Rashes cause not only physical symptoms but also psychological distress. Physical discomfort is common, as is the worry associated with the rashes. “What did I come in contact with?” “What did I ingest?” “When will the rash go away?”
There are many causes of rashes, but definitive diagnosis can be elusive. Rashes can be caused by viruses such as chicken pox and measles. It can be transmitted through fungus such as ringworm. (And new research shows that fungi is the cause of dandruff and Seborrheic dermatitis.) Rashes are a common sign of adverse reactions to medications. Allergic reactions cause hives. Mites cause scabies and bedbugs leave large bites on limbs. Other rashes have no known causes.
Based on this list of causative factors, it is clear that rashes are not simply due to poor hygiene, though hygiene is an important factor in keeping the skin healthy and vibrant.
Some rashes have textbook-like characteristic appearances, like the distinctive pattern of bed bug bites: the three large bites in a row are referred to as “breakfast, lunch and dinner.” Lyme disease has the bullseye rash. Pityriasis (a non-dangerous, self-limiting viral rash) has the evergreen tree-shape appearance. But it is common for rashes to not cooperate with these textbook appearances. The key then, is to know the defining characteristics and underlying pathophysiology. For example, ringworm makes a distinctive round ring appearance. But most of the time there is no ring. There is a saying in dermatology that an uncommon appearance of a common condition is more common than a common appearance of an uncommon condition.
Sometimes the general signs and symptoms help point to the diagnosis. Hives have general allergy symptoms together with the rash. Hives help alert you to further potentially dangerous effects of the allergy. Hives and allergic reactions can progress to anaphylaxis. Think of it like this: the same allergic reaction that is manifesting on the skin is also transpiring inside the body, such as in the lungs. Just as the skin is irritated and swelling, so is the lungs. And when that happens, it can make breathing difficult, if not impossible. Similarly, viral rashes have systemic signs and symptoms such as fever and upper respiratory symptoms.
The patient history is crucial in helping make the correct diagnosis. For example in contact dermatitis, such as from poison ivy or other irritants, there will be streak marks on the skin in the parts that have brushed along the poison ivy plant. Likewise if the person scratched the poison ivy rash and then touched another part of themselves, it would also leave visible lines in the shape of the scratch.
If the rash was due to a new detergent, the rash would be on the part of the skin which came in contact with the clothing. For example, if there were short sleeve shirts, there would be no rash on the lower arms. These appearances are one way rashes are identified and diagnosed.
Drug rashes that occur as a negative reaction of medication happen when the person is taking the offending medication. It does not appear days later.
Acute rashes are diagnosed and treated by a primary care provider or urgent care clinic. Even acute exacerbations of chronic conditions are frequently treated in primary care. Chronic skin conditions are usually treated by dermatologists. It can be difficult to get an appointment with a dermatologist, but many urgent care clinics have relationships with dermatologists and can help with expedited follow-up appointments – much like emergency departments.
Many rashes are self-limiting, meaning they resolve with or without treatment. Treatment often consists of providing comfort measures, such as stopping the itching or reducing the appearance of the lesions. For these, the main treatments are oral antihistamines such as Benadryl and topical steroids. If the rash is a symptom of a deeper issue, it is that issue that is addressed – no matter how well the lesions for bed bugs are treated. Unless the bed bugs are taken care of, there will be no cure. Rashes that are caused by fungal infections are treated with topical antifungal creams and even oral anti fungal medications. Sometimes just knowing what the rash is and the cause, can produce relief.
Written by: Jacob Gerlitz