How to diagnose a red itchy skin rash

Updated February 21, 2017

If you are suffering from a red, itchy skin rash, you will need to find out whether it is caused by a virus, infection of the skin or an allergic reaction to some pathogen before you decide how to treat the condition. Be sure to notify your doctor if your symptoms do not improve within five days or if you develop other symptoms along with the dermatological ones. While skin rashes may cause temporary discomfort, some rashes may be indicative of a more serious illness that will require medical intervention.


Hives are itchy red bumps that form in patterns, last a brief period of time and are usually located in a specific area of the body, rather than all over your skin. Hives may be caused by a number of irritants or conditions, including clothing, detergent, soap, insect bites or as a manifestation of nervousness. They can be very small--about the size of a pencil eraser--or very large, and they may combine with other hives to form itchy or scaly plaques on the skin. Usually, hives only last a day or two and then disappear untreated. They are thought to be caused by a release of excess histamine in the bloodstream. Over-the-counter creams are usually sufficient to treat the discomfort of acute hives.


Skin infections, or other infections in the body, may cause red, itching or swollen areas on the skin. An example of a skin infection is ringworm, which is caused by a fungus and leaves doughnut-shaped itchy patches with a yellowish, patchy centre on the skin. Athlete's foot is another type of skin infection caused by a fungus. It causes scaling, itching, and red or white patches between the toes. Infections of the skin are usually treated with an antibiotic or anti-fungal cream prescribed by a dermatologist or purchased over-the-counter at a pharmacy. Unlike viral skin conditions, they are generally located in one or two areas on the body, instead of all over.


Eczema is characterised by large, itchy and scaly areas of plaque or dry skin that may become infected and unsightly when scratched. It is thought to be caused by a sensitivity to environmental pollutants, such as chemicals or enzymes in foods and cleaning products. While there is no cure for eczema, it can be treated with topical steroid creams that help to relieve the discomfort and heal the skin. Keeping the skin moist will also help to inhibit breakouts of eczema.


Chickenpox are small, red, itchy raised spots all over the body and are caused by the highly contagious varicella-roster virus. Each spot usually contains a tiny dot of pus, known as a "dewdrop," and may scale over with a dry, yellow patch after a few days of infection. While uncommon in the United States, due to mandatory vaccinations for school-age children, chickenpox have recently become more prevalent and can be easily spread from person to person. It is possible for a vaccinated person to have an outbreak of chickenpox or shingles, another skin condition caused by the varicella virus that occurs in people who have already had chickenpox.


Shingles occur in people that have already had an episode of chickenpox in their lifetime. It is caused by the varicella-roster virus and is characterised by a sensitivity to light, headache and tingly, itchy rash that develops in the dermatome--an area of the skin connected to sensory fibres from the spinal column. After a period of days, the rash progresses into large, painful plaques that ooze pus, scale over and form a crust until they eventually heal over a matter of weeks. The condition can cause severe or mild scarring of the skin and may return at a later time.


A scabies rash is caused by a mite that burrows underneath the skin. It is characterised by red bumps, usually around the wrist, waistband area or in between the fingers or toes. The rash is localised, lasts up to a month and will respond to prescription medication to kill the mites.

Poison Ivy

Poison Ivy is a common rash that occurs when a person who is sensitive to poison oak, ivy or sumac comes into contact with the offending plant resins. It is characterised by red, extremely itchy blisters that occur in the areas exposed to the plants and is treated with over-the-counter or prescription topical steroid creams.

Pityriasis Rosea

This unusual-looking, itchy rash occurs on the trunk and starts with a single oval or round lesion, which spreads along the skin lines in either direction and may end up on the face, arms, neck and hands. It can last for up to eight weeks. There is no known cause for pityriasis rosea, but it is thought to be preceded by an acute infection which may produce symptoms of headache, fever and sore throat.

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