Urushiol is the reason for those itchy rashes one gets when coming into contact with one of these plants. The oil is found in the leaves, roots, and twigs of poison ivy and its cousins. There is no difference in the rashes, since there is no difference in the cause.

Here are some tips for avoiding the itchy-scratchies:

1. As soon as you suspect that your child is exposed to urushiol, have him wash thoroughly with lots of warm water and soap (hot water opens the pores, and may transiently increase exposure). Water alone will also work, but not quite as well. If you don't have water, use rubbing alcohol. Don't use a washcloth, since this tends to spread the oil to other patches of skin. Likewise, a shower is much preferable to a bath. Have him rinse thoroughly.
   
   
2. If the oil is removed within 5-10 minutes, you may prevent, or at least minimize, the rash. Even if he doesn't wash for a long time, washing is still very important. The oil remains on the skin until it is rubbed or washed off. It can cause a new reaction wherever it touches.
   
   
3. Anything that your child has touched between his exposure and a thorough shower should be washed in soap and water (preferably hot), hosed down, or soaked in water and alcohol. This includes clothing, shoes, balls, toys, tools, and the towel he used after his shower.
   
   
4. After washing the contaminated articles, don't forget to wash your own hands, and anything those articles touched.
   
   
5. Once the oil has been removed, the rash from poison oak or poison ivy is not contagious. Even the oozing blisters are not contagious, although they look like they should be.
   
   
6. As long as the oil is no longer present, scratching does not make the rash spread. Scratching does make the already intense itching even more unbearable and can also cause the rash to get infected.
   
   
7. The best way to prevent an outbreak of poison oak is to avoid any contact with the oil in the first place. Teach your children to recognize the poisonous plants of your region.
   
   
8. Before an outing where you are concerned about these plants, you might want to coat your child's skin with a barrier cream. Hollister Moisture Barrier, Hydropil, IvyBlock and Stoko-Gard Outdoor Cream are all fairly good at protecting the skin from the oil, but must be reapplied hourly to remain effective.
   
   
9. The last tip for prevention -- don't forget to hose down the dog!