The rash usually appears 8 to 48 hours after your contact with the urushiol. But it can occur from 5 hours to 15 days after touching the plant.1 The rash usually takes more than a week to show up the first time you get urushiol on your skin. But the rash develops much more quickly (within 1 to 2 days) after later contacts. The rash will continue to develop in new areas over several days but only on the parts of your skin that had contact with the urushiol or those parts where the urushiol was spread by touching.
The rash is not contagious. You cannot catch or spread a rash after it appears, even if you touch it or the blister fluid, because the urushiol will already be absorbed or washed off the skin. The rash may seem to be spreading. But either it is still developing from earlier contact or you have touched something that still has urushiol on it.
The more urushiol you come in contact with, the more severe your skin reaction. Severe reactions to smaller amounts of urushiol also may occur in people who are highly sensitive to urushiol. Serious symptoms may include:
Without treatment, the rash usually lasts about 10 days to 3 weeks. But in people who are very sensitive to urushiol, the rash may take up to 6 weeks to heal.
A frequent complication of the rash is infection. If this occurs, your doctor will probably prescribe an antibiotic cream that you spread on the affected skin if the infection is small. Otherwise, you may need antibiotic pills or a shot. To prevent infection, try not to scratch the rash. Cut your fingernails short to minimize the possibility of opening the skin and spreading bacteria.
Regardless of what type of treatment is used after a rash develops, the length of time it lasts will vary from person to person.
If you suspect that your skin has touched poison ivy, oak, or sumac, wash the area to help prevent a reaction. Clothing and other items that may have oil on them should be thoroughly washed right away too.
You may be able to use a product that dissolves urushiol, such as Tecnu or Zanfel. These products are used to wash the oil off your skin or other objects. They may reduce the severity of a reaction or prevent one.
The most common complication of poison ivy, oak, or sumac rash is a secondary infection, usually caused by scratching. When this occurs, your doctor will probably prescribe a type of topical antibiotic cream if the infection is in a small area. Otherwise, you may need systemic antibiotics, given as pills or shots.