Your skin might be more sensitive in the breakout area, so it might be a common sense good idea to keep it protected from sunlight. But it doesn't make it spread. Urushiol is the powerful antigen that causes a reaction in 60-80% of all exposed to it. The Urushiol binds to cell membrances with fifteen minutes and causes the skin eruptions we're accustomed to seeing. Nasty stuff. One will have an initial outbreak, then often, in a day or two, it begins to spread. This spreading is an indication of LESS urushiol having been deposited in those areas...not from scratching, the sun, or anything else. Here's more information: poisonivy.aesir.com
Just FYI, if one knows they've been exposed and can wash with soapy water within 15 minutes, outbreaks can often be avoided.
Just FYI, if one knows they've been exposed and can wash with soapy water within 15 minutes, outbreaks can often be avoided.