Corticosteroids and poison ivy, oak, or sumac rash

High-dose prescription corticosteroid medicines can reduce the symptoms of a poison ivy, oak, or sumac rash (allergic contact dermatitis) and sometimes reduce the severity and shorten the length of a rash. These medicines are usually used only for more severe cases of the rash, such as when it covers about 10% of the body's skin or when the face, hands, and genitals are affected. Prescription corticosteroids are available as pills, creams, gels, ointments, or shots.

• Corticosteroid pills (usually prednisone) can dramatically reduce the symptoms caused by a strong reaction to poison ivy, oak, or sumac. Oral corticosteroids generally are more effective than other forms of these medicines for poison ivy, oak, or sumac and are usually taken until the symptoms are gone. How much medicine you take and for how long often depends on how soon you seek help after the rash appears.
• Creams, gels, and ointments applied to the skin may help reduce itching and redness. These types of corticosteroids have no effect on blisters but may be useful after blisters have disappeared.¹ They should be used for the recommended amount of time, because the rash can reappear if they are stopped too soon. None of these products should be used on the face or genitals because they can cause the skin to become thin and fragile.
• Shots of triamcinolone diacetate are sometimes used when you cannot take corticosteroid pills. Improperly injected corticosteroids can discolor the skin and cause scarring.

Prolonged use of oral and injected corticosteroids can cause serious side effects, such as thinning of the bones (osteopenia), slowed growth in children, and increased risk of an ulcer or infection. Talk with your health professional about your risks when using these medicines.

High-dose corticosteroids should not be confused with over-the-counter hydrocortisone creams, gels, or ointments, which may soothe itching in mild cases of poison ivy, oak, or sumac rash. These products are not recommended for severe rashes because they are not strong enough and may not be used long enough to work. They may appear to work for a time, but the rash often suddenly flares up again, sometimes worse than before.

Citations

1. Peate WF (2002). Occupational skin disease. American Family Physician, 66(6): 1025–1032.