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Poison Ivy
Does the thought of poison ivy make you itch just thinking about it? That is exactly what I feel anytime I think about poison ivy. It is the kind of itch that is so bad you can’t sleep at night. Poison ivy makes its appearance frequently during the “outdoor months” in urgent care and emergency departments throughout the United States. It is important to be able to recognize poison ivy and other poisonous plants and differentiate these from other common contact dermatoses. It is also important to know how to manage this condition and educate patients about how to avoid this and other skin irritants in nature.
The best scenario is one in which the patient doesn’t come into contact with poison ivy and as a result never develops symptoms. There is a group of plants that produce an oil called urushiol. The Urushiol oil is responsible for the itching rash. The oil is released when parts of the plant such as the leaves damaged. This damage is what allows for the release of the oil. It only takes 50 mcg of this oil to cause a rash in over 80 percent of adults. While most patients will commonly refer to their exposure as a poison ivy rash, there are actually 3 different plants that can cause a similar rash from urushiol oil. These three plants include poison ivy, poison oak, and poison sumac.
Pick Your Poison
Poison ivy is found throughout the United States, with the exception of Alaska and Hawaii. The US west coast and southeastern US are home to poison oak exposures. Poison sumac is primarily found east of the Mississippi River, Minnesota, Texas, and Louisiana. There is the common saying of “leaves of three, let it be”. For the most part, this is true and an easy saying to remember. Poison ivy and poison oak both typically have the leaves of three. Both poison ivy and oak are found in shrubs and vine-like arrangements. This also depends on location in the United States. Poison sumac is the outlier of the group and has a shrub with stems that contain 7-13 paired leaves. The contact with these plants is the most common means of transmission of the oil.
Inhalation and Exposure
Patient history should address if plants were burned or smoked (people do crazy things!). Inhaled urushiol can cause significant lung irritation. Urushiol exposure causes a fairly typical rash in the more than 80% of the adult population that have a reaction to it. It does not develop immediately after exposure, which is why it is sometimes hard to pinpoint the exact cause of the rash. Patients come in with a rash and were working outside a few days prior, but usually don’t remember coming into contact with a poisonous plant. Most commonly, this is due to the fact that they don’t know what poison ivy, poison oak, or poison sumac look like. If they knew what to look for in these plants, they would have most likely avoided contact with them.
Rash
Many patients who have a “rash” may have contact dermatitis. However, in these cases the exact irritant may never be known and doesn’t change the treatment plan. In the case of urushiol exposure, the rash will present differently than another contact dermatitis rash. Urushiol exposure will appear erythematous with small bumps and often have blisters. There will be an intense itching associated with the rash. Another unique finding specific to urushiol exposure is that the rash develops as varying times. A patient may have a rash appear on their face, the next day on their hands, then the following day on the soles of their feet. The patient usually thinks this is because the rash is “spreading”. It is important to remember that the rash cannot spread once the oil is washed off the body and clothes.
The rash itself is not contagious. The development of the rash depends on the thickness of the skin at each location. It also relies on the absorption of the urushiol. In areas with thinner skin, i.e. the face, the rash will appear sooner than areas that thicker skin, i.e. soles of the feet.
Management
The first step with exposure to urushiol is removal of the oil from the patient. Urushiol is an oil so it is difficult to remove with regular soap and water. Dishwashing detergent or rubbing alcohol are great alternatives to hand soap for the removal of the oil. In the removal of oil, you have to make sure to also wash underneath the patient’s nails with a brush, as oil can often become trapped there. Trapped oil underneath the nails can easily spread to other parts of the body by simple contact. Wash all exposed clothing, blankets, hats, etc. with detergent and hot water.
Home Remedies
After the initial period of exposure, the patient has most likely already showered and it will be hours or days later when they present to the clinic. This is when the itching becomes unbearable and they are looking for any relief possible. Common treatments already tried at home may include cold compresses, calamine lotion, and oatmeal baths. If these haven’t yet been tried, they may provide minimal itch relief to the patient. Burrow’s solution is another home remedy that can help dry up the weeping fluid from the blisters. Antihistamines do not have a role In treatment. They will not help with the itching because urushiol does not trigger the release of histamine.
Steroids
Topical steroids can help, but are most beneficial in the first few days after exposure. Orals steroids are useful. The recommended length of treatment is 14 to 21 days with a taper. Shorter courses will likely result in Incomplete treatment and a recurrence of swelling and itching.
Antibiotics
Secondary infections should be treated with oral antibiotics. There is no primary role for antibiotics in initial management.
Patient Education
The patient should be educated about how to avoid future exposures to poison ivy, oak, or sumac. Prevention is the best case scenario when it comes to urushiol. Review with patients that making sure to wear garments that protect exposed skin, like long sleeves, boots, long pants, gloves, socks. Remove and wash exposed clothing after working outdoors. Clean outdoor tools with rubbing alcohol or copious amount of water and dishwashing soap. This is an important step because urushiol can remain on surfaces for up to 5 years. Barrier creams like bentoquatum may limit oil absorption. These creams must be washed off and reapplied frequently (twice a day at the minimum). Animals and pets can also be exposed and should be washed as well.
Poison ivy is a clinical diagnosis. It can be successfully managed with both over-the-counter and prescription medications. The biggest impact a clinician can have for these patients is through education. Education about the management of symptoms and course of the rash is necessary, along with education on how to prevent future exposures.
References:
National Institute for Occupational Safety and Health. (2018). Poisonous Plants. Retrieved from
https://www.cdc.gov/niosh/topics/plants/default.html.
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