Your doctor may have decided that a systemic treatment could do more to relieve your symptoms than your creams. Systemic drugs are given by injection or taken by mouth and work throughout the whole body.
Systemic treatments such as Ilumya are generally more effective at improving psoriasis symptoms than topical treatments (drugs applied to the skin). This is because they work from the inside out. They target the immune system itself, which causes your psoriasis plaques. This can help both clear and prevent psoriasis plaques.
Topical treatments, on the other hand, generally treat the plaques after they’re formed.
Systemic treatments are sometimes used in combination with, or instead of, topical treatments. They may be used if:
topical medications don’t improve your plaque psoriasis symptoms enough, or
plaques cover a large portion of your skin (typically 3 percent or more), making topical treatments impractical. This is considered moderate to severe psoriasis.