Now that we are in the dog days of summer, an old friend is rearing it’s ugly, leafy head. Yes, it’s poison ivy season, my friends, and while most of us think we know all there is to know about this itch-inducing plant, there are some medical myths lurking around it that need to be busted!
First, the facts: Poison ivy, poison oak, and poison sumac plants are all coated with a colorless oil called urushiol. Urushiol is a very sticky, colorless substance present in the leaves, stems, fruit, and roots of the plant. After contact with urushiol, about half of us will develop intense itching, swelling, and skin redness. Then, we will develop fluid-filled blisters that are often arranged in a line or streak. (See photos) The symptoms are usually most severe within 1 to 14 days after exposure to the plant, but can occur up to 21 days after exposure if someone had never been exposed to urushiol before.
Technically speaking, poison ivy usually resolves within 1-3 weeks without treatment, but without something to control the itching they will be the longest 3 weeks of your life. Cool wet compresses can be placed on the affected areas for 15 to 30 minutes at a time. A group of medications called antihistamines are very good at reducing the itching: diphenydramine (Benadryl) is good for night time because it makes you sleepy and loratadine (Claritin) and cetirizine (Zyrtec) are good for daytime because they don’t. Oatmeal baths, calamine lotion and hydrocortisone cream are also sometimes helpful, but the best way to knock out the rash and itching is to see your primary health care provider to get a prescription steroid treatment. Sometimes you can get by with just a shot, but that often does’t last long enough (1-2 days) so you can take a course of pills over a couple of weeks.
Now, on to the myth…
TRUE OR FALSE: Poison Ivy is contagious
Poison ivy is not contagious and can not be passed from person to person. Only contact with urushiol will cause someone else to get poison ivy – the fluid that leaks from blisters does not contain the oil and can not cause symptoms. Once you’ve washed the urushiol off of your skin (and clothes and fingernails and gardening tools and pets…) you can not spread poison ivy to someone else or yourself. The rash sometimes appears to be “spreading” from one part of the body to another, but this is because blisters develop at different rates in different parts of the body – any real spreading that went on happened before you realized you had the urushiol on your skin. This explains why poison ivy has such an unfortunate predilection for our privates. Please believe me – if you’ve been weeding in the yard, or camping in the woods, make sure you wash your hands before you go to the bathroom as well as after…
John Vaughn, MD – Student Life Student Health Services
Updated by Maribeth Mulholland, MD – Student Life Student Health Services