Does Your Rash Itch?

Psoriasis is a chronic skin disorder that is caused by changes in certain immune system cells that make them "fight" normal skin.

Psoriasis produces thick, silvery scales on a red base that has a distinct border. It's commonly found on the knees, elbows, and scalp.

Pityriasis rosea is a common rash that has a striking appearance. It starts with a "herald patch" -- a single, round/oval lesion that often occurs on the trunk. The rash then spreads along skin lines on the trunk. The rash is very itchy and lasts for 6 to 8 weeks.

Poison ivy, or rhus dermatitis, is caused by exposure to a resin called urushiol found on certain plants of the Rhus genus. These plants include poison ivy, oak, and sumac.

This well-known rash starts out with blisters and redness on the exposed areas that spread on contact with the blisters. Poison ivy and other forms of irritant contact dermatitis are treated with topical steroids.

Chicken pox is a very itchy rash caused by the varicella virus. Since the development of a chicken pox vaccine, we don't see as much chicken pox in the United States compared to twenty years ago.

See the classic chicken pox rash (it looks like a "dew drop on a rose petal") and other chicken pox pictures.

Pregnant women with chicken pox may need treatment with special medications. Anyone who has been exposed to chicken pox (even if they were immunized) is at risk for developing shingles later in life.

Scabies is a rash caused by a tiny mite that burrows under the skin. The rash is red, bumpy, and often located on wrists, between fingers, in armpits, and around the waistline. Scabies is treated with a lotion to kill the mite, but the rash can last up to a month.

Eczema is an itchy rash that is closely related to allergies. It is also known as "the itch that rashes."

The exact cause of eczema is not known, but it seems to be related to abnormalities in the epidermis that make the skin drier than normal and more sensitive to common chemicals.

Eczema is diagnosed based on the presence of major and minor criteria. There is no cure for eczema, but its symptoms can be managed by lifestyle changes and medications.

Hives (urticaria) is a rash that can evolve and change in hours -- even minutes.

Hives are actually divided into acute hives (lasting less than 6 weeks) and chronic hives (lasting longer than 6 weeks). This distinction is important because chronic hives actually have some strange causes like pressure or water-contact.

The factors that can cause hives are numerous, and we often can't isolate one. The good news is that there are medications that can treat hives effectively.

Ringworm is a fungal infection that typically occurs on the body. The rash is typically round, red, raised, and scaly on the outside of the lesion. Ringworm can be effectively treated with oral or topical medications.

Athlete's foot is a fungal infection that causes redness and scaling between the toes. Athlete's foot is treated with topical antifungal medications.