Medically Reviewed By William C. Lloyd III, MD, FACS

What is a rash?

A rash is an inflammatory reaction of the skin. Rashes can be caused by a wide variety of mild to serious diseases, disorders and conditions. Rashes can affect a small area of the skin or the full body and occur in all age groups and populations.

Rashes vary greatly in appearance, extent and severity, depending on the underlying cause. Rashes can be red, white, purple or silver in color, and raised, bumpy or flat in texture. They can appear as dots or spots or occur in a large, continuous area. Rashes can also include scaling or flaking off of skin cells.

Because of the range of possible causes of a rash, a correct diagnosis of the underlying disease, disorder or condition  is very important. Contact your health care provider for a physical exam.

A rash of purple spots can indicate a serious, potentially life-threatening condition, such as meningitis or allergic purpura. A rash that is associated with allergies combined with shortness of breath, wheezing, or swelling of the face, mouth or throat is also a symptom of a serious, potentially life-threatening allergic reaction called anaphylaxis. Seek immediate medical care (call 911) if you, or someone you are with, have any of these symptoms.

What other symptoms might occur with a rash?

A rash may be accompanied by other symptoms, depending on the underlying disease, disorder or condition. Other symptoms may affect the digestive tract, respiratory system, nervous system, reproductive system, cardiovascular system, immune system, or integumentary system (skin and associated tissues).

Skin symptoms that may occur along with a rash

A rash may occur with other symptoms affecting the skin including:

  • Blistering

  • Burning

  • Inflammation

  • Irritation

  • Itching

  • Redness

  • Scaling

  • Swelling

Other symptoms that may occur along with a rash

A rash may occur with other symptoms related to other body systems including:

Serious symptoms that might indicate a life-threatening condition

In some cases, a rash may occur with other symptoms that might indicate a serious or life-threatening condition, such as anaphylaxis, that should be immediately evaluated in an emergency setting. Symptoms that may indicate a serious or life-threatening condition include:

What causes rashes?

Rashes can be caused by a wide variety of diseases and conditions, such as infection, inflammation, allergic reaction, parasite and insect bites, and autoimmune processes.

Infectious causes of rashes

A rash may be caused by an infection including:

Allergic causes of rashes

A rash may be caused by an allergic reaction including:

Autoimmune causes of rashes

A rash may be caused by an autoimmune response including:

Parasites, insects and arachnids that cause rashes

A rash may be caused by parasites, insects or arachnids including:

Other causes of rashes

A rash may also be caused by problems in body systems other than the skin including:

Life-threatening causes of rashes

In some cases, a rash may accompany a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:

  • Allergic purpura

  • Anaphylaxis

  • Meningitis

  • Severe allergic reaction

When should you see a doctor for a rash?

Often, rashes are not serious and the problem resolves on its own with home treatment. However, it can be hard to tell the difference between rashes since they can look very similar. So, there are times when seeing a doctor is the safest option to determine the underlying cause.

Contact your doctor right away or see a doctor immediately when a rash:

  • Covers your whole body

  • Is blistering or appears infected with swelling, warmth, crusting, or red streaks

  • Is painful or occurs with swollen lymph nodes, joint pain, or a sore throat

  • May be the result of a tick bite

  • Starts suddenly or is spreading quickly or worsening

Call 911 or go to your nearest emergency room for a rash when:

How do doctors diagnose the cause of a rash?

To diagnose the underlying cause of a rash, your doctor will take a medical history, perform an exam, and possibly order testing.

Questions for diagnosing the cause of a rash

Questions related to your symptoms that your doctor may ask include:

  • Describe the rash. Where is it? What does it look like?
  • Did the rash develop suddenly or slowly? Is it constant or does it come and go?
  • Does the rash occur with any particular activity, such as eating? 
  • What other symptoms are you having?
  • What, if anything, makes your symptoms better or worse?
  • Are you using any new soaps, detergents, or personal products? If so, when did you start?
  • Have you been in recent contact with any unusual or new substances or environments, such as poison ivy or new medications or food?
  • Have you experienced any recent insect or animal bites?
  • Provide your full medical history, including all medical conditions, surgeries and treatments, family history, and a complete list of the medications and dietary supplements that you take.

Exams and testing for diagnosing the cause of a rash

During the physical exam, your doctor will look at your skin from head to toe, if necessary, and possibly mark it. The exam will also check your heart, lungs, abdomen, and ears, nose and throat. Your doctor may do a neurological evaluation as well.

Most of the time, your doctor can pinpoint the problem by examining the rash and listening to your answers. Sometimes, testing may be necessary including:

  • Allergy testing, which usually involves skin testing but may require blood tests as well
  • Blood tests, including a complete blood count
  • Skin scrapings or skin biopsy to examine the skin microscopically

It is not always possible to diagnose an underlying cause or condition. If the problem persists and your provider is unable to determine a cause, seeking a second opinion may give you more information and answers.

How do you treat a rash?

Treating a rash depends on the severity of the rash and the underlying cause. The goal is to correct the underlying problem and improve your comfort. When medications are the cause, switching to another drug is an option.

To help resolve the rash and stop any itching, doctors may recommend medications including:

  • Antibiotics or antifungals, which may be necessary if a bacterial or fungal infection is causing the rash
  • Antihistamines, which block histamine—a substance that plays a role in allergy and itch. Diphenhydramine (Benadryl) is a common example.
  • Corticosteroids, which include both topical and oral medicines. There are both over-the-counter and prescription-strength topical products. Creams have fewer side effects than taking an oral steroid, but sometimes an oral steroid is necessary. Hydrocortisone and prednisone are examples of corticosteroids.
  • Other topical medicines, which includes over-the-counter products, such as cooling gels, anti-itch lotions, and skin anesthetics

Home remedies for a rash

In addition to over-the-counter treatments, there are several remedies for managing a rash at home. This includes:

  • Applying a daily moisturizer for sensitive skin after your bath or shower
  • Avoiding irritants, allergens, and harsh soaps, cleansers and detergents
  • Bathing or showering with cool or warm water instead of hot water, which can dry and irritate the skin, and using oatmeal-based bath products
  • Dressing in loose, lightweight clothing during hot weather
  • Humidifying the air in your home
  • Placing cool compresses on the itchy skin and applying calamine lotion
  • Wearing sunscreen and a bug repellant when outdoors

Alternative treatments for a rash

There are various alternative treatments that may be helpful for skin conditions, including acne, dermatitis, rashes and itching. Some have more evidence for effectiveness than others. Two common ones are aloe vera and acupuncture.

Many over-the-counter skin care products contain aloe vera. It has various uses on the skin and has promising results for psoriasis, burns, skin damage from radiation, and skin pigmentation changes. The gel form may help relieve itching and redness from rashes.

Acupuncture also shows promising results for managing skin conditions, especially itching from rashes and atopic dermatitis. In reducing the sensation of itch, acupressure also seems to show promise. Acupressure uses the fingertips or small pellets to apply pressure instead of using needles that penetrate the skin. One study found it improved itch and overall skin condition for people with eczema.

What are the potential complications of a rash?

In some cases, a rash can lead to complications, especially if the itching is severe and leads to breakdown of the skin. Complications include:

  • Bacterial or fungal infection of the skin

  • Cellulitis (an infection of the skin and surrounding tissues caused by a growing bacterial or fungal infection)

  • Open sores and lesions

  • Permanent change in skin texture or scarring

  • Permanent skin discoloration
Was this helpful?
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jul 1
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