Poison Ivy, Oak, or Sumac: Relieving the Itch

Topic Overview

A rash caused by poison ivy, oak, or sumac may itch and produce blisters. Try the following suggestions and medicines to help relieve these symptoms.

General suggestions

• Although the rash does not spread through blister fluid, try not to scratch blisters. Scratching may cause a bacterial infection.
• Apply wet compresses or soak the area in cool water for 15 to 30 minutes several times a day. Do this for 1 to 4 days until the itching and blistering improve. Compresses or soaking water may include:
  • Baking soda. Add baking soda to water to make a solution for a wet compress, or mix it with water into a paste and then apply the paste to the rash.
  • Vinegar mixed with water.
• Take short, cool baths with or without an oatmeal additive (such as Aveeno).
• Use as little soap as possible. Use gentle soaps, such as Basis, Cetaphil, Dove, or Oil of Olay. Avoid deodorant soaps when you have the rash.
• Avoid dry skin, which makes the itching caused by the rash worse. Apply a moisturizer or calamine lotion to the skin while it is damp. Watch closely for excessive drying, which may occur when calamine lotion is used for an extended period. For more information, see the topic Dry Skin and Itching.

Medicine

Medicines that relieve itching include:

• Over-the-counter antihistamines, such as a nondrowsy one like loratadine (Claritin) or one that may make you sleepy like diphenhydramine (Benadryl), and prescription antihistamine pills such as hydroxyzine (Vistaril). Talk to your doctor before you use these medicines. And do not drive while taking them. The form of Benadryl you spread on your skin may cause another allergic reaction and should not be used.
• Over-the-counter hydrocortisone products, such as Cortaid, Caldecort, or Lanacort, that you spread on your skin. These products should only be used in mild cases, usually after the affected area has been soaked in water or a compress has been applied. Although safe, these products are not recommended for treating poison ivy, oak, or sumac rash, because they are not strong enough and may not be used long enough to be effective. They may seem to work for a while, but the rash often suddenly flares up again, sometimes worse than before.

Medicines that dry out oozing blisters include:

• Aluminum hydroxide gel.
• Kaolin.
• Zinc acetate, zinc carbonate, or zinc oxide.

If you have a severe rash from poison ivy, oak, or sumac, talk to your doctor. You may need prescription corticosteroids.

Do NOT use the following medicines. They may increase sensitization and/or cause more skin problems:

• Antihistamines applied to the skin, such as diphenhydramine (found in Benadryl cream, spray, or gel). The oral form of Benadryl may be helpful.
• Anesthetics containing benzocaine (such as Lanacane) that are applied to the skin.