Causes of Rash

There are many causes of rash. So many that it’s hard to list them all!

Simple Causes: There are many simple causes of a rash or rash-like skin conditions.

Skin Complaints: Some common skin conditions include:

Contagious Infection Causes: There are many different infections that can lead to a rash.

Rash Causes: Some of the other causes of rash include:

Non-Infectious Systemic Conditions: Various systemic conditions may cause rash:

Pustular Rash: Some of the causes of a Pustular Rash include:

Bullous Rash (Blistering Rash): Various causes of a bullous rash with blisters or bullae include:

Skin Ulcers: There are various causes of skin ulcers or an ulcerative skin rash:

Butterfly Rash: Causes of a “Butterfly Rash” across nose and cheeks:

Larger Circular Rash: Disorders that cause a distinctly circular-shaped rash or circular redness areas that are larger than small circular lesions (e.g. pustules, pimples, red spots, etc.), may include:

Bullseye Rash (Target Rash): Causes of a bullseye rash (a target-shaped rash) with a central redness area and concentric red circular rings include:

Radiating Rash: A rash with a central point and radiating lines of redness may be indicative of:

One-Sided Rash: A local rash is obviously small and on a single side of the body. The occurrence of a non-local rash that is nevertheless on one-side of the body may be caused by:

Hemorrhagic Rash: Some of the infectious causes of a Hemorrhagic Rash:

Purpura Causes: Non-Infectious causes of purpura (petechiae, ecchymoses, hematoma, hemorrhagic rash):

Purple Striae: Causes of Purple Streak-like Marks (Purple Striae):

Causes of Skin Redness: A red skin rash, without any obvious skin changes to its texture, could be caused by:

Read more about: skin redness.

Other Infections. A localized infection can cause a skin rash or a rash-like appearance. Less commonly, a systemic infection can cause rash, and is often very serious in this case.

Chronic Rash Conditions: various chronic skin diseases can result in regular rashes, or reoccurring rashes:

Serious Disease Causes: What if it’s not just a skin condition, but a symptom of something more serious. Some of the major chronic diseases where a rash is one of the early symptoms include:

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Back to: « Rash

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Find out about some causes of rashes on the pages below.

Source: New Zealand Health1

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If the rash is over all or most of your body, look for it here:


Source: New Zealand Health2

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Other illnesses similar to scarlet fever

There are many other illnesses that can cause a spotty or blotchy red rash, including:

See your GP or call NHS 111 for advice if you or your child has a rash and you're worried.

Call 999 for an ambulance or go to your nearest accident and emergency (A&E) department if you think you or your child might have meningitis.

Source: NHS Choices UK3

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You’ve probably had a rash at some point or another, whether from poison ivy or the chickenpox or something more unusual. Why does your skin break out in red blotches like that? More important, is there anything you can do about it?

Eczema, or atopic dermatitis, is a dry, red, itchy rash that affects up to 1 in 5 infants and young children. It often improves over time, although it can last into adulthood or start later in life. In this condition, the water-tight barrier between skin cells gets weak, which lets moisture out and other things in. That’s why people with atopic dermatitis have to moisturize their skin, and they’re more susceptible to skin infections.

“The skin is the outermost sentinel for fighting off bacteria and noxious agents,” says Katz. “If the barrier is broken somehow, you can become more allergic to things.”

A skin allergy, or allergic contact dermatitis, produces a red, itchy rash that sometimes comes with small blisters or bumps. The rash arises when the skin comes in contact with an allergen, a usually harmless substance that the immune system attacks. Allergens trigger allergic reactions. Allergens can come from certain soaps, creams and even pets.

Your immune system might not react the first time you encounter an allergen. But over time, your immune system can become sensitive to the substance. As a result, your next contact may lead to inflammation and an allergic rash.

“The most common form of dermatitis that is seen anywhere is an allergic contact dermatitis to nickel,” says Katz. “Why? Because of ear piercing.” Many inexpensive earrings are made of nickel, and over time, wearing nickel earrings can cause an allergic reaction to the metal.

Other common causes of allergic dermatitis are poison oak and poison ivy. The stems and leaves of these plants produce a chemical that’s likely to cause allergies. If you touch one of them, wash your skin as soon as possible. The chemical can also remain in clothing for a long time, so it’s important to wash any clothes or shoes—or even pets—that come into contact with these plants.

Mild cases of allergic contact dermatitis usually disappear after a few days or weeks. But if the rash persists, is extremely uncomfortable or occurs on the face, it’s important to see a physician. A doctor can prescribe medications that will tone down the immune reaction in the skin. This eases swelling and itching and will protect your eyes and face.

The immune cells of the skin can also produce rashes when they react to invading germs—like bacteria, fungi and viruses. Bacterial and viral infections within your body can cause your skin to break out in spots as well. The chickenpox virus, for example, can cause itchy spots in children. Years later, in older adults, the same virus may reappear as shingles, bringing a painful rash and high fever. Vaccines can prevent several rash-causing diseases, including chickenpox, shingles and measles.

Certain drugs, including antibiotics like amoxicillin, may also cause itchy skin rashes. If you’re allergic to a drug, a rash can be the first sign of a serious reaction. As with other allergies, a reaction to a drug may not occur the first time you take it. It could show up after several uses. Not all drug rashes are due to an allergy, however. If you break out in itchy spots after starting a new drug prescription, contact your doctor right away.

While most rashes get better with time, some can last a lifetime. Psoriasis, a condition where skin cells build up into thick red patches, tends to run in families. “It’s a complex genetic disease, in that there’s not one gene that causes psoriasis but many,” says Katz. Even though none of these genes alone has a great effect on the disease, knowing which genes are involved can help researchers design potential new treatments. Other long-term diseases that can produce rashes include autoimmune diseases, such as lupus, and some forms of cancer.

Source: NIH News in Health (NIH)4

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Zika virus: Zika infection may cause a rash that could be confused with other serious diseases such as measles or dengue, so it's important to check with a health care professional to rule out these diseases.

Source: New Zealand Health5

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Chilblains: Chilblains are small, itchy swellings on the skin that occur as a reaction to cold temperatures.

Source: NHS Choices UK6

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Stevens-Johnson syndrome: The syndrome often begins with flu-like symptoms, followed by a red or purple rash that spreads and forms blisters. The affected skin eventually dies and peels off.

Source: NHS Choices UK7

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Stretch marks: Before stretch marks appear, the affected skin will become thin, flattened and pink, and may feel itchy.

Source: NHS Choices UK8

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Some causes may include:9 Causes of Skin Rash:

Causes List for Rash

List of possible causes of Rash or similar symptoms may include:10

... Full Causes List for Rash »

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  1. Source: New Zealand Health: your-health/ conditions-and-treatments/ diseases-and-illnesses/ rashes
  2. ibid.
  3. Source: NHS Choices UK: conditions/ Scarlet-fever/ 
  4. Source: NIH News in Health (NIH): issue/ apr2012/ feature1
  5. Source: New Zealand Health: your-health/ conditions-and-treatments/ diseases-and-illnesses/ zika-virus
  6. Source: NHS Choices UK: conditions/ chilblains/ 
  7. Source: NHS Choices UK: conditions/ stevens-johnson-syndrome/ \
  8. Source: NHS Choices UK: conditions/ Stretch-marks/ 
  9. Source: Human Phenotype Ontology
  10. Source: Algorithmically Generated List

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Note: This site is for informational purposes only and is not medical advice. See your doctor or other qualified medical professional for all your medical needs.