Rashes

What is a rash?

Rash is a broad term used to describe specific changes to the skin. Such changes include redness, swelling, inflammation, scaling, or changes in color. Rashes can have symptoms such as itching, pain, and discomfort. They can greatly affect quality of life or ability to sleep. Some rashes can cover large parts of the body and yet have no symptoms other than their appearance. Rashes are often referred to as a "dermatitis". This is simply a medical term meaning "skin inflammation" so it is not a diagnosis in and of itself. 

What causes rashes?

As there are hundreds of different types of rashes, there are also numerous causes of rashes. For many types of rashes, we know an exact cause. These would include rashes caused by bacteria, fungus, viruses, medications, specific environmental exposures, or autoimmune diseases. An example would be shingles which we know is due to the same virus that causes chickenpox. For many rashes, we do not know a specific cause as they are due to a mixture of genetic and environmental factors that are not fully understood. These would include rashes such a psoriasis which usually runs in families but does not have a specific trigger common to all patients. 

How is a rash diagnosed?

This is not an easy question. As there are hundreds of different types of rashes and many look the same, there is no easy way to quickly and easily identify all rashes. The best way to diagnose a rash is to see a dermatologist who is specifically trained to diagnose skin diseases. Dermatologists spend thousands of hours studying textbooks and photos and then put this knowledge into practice seeing thousands of patients and rashes each year. Even with all this training, not all rashes can be immediately identified. Some require additional tests such as a skin biopsy where a sample of skin is taken and examined under the microscope. Other tests include cultures for bacteria, fungus, or viruses.

 

Many, but not all rashes, can be identified by a visual inspection often confirmed by specific information obtained from a medical history. There are many rashes that dermatologists can diagnose in less than a second of examination. Some patients are impressed by this, while others may be frustrated that a dermatologist could so easily diagnose something that other physicians may have missed. While this does happen some of the time, unfortunately there are still many times when an exact diagnosis cannot be made even with additional testing. Even the best dermatologists in the world are not able to give an exact diagnosis every time. 

How are rashes treated?

Treatment will be determined by the specific diagnosis or suspected cause of the rash. For many rashes, a topical anti-inflammatory such as a topical steroid is all that is needed to calm down the skin and allow it to heal. Other times an anti-fungal or anti-bacterial medication may be needed. For more severe infections, oral or systemic medications may be needed. This may include pills or even injections such as the ones you have probably see on TV commercials used to treat psoriasis or eczema. Some medications will only need to be used for days, while others may be needed for many years. Fortunately not all rashes require treatment as many will resolve on their own.