Rash Alternative Names
A rash is when an area of the skin breaks out and changes in appearance. It may affect one small spot of skin or the entire body.
What is going on in the body?
There are many skin changes that can occur with a rash, including:
Skin can react or break out for many different reasons, ranging from allergic reactions to infections and even cancer.
- colour changes
What are the signs and symptoms of the condition?
There are many questions a doctor may have when someone complains of a rash. For instance, he or she may ask:
The doctor may ask about other symptoms, which can help narrow the list of possible causes. For instance, a person may be asked about his or her sexual history or whether he or she has had arthritis or weight loss.
- how long the rash has been present
- how the rash started and changed over time
- whether or not the rash itches
- whether or not the person has a fever or chills
- whether anyone the person knows has had a similar rash
- whether the person has any allergies
- what medications the person is taking
- whether the person has had similar or other rashes in the past
- whether the person has been bitten by something
What are the causes and risks of the condition?
There are many possible causes of a rash. General categories include:
Other causes are also possible. Sometimes the cause is not found.
- infections, such as ringworm; syphilis; measles; chickenpox; scabies; roseola; impetigo; genital herpes and herpes zoster; Kawasaki disease; hand, foot, and mouth disease; cat scratch disease; Group A strep infections; staphylococcus infections; and scarlet fever
- allergic reactions, which can be from medications, metals, chemicals, soaps, lotions, foods, or other materials
- primary skin diseases, such as acne, psoriasis, eczema, or rosacea, which often occur for unknown reasons
- autoimmune diseases, such as systemic lupus erythematosus, scleroderma, and inflammatory bowel disease
- other systemic conditions, such as diabetes, nephritis, or pregnancy
- skin cancer or a cancer deeper in the body that causes a rash
- inflammation of blood vessels, called vasculitis, in the skin
- poor circulation, which commonly causes rashes in the lower legs
- reaction to various childhood vaccinations, such as the chickenpox vaccine
- heat or sun exposure
What can be done to prevent the condition?
Prevention depends on the cause, which is often difficult to diagnose. Those with allergies should avoid the substances they are allergic to whenever possible. Routine childhood vaccines can prevent some infections that cause a skin rash, such as measles and chickenpox. Avoiding the sun and using sunscreen can reduce the risk of skin cancer.
How is the condition diagnosed?
The cause of some rashes can be diagnosed after a history and examination of the rash. Other rashes may be more difficult to identify. Further tests may be needed, including blood or urine tests. Sometimes, a biopsy of the affected skin is needed. This is when a small piece of skin is removed with a special instrument. The skin can then be analysed in the laboratory to help try to figure out the cause. Further tests may be needed in some settings, depending on the suspected cause. For instance, the doctor may order a chest x-ray if he or she suspects that a lung infection is causing the rash.
What are the long-term effects of the condition?
Some rashes, such as severe acne, may cause permanent scarring of the skin. Other rashes may become infected because of skin breakdown. In very rare cases, such as in cases of severe allergic skin reactions, rashes can even result in death.
For most rashes, the long-term effects are related to the underlying cause. For instance, cancer or serious infections that cause rashes may result in death. Rashes associated with pregnancy often go away after delivery and have no long-term effects.
What are the risks to others?
In some cases, a rash can be contagious and spread to others. In most cases, however, a rash poses no risk to others.
What are the treatments for the condition?
Affected skin should be kept clean, especially if there is skin breakdown. Specific treatment depends on the cause. For instance, those with infections may need antibiotic pills or creams applied to the rash. Those with allergic reactions may need antihistamines or corticosteroid pills or creams. Those with autoimmune disorders may need drugs to suppress the immune system. Those with cancer or poor circulation may need surgery.
What are the side effects of the treatments?
Side effects depend on the treatments used. All medications have possible side effects. These may include allergic reactions, stomach upset, and headaches. Specific side effects depend on the drugs used. For instance, antihistamines often make people sleepy. Surgery carries a risk of bleeding and infection. Specific side effects depend on the type of surgery.
What happens after treatment for the condition?
This depends on the cause of the rash. If the rash goes away, people may or may not need further treatment. For instance, those with diabetes or poor circulation need further treatment and monitoring even after their rashes go away. Those who have ringworm, a fungal infection of the skin, are cured after treatment. They can return to normal activities without further treatment.
How is the condition monitored?
People generally can monitor their own rashes at home. Those with skin breakdown need to watch for infection until the skin heals over. The doctor may also want to monitor the rash periodically, depending on the cause. Further monitoring depends on the cause of the rash.
Author: Adam Brochert, MD
Reviewer: HealthAnswers Australia Medical Review Panel
Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia
Last Updated: 1/10/2001
Potential conflict of interest information for reviewers available on request