Poison Ivy

Poison Ivy

“Leaves of three let them be.”   See photos and video.

Poison ivy is extremely common on the IUB campus, surrounding areas and most of the U.S. The vines grow on trees, rock walls, and buildings. It can even take over small bushes and shrubs. It is recognized it by three vaguely mitten shaped leaflets, all joined to a common stalk. Sometimes, the stems are slightly reddish. In mid-summer, it sprouts grape-like clumps of greenish to off-white berries. In the fall, the leaves can turn an attractive orange-yellow or red...inviting to the touch, but please avoid that temptation! There are two other less common, yet locally found, plants of the same family and genus with similar capability to cause contact dermatitis that that you should be aware of…poison oak and poison sumac. They are different in appearance than poison ivy and less commonly seen in the Bloomington area, but as potent. Learning to identify all three is a worthwhile investment of time.

The "poison" in poison ivy is the allergenic compound urushiol, a light, colorless oil found in the leaves, stems, vines, roots and berries. Touching, bruising, cutting, breaking or burning any part of the plant readily releases the oil, which clings to skin, under fingernails, to pet and animal fur, yard tools, camping gear and clothing. A contact dermatitis rash develops from touching the plant or those items, even weeks later. Inhalation of smoke from burning poison ivy can cause reactions in nasal passages, the oral cavity and the lungs. Since the oil remains on the plant long after the leaves fall off, poison ivy reactions can occur in any season, even during winter. Poison ivy dermatitis affects all ethnicities and skin types.


Approximately 50% of persons who contact poison ivy will develop symptoms. The symptoms vary in severity from person to person. The plant oil can begin to penetrate the skin within 5-10 minutes of contact. Poison ivy rash can appear in as little as 4 hours or as long as 2-3 weeks after exposure. Generally, the first blisters appear within 1-14 days. Symptoms include:

  • Red, swollen, itchy skin with a rash that can be widespread depending on contact areas. Often the rash is streaked or linear in the pattern of contact with the plant.
  • Blisters that break and ooze. The fluid from the blisters does not cause further spread of rash on the body or to others.
  • Secondary skin infection can occur from excessive scratching which will cause pain, increased redness and a potential change in the nature of the drainage from clear to pus like.


The best prevention is to avoid all contact by skin, pets and any item with any part of the plant. Learn to recognize the appearance of poison ivy, poison oak and poison sumac. Avoid walking too closely to discharge from mowers, bush hogs, and weed trimmers. Do not expose skin or lungs to smoke from brush pile fires. Wear protective clothing and heavy vinyl gloves in bushy or wooded area or in contact with outdoor pets. Some benefit with use of commercially prepared barrier creams such as Ivy Block (Bentoquatam) has been documented. Washing with soap and water within 10-20 minutes of exposure may prevent or at least lessen the severity of the rash. Even washing up to one to two hours after exposure may be somewhat helpful. Avoid vigorous scrubbing of skin which can worsen the rash. Use a fingernail brush to remove poison ivy oil left under the nails. Wash clothing and other items in warm soapy water.


Once the itch arrives, further washing to remove the urushiol oil is not likely to help. Keep in mind the itch and rash can occur to any part of the body with which contaminated hands, clothing, pets, etc. have come in contact…yes, even there.

There are a few things to ease that awful itching. Try these tips:

  • Take cool baths and showers, because heat causes the rash to itch and swell more.
  • Cool Domeboro (Burow's) Solution soaks or compresses can be soothing
  • Compounds containing menthol and phenol, such as Calamine Lotion, can temporarily lessen itch
  • Over the counter topical steroids, such as 1% hydrocortisone cream may of benefit. Avoid repeated use to sensitive skin areas of the face, genitalia, or skin fold areas, or any use to mucosal areas or around the eyes. Do not use for more than 14 days.
  • Treat broken blisters with gentle soap and water and, if needed, light non-adherent bandages to prevent infection.
  • Avoid use of topical products containing benzocaine, neomycin, bacitracin, or antihistamines, as they possess their own allergenic potential.
  • Since the itch from poison ivy is not caused by histamine release, second generation antihistamines such as Claritin, Allegra, or Zyrtec are of little use. First generation antihistamines such as Benadryl have some potential for relief, largely through side effects of sedation, which at least allow for sleeping despite the itch. Driving, alcohol and recreational drug use, and use of any other known sedating medications should not be mixed with first generation antihistamines.
  • Consider treatment at the Student Health Center for cases of suspected poison ivy or other types of contact dermatitis. If indicated, prescription medications may help relieve or improve symptoms. Provider health care is recommended for rash near the eyes or covering large areas of the body.

Still haven’t found what you’re looking for?

Remember, reading about a condition is no substitute for getting expert advice from a medical professional. If you have symptoms that worry you, schedule an appointment at the Student Health Center.