Poison ivy, oak and sumac are the leading culprits behind of allergic skin reactions in the United States — with an estimated 55 million occurrences each year. If you’re in the 70 percent or so of the population who is sensitive to this oil — a colorless, odorless resin called urushiol — you may know well the end result: an itchy rash with oozing blisters.
DETECTING THE SYMPTOMS
The rash from poison ivy/poison oak (Rhus dermatitis) can develop anywhere from 30 minutes to five days after the exposure, and can last anywhere from 10 days to three weeks. The timing and severity of the outbreak depends on how sensitive you are, how much contact was made with the poison plant, where exactly on your skin you were exposed, and if you’ve had a reaction before. (It may take more than a week to show up the first time you come in contact with the plant’s oil, but it tends to develop more quickly with each outbreak.)
“The allergic reaction from poison ivy is caused by oil in the plant,” says Lisa Hammer, MD, a pediatrician at the University of Michigan CS Mott Children’s Hospital. “The reaction usually starts with redness and swelling of the skin, which is then followed by either bumps or blisters.”
The initial symptoms of poison oak/poison ivy include:
- Itchy skin, red streaks or overall redness where the plant brushed against your skin.
- A rash, small bumps or bigger hives (larger raised areas).
- Blisters filled with fluid which may seep/leak.
More serious symptoms include:
- Swelling of the face, mouth, neck, genitals or eyelids (which may prevent the eyes from opening).
- Widespread, large blisters that ooze large amounts of fluid.
Keep in mind that the rash can develop in new areas over several days (though this nearly always does not mean that the oils have spread — just that the urushiol is taking its time).