Psoriasis which is resistant to topical treatment and phototherapy is treated by medications that are taken internally by pill or injection.
- As a first step, medicated ointments or creams are applied to the skin. This is called topical treatment.
- If topical treatment fails to achieve the desired goal then the next step would be to expose the skin to ultraviolet (UV) radiation. This type of treatment is called phototherapy.
- The third step involves the use of medications which are ingested orally or by injection. This approach is called systemic treatment.
- Over time, psoriasis can become resistant to a specific therapy. Treatments may be periodically changed to prevent resistance developing (tachyphylaxis) and to reduce the chance of adverse reactions occurring. This is called treatment rotation.