If your family enjoys time in the woods while hiking or camping, you may have been affected by the rash caused by poison ivy, poison oak or poison sumac. This itchy allergic reaction is caused by exposure to oils found on plants in the Genus Toxicodendron.
The allergenic compound found in these plans is called urushiol. Interestingly the same substance is also found in ginko fruit and mango peels. This colorless oil is found in all parts of the plant. When it is exposed to the air, it may turn black, causing spots to appear on the leaves. It is estimated that after contact with urushiol, nearly 50% of exposed persons will develop an allergic reaction.
The rash associated with exposure to urushiol is often called ‘poison ivy dermatitis’. The rash develops anywhere between 4 hours and 4 days. The rash is intensely itchy, red, somewhat swollen and generally has fluid-filled blisters that present as lines or streaks. The rash can appear on different parts of the body at different times. This does not mean that the poison ivy is ‘spreading’. Remember that poison ivy is not contagious; you cannot pass it from one person to another. However, the oils from the plant can be carried on clothing, on garden tools, under fingernails or even on pets. Therefore, other family members can develop dermatitis, particularly if they are sensitized to urushiol, without ever coming in direct contact with the plant.
Teach your children to recognize plants in the Toxicodendron family. Remember the age old adage “leaves of three — let them be”. Poison ivy is a vine that either climbs vertically or spreads out through grasses. In the summer, leaves are green, while the plant may have red leaves and white berries in autumn. It is found in wooded areas, but also along rivers, lakes and ocean beaches. Even dead plants can cause an allergic reaction. Poison oak, while less common in Virginia, has leaves that resemble oak leaves. There are three leaflets, but sometimes up to seven in each leaf group. Poison sumac, more common in swampy areas such as Florida, grows as a shrub or small tree with 7 to 13 leaflets on each stem.
While being familiar and avoiding contact with the plants is great protection, it is important to take further precautions, particularly when hiking or doing yard work. Long sleeves, long pants or tall socks provide a layer of protection between the oils and your skin. Heavy vinyl gloves are recommended for yard work that involves handling brush. Remember to remove and wash any clothes that may have had contact with the plant as soon as possible. Washing with mild soap and water within 4 hours of exposure may prevent the rash from developing. Be sure not to scrub the skin, as this may make the skin irritated and more susceptible to rash. Barrier creams such as IvyBlock™ are controversial as to their effectiveness. They leave a clay compound on the skin and must be applied every 4 hours.
Once the rash appears, there are many home treatments that will ease the itching and discomfort. Soaking affected skin in oatmeal baths or the use of cool, wet compresses may provide temporary relief. Lotions containing menthol or phenol (calamine) may help when applied to the rash. Antihistamines taken orally may not provide much relief from the itching, since the itch from poison ivy is not due to histamine. These medicines may sometimes be used if the itching is interfering with sleep, since the most common side effect of antihistamines is drowsiness. Avoid the use of topical antihistamine creams, products intended to numb the skin such as benzocaine, or topical antibiotic ointments. These all have little benefit and may have concerning side effects.
The use of topical corticosteroids may be helpful in easing the inflammation and itching that accompanies the rash. These are products available over the counter such as topical hydrocortisone 1% (Cortaid™). Using this medication as an ointment preparation may feel better on the skin than a cream.
If the rash oozes pus, if face or genital areas are affected, if you have a lot of swelling, or if the rash isn’t improving after 2 to 3 weeks, it is time to contact our office for further treatment. We will evaluate for signs of infection and prescribe oral antibiotics if needed. We may also treat the more severe dermatitis with oral steroids. It is important to remember, however, that most cases of poison ivy dermatitis do not require the use of oral steroids, which have some unpleasant side effects themselves. For severe cases, steroids are tapered over two to three weeks. It is possible to experience resurgence in the rash, known as ‘rebound dermatitis’ with shorter courses of steroids.
If your family is educated, takes protective actions and knows what to do immediately after accidental exposure, hopefully no one will suffer from the itchy consequences of urushiol this summer!