Coming into contact with poison ivy, oak, or sumac may really put a damper on your enjoyment of the summertime. Between 50% and 85% of people are allergic to these plants and will develop an extremely itchy, red skin rash with bumps and blisters wherever the oils from the leaves have touched their skin. The rash is called contact dermatitis because it is an inflammatory response of the skin that occurs when it has come in contact with an allergen (a substance that may induce an allergic reaction).

Preventing the Rash

As soon as you realize that you may have come in contact with one of these plants, thoroughly wash the area with soap and water. It takes 10-20 minutes for the oils of the plants to seep into the skin. It is these oils that cause the characteristic rash, which will spread to wherever the oils touch your skin. Therefore, if you wash immediately, you may be able to avoid a skin reaction.

Oils may also be on clothes, under fingernails, and on the fur of pets who accompany you on your summertime walks. In fact, the sticky resin (called urushiol) of poison ivy, oak, and sumac (all members of the toxicodendron plant genus), can linger on clothes and shoes for a long time. So remove them as soon as possible and run them through the washing machine.

Use a good nailbrush to carefully clean underneath fingernails and then throw the nailbrush away. If you are camping, bring along a few inexpensive nailbrushes. Contrary to popular belief, the rash does not spread from the act of scratching or from the fluid in the blisters. But, if the oils are stuck under your fingernails, the rash can be spread wherever you scratch with those nails. (People are more likely to be scratching the sensitive areas and therefore connect the spread of the rash with the scratching of those areas.)

Finally, get your pet into a bath or shower and scrub him or her down with soap. (Jumping in the lake or ocean may not be enough to remove all of the oils.) It's a good idea to wear disposable gloves while you do this. Animals generally don't get a skin reaction from the resins, but you may get it from petting them.

Often, it is difficult to accomplish what I just described in a short time frame. But even if you are unable to avoid the skin reaction altogether, taking the steps described above will help decrease the likelihood of spread.

Treating the Rash

Once the rash has set in, the three main goals of treatment are to stop the itching, decrease inflammation, and prevent infection.

Alleviating the itch lessens the amount of scratching, which, in turn, lessens the likelihood of developing an infection. In other words, if you scratch a lot, you may break the skin. This allows the bacteria that normally live quietly on the surface of your skin to move inside, where they can cause an infection in the tissue just beneath the skin.

Signs of infection include increased redness, tenderness, and/or swelling in the affected area, greenish or yellowish (rather than clear) fluid oozing from the blisters, and a funny odor. If you suspect infection, contact your doctor right away.

Conventional Wisdom

Doctors and pharmacists generally recommend the following:

Nonprescription Options:

  • Cool compresses with Burow's solution to decrease inflammation and relieve itching
  • Calamine lotion to dry out the affected area and alleviate itching
  • Baths with oatmeal or baking soda to ease the itch

Prescription Options:

  • Oral antihistamines to lessen the itching
  • Topical corticosteroid cream or ointment to diminish inflammation and itching
  • Oral corticosteroids , for severe cases involving a large area, the face, around the eyes, or the genitals


The following herbs have traditionally been used to alleviate skin inflammation and itching. However there is no scientific evidence to indicate that they are safe or effective.

  • Witch hazel ( Hamamelis virginiana ) applied to the skin
  • Oat straw ( Avena sativa ) added to a tepid bath
  • Peppermint oil ointment containing 5% to 20% of the essential oil applied to the skin lesions one to two times per day

Protecting Your Skin

Here are a couple of additional things to bear in mind in your attempts to dodge these aggravating plants or your quest to treat the rash appropriately once it has developed:

Follow the "rule of three"--keep away from any shrubs or vines with leaves of three; these may be either poison ivy or poison oak, often seen in a sudden area of clearing. All three plants also grow berries in the early fall.

  • If you are exposed to the smoke of toxicodendron from the burning of these plants (usually an accidental inclusion of poison sumac in a campfire), you may experience itchy, watery eyes, and even shortness of breath. These symptoms require immediate medical attention.
  • If you have a large area of involvement (20% or more of your body surface area) or if eyes, face, or genitals are affected, or if there are signs of infection, see your doctor as soon as possible.