Medicine you apply directly to your nails are often called "topical" drugs. For nail psoriasis, your doctor may suggest a corticosteroid (such as clobetasol), vitamin D, or retinoid creams that you rub into your nail and cuticle every day.
If your nails are thick, the medicine you apply may have a hard time getting inside. Gels or ointments that contain urea can help thin them.
Your doctor may also prescribe a nail lacquer that hydrates and strengthens your nails. You apply it every day in the same way you put on nail polish.