear substantially with appropriate treatment, although this varies from person to person. Treatment of psoriasis is lifelong.

How is psoriasis monitored?

Any new or worsening symptoms should be reported to the healthcare provider.