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What is the best treatment for a poison ivy rash?

Medically reviewed by C. Fookes, BPharm. Last updated on Sep 4, 2019.

Official Answer

by Drugs.com

Poison ivy (botanical name Toxicodendron radicans) is a plant that grows almost everywhere in the United States. The sap of the poison ivy plant contains an oil called urushiol which causes an allergic reaction and rash within 12 to 48 hours in 85% of people it contacts. Contact with the oil doesn’t have to be direct either, it can linger on clothes, gardening equipment, shoes, sports gear, and pets and cause a reaction days or weeks later.

The rash caused by poison ivy is a type of allergic contact dermatitis and starts within 12 hours of contact but may take a few days to fully develop. Typical symptoms include:

  • Intense redness
  • Itching
  • Multiple, painful blisters
  • Swelling
  • Thin red lines of rash reflecting direct contact with the edges of the leaves.

The rash typically just covers the area of skin that came into contact with the oil; however, it may be more widespread if caused by pets rubbing against you that have oil on their fur or if lawn clippings contaminated with poison ivy are touched when emptying the mower bag.

The severity of the reaction decreases with age, especially in people who have been exposed to the plant in the past. The rash will usually get better within a couple of weeks, even without treatment.

Most cases do not need to be treated by a doctor; however, you should go to the emergency room if you have shortness of breath, trouble swallowing, the rash is on your face or genitals, covers a large area of your body, or if there is swelling. Widespread rashes may require treatment with a prescription corticosteroid.

If you come into contact with poison ivy you should:

  • Immediately wash all areas of skin and your clothes that have touched the plant
  • Take an over-the-counter antihistamine
  • Apply calamine lotion or hydrocortisone cream to stop the itching
  • Don’t scratch – this will just prolong your symptoms and increase your risk of developing a bacterial infection
  • Apply cool, wet compresses to soothe the itch or take frequent colloidal oatmeal baths
  • Consider other remedies such as aloe vera, apple cider vinegar, or witch hazel.

How do you treat a poison ivy rash?

Most cases of poison ivy don’t need to be treated by a doctor; however, widespread poison ivy rashes may require treatment with a prescription corticosteroid. Rarely, you can also develop a bacterial infection at the rash site. If this happens, you may need a prescription antibiotic.

Corticosteroids for poison ivy

Prescription corticosteroids are usually only prescribed to treat poison ivy rash if the rash covers more than 10% of the skin or if the face, hands or genital are involved.

Corticosteroids are available as oral tablets, topical preparations (creams/ointments) or injections.

Oral tablets (usually prednisone) dramatically reduce symptoms in people who have a severe reaction to poison ivy and are usually prescribed short-term. Prolonged use can cause bone changes, skin thinning, an increased risk of infection and stomach ulcers.

Topical corticosteroids include clobetasol, betamethasone, or triamcinolone may help reduce itching and redness. They don’t usually have an effect on blisters. They should be used exactly as your doctor has directed because the rash can reappear if they are stopped too soon. Strong corticosteroid creams are not usually prescribed for use on the face or genitals because they can cause the skin to become thin and fragile.

Over-the-counter hydrocortisone creams are not as strong as the topical corticosteroids doctors can prescribe and are not recommended for severe rashes because they are not strong enough. Although they may appear to work for a short period of time, the rash may suddenly flare up, worse than before.

Corticosteroid injections may be used in people with a severe reaction who cannot take oral tablets.

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