AUSTIN, Texas — Think of it as the cockroach of the weed world.

Poison ivy thrives in the extreme heat and drought and spreads through the most casual of contact. It can seem impossible to eradicate.

Urushiol oil is present in all parts of the poison ivy plant, and most people will develop an itchy, blistering rash when coming into contact with it.

This rash might not develop until 12 to 24 hours after contact, according to the American Academy of Dermatology.

A lot of people get it by using gas or electric trimmers, says Trisha Shirey, director of Flora & Fauna at Lake Austin Spa Resort.

What to do immediately after exposure

If you do notice that you’ve been exposed to the vine (its leaves grow in clusters of three, and it sprouts green-yellow flowers in the spring), there are some immediate steps you can take:

• Rinse your skin with lukewarm water.

• Wash tools and any clothing that might have come in contact with the vine.

What to do after rash develops

Once a rash has developed, there are ways to ease your suffering (which can last for several weeks).

Don’t worry about scratching the rash and then transferring it to other parts of your body. Once a rash has developed, that can’t happen.

The AAD recommends oatmeal or baking soda baths, calamine lotion, cool showers and compresses, and oral antihistamines to relieve the intense itching.

Shirey uses Tecnu ( www.teclabsinc.com ), a skin cleanser formulated to remove urushiol after exposure but before a rash develops. But when the cleanser is not enough, she adds a white or green clay facial mask. She mixes the clay with water, applies it to the rash, allows it to dry, rinses it with cool water and repeats until the redness and irritation are gone.

How to get rid of the weed

Getting rid of the noxious weed is tough, Shirey says. The key is to nip the problem in the bud.

“One of the ways it gets transmitted is with birds, so you’ll find young sprouts coming up here and there, and the best thing to do is to get that sprout out by the root before it has a chance to grow,” Shirey says.