What are the symptoms of poison ivy, oak, or sumac?

The most common symptoms of the rash (allergic contact dermatitis ) from poison ivy, oak or sumac are:

• Itching.
• Red streaks or general redness where the plant brushed against the skin.
• Small bumps or larger raised areas (hives).
• Blisters filled with fluid that may leak out. In rare cases, some people develop blood-filled blisters that can turn black and become shiny dark spots.

The rash may have several stages, and its severity can also vary. It usually appears 8 to 48 hours after you have contact with the plant oil (urushiol). But it may occur up to 15 days after the contact. The rash will continue to develop in new areas over several days but only on the parts of the skin that first had contact with the plant oil or those parts where the oil was spread by touching. Blister fluid cannot spread the rash. Areas where the skin is thick, such as the soles of the feet and the palms of the hands, are less sensitive to the oil.

People who are highly allergic to the urushiol in these plants can have more serious symptoms that may need medical treatment. Serious symptoms may 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.

Other conditions with similar symptoms - Other kinds of plant rashes can look like a poison ivy, oak or sumac rash. These include rashes caused by:

• Other plants, such as the ginkgo tree, which contain urushiol or a similar oil.
• Irritant plants, such as stinging nettle. These rashes are not caused by allergic reactions.
• Phytophotodermatitis, which may happen when you touch certain plants and then go into the sun.

Skin conditions that may look like the rash from poison ivy, oak or sumac include:

• Scabies, an itchy skin condition caused by mites.
• Shingles (herpes zoster), a viral skin infection.
• Impetigo, a bacterial infection of the skin.

Insect bites, exposure to nickel and other metals and exposure to chemicals found in fabrics, lotions or laundry detergent may also result in a similar skin rash.