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Rashes are caused by many things, from allergies to infections. Many people get anxious when they notice a new patch on their skin of some unknown cause. Rashes can be scaly, itchy, bumpy, or blister, but the unique characteristics of the rash can reveal the cause and effective treatments.

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Eczema

One of the most common skin rashes is eczema or atopic dermatitis. This chronic skin disorder appears as dry, scaly, itchy patches. The skin may be red or swollen or develop small bumps that open when scratched. The cause is unknown, though it runs in families and can be triggered by irritants like detergents, irritating fabrics, stress, and extreme hot or cold temperatures.

eczema on backs of hands
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Allergic Contact Dermatitis

Allergic contact dermatitis is a reaction that starts with exposure to an allergen followed by an allergic reaction after exposure. The most prominent symptom of allergic contact dermatitis is itchiness. The rash is often red and raised but can also be scaly or swell up. Where the rash appears and its pattern depends on the allergen and the exposure. Contact dermatitis often spreads with scratching and can develop as long as two or three days after exposure to the irritant.

itchy allergic contact dermatitis rash on forearm
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Ringworm

Ringworm is a common skin rash caused by a fungus. The name is something of a misnomer, as this rash is not caused by a worm, but it does have a ring-like shape. The rash is typically red, dry, and itchy. The fungus that causes ringworm can live on pretty much any surface, including clothing, towels, and bedding, making it particularly contagious.

ringworm infection on the forearm
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Rosacea

Rosacea is a common skin rash that normally affects only the face and the skin around the eyes, though it may spread to the chest or neck. It appears as red pimple-like bumps and broken blood vessels, and it typically begins in middle age. Although more than 14 million people in the U.S. have rosacea, its cause is unknown.

rosacea on a woman's cheeks
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Shingles

Singles is caused by the same virus that causes chickenpox. The shingles rash typically appears as a stripe on one side of the body, following a nerve. Some people have symptoms like tingling or itching before the rash even appears. The rash consists of red blisters that usually last a week before scabbing over. They can take as long as four weeks to clear up completely.

digital illustration of a shingles outbreak on the back
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Measles

The measles rash is caused by a virus. A week or two after exposure, symptoms like high fever, nasal congestion, and a runny nose begin. The rash usually appears a few days after these initial symptoms. Small raised bumps start on the face and spread downward, sometimes reaching the feet. The bumps may join and appear more as large red patches than individual spots.

little boy with measles getting medical checkup
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Hand, Foot, and Mouth Disease

Hand-foot-and-mouth disease is a viral infection and one of the most common skin rashes in children. Early symptoms include sore throat, fever, and generally feeling unwell. A day or two after these symptoms begin, a rash of blister-like sores develops on the palms and soles and in the mouth and throat. These bumps are not itchy, but they are very painful and cause children a lot of distress.

child's hands with hand, foot, and mouth disease rash
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Psoriasis

Psoriasis is a common, chronic skin condition with no cure. It appears in cycles and can flare for weeks or months at a time before going away for some time or even going into remission. Rashes appear as itchy red, scaly patches commonly on the knees, elbows, scalp, or trunk. Some forms of psoriasis develop thick, silvery scales, while others can crack or bleed.

cropped image of psoriasis on model's elbow
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Tick Bite

Lyme disease can develop from tick bites, and identifying the rash helps ensure early treatment. The rash caused by Lyme disease appears in stages. The first stage will often have a bite mark in the center of a red ring, commonly referred to as a bullseye rash. At this stage, the area will be smooth but warm and may itch or hurt. A crust may appear at the edges.

Stage two begins as the disease develops, and circular rashes may appear on other parts of the body away from the bite, indicating the infection is spreading.

Stage three is advanced Lyme disease. The skin may shrink or become tight. Hair falls out, and deep lines can form across the surface of the skin. At this stage, some people develop tumors, and the disease affects the heart and nervous system. Advanced Lyme disease is dangerous, which is why identifying the early rash is essential.

tick about to bite skin
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Hives

Hives or urticaria result from a skin reaction or allergy and are usually raised, red, and itchy. They can appear anywhere on the body and often change shape, disappearing and reappearing while the reaction runs its course. Some people have chronic hives that last for longer than six weeks, triggered by stress, heat, and exercise.

woman scratching at hives allergic reaction on her arm

Disclaimer

This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.