A rash may be an outward sign of condition affecting the body as a whole. Infectious fevers, emotional disorders, and allergies may all have accompanying rashes.
However, rashes are equally likely to be an indication of a localized disorder in the skin, the kind of inflammation that is commonly called dermatitis, included in this type of local inflammation re diaper rash, prickly heat, eczema, and fungal infections.
Types of rashes
Rashes take many different forms. A rash that is present at the start of an illness is called a primary rash. The rash may subsequently change in character and appearance during the course of the causative disease, owing to complications or in response to the treatment used. New rashes or changes in the original rash are called secondary eruptions, and each has its own set of characteristics.
- Primary rashes
- Secondary rashes
The most common of the primary rashes shows as areas of redness known as macules. Any abnormal change in the color of the skin over a limited area qualifies as a macular rash; the redness itself is known as erythema.
Sometimes, in the early stages of measles, the rash consists of hundreds of tiny red spots, each spot discrete or separate from the others.
In other cases the spots enlarge until they run into each other to form blotchy patches. This is called a confluent rash. Usually, if a thumb is pressed on a part of the rash the area will not fade, but a white area may remain temporarily. This is an important diagnostic feature and is characteristic of many conditions; it is especially noticeable in typhoid fever.
The second common type of rash consists of spots which are not necessarily red but project above the surface of the skin. They can be felt as small raised pimples if a fingertip is run over the skin, in contrast to a macular rash which is not raised. The pimples are known as papules, and the rash is called a popular rash. A maculopapular rash has both macules and papules.
When the rash is made up of pimples containing a clear or milky fluid doctors refer to it as vesicular and each pimple is vesicle. Chicken pox and herpes simplex are typical vesicular rashes.
A rash may also consist of raised areas of skin much larger than papules. These are known as welts, and they are usually white at the center and pink or red at the outer edge. This type of skin eruption, called Urticaria or hives, is usually highly irritant and indicates an allergic reaction that releases histamine into the skin, causing inflammation.
In some cases a primary rash, whatever its type, simply fades away or resolves as the condition improves, without going through any secondary stage and without leaving scars or any other aftereffects. Secondary eruptions are quite common, however, and may manifest themselves in a variety of ways.
Often the area of skin covered by the rash peels away. This normally occurs if the original rash was a dry macular or papular one or, as in some cases, a mixture of the two.
The type of rash usually seen in the later stages of chicken pox, by contrast, is Pustular: that is, the spots have become infected pustules, containing pus. This type of moist lesion will dry out to form a crust or small scab. New skin will grow under the scabs, which will eventually separate and drop off. If the deeper layers of skin have been affected, as when chicken pox spots are scratched, there may be scarring in the form of pockmarks, or tiny pits in the skin.
Other types of secondary rash include a thickening of the area of the skin concerned, giving it a leathery look and texture that is characteristic of long term inflammation or chronic inflammation. Similarly, permanent discoloration or pigmentation of the skin may develop in the area of the rash.
Finally, entire areas of skin may break down, exposing the underlying or subcutaneous tissue. Without this protective covering of skin, ulcers can form which are very likely to become infected by bacteria from the atmosphere, especially in moist, heavily contaminated environments. This sometimes happens with diaper rash, cold sores, or rashes from shingles.
- Skin rashes can be caused by allergies, excessive heat, contact with certain plants, infections, or bug bites.
- Some plants cause rashes when they are touched. The most common of these are poison ivy and poison oak. Both are shiny green and tune orange and red in the fall. Each stem has three leaves at the end of it.
- Allergies may appear as a red, itchy rash or even like small mosquito bites. Allergies can also cause hives, a blotchy rash.
- Fungus may appear in the form of ringworm or athlete’s food, or red, itchy crusty patches of skin. Impetigo, a bacterial infection, forms honey colored sores on the skin.
What to do
If you’re sure it’s an allergy, you may want to take an over-the counter antihistamine, available at the drugstore. Ask the pharmacist to recommended one. You can also try anti-itch cream and powders. If you experiences swelling in the face or tongue or have difficulty breathing, seek medical attention immediately.
- Rash from plants
Wash the skin completely to remove the plant oil. If itchiness remains, oatmeal or Aveeno baths can help. A hot bath or shower followed by calamine lotion is also beneficial. All of these items can be found in the drugstore.
Soak off the crust with warm water, wash with soap and water, and apply antibacterial cream.
- Athlete’s foot and ringworm
For athlete’s foot, wash feet well twice a day; dry them thoroughly and apply antifungal medicine. It’s important to put on clean socks each time feet are washed. Wearing sandals or canvas sneakers lets moisture escape and helps and feet heal. If very uncomfortable, cream or liquid treatments may be applied. These rashes and infections are common and nothing to be embarrassed about. If ringworm appears on your scalp, you need to see your doctor for medication.
Common skin rashes
In order to know how to treat a rash, it is best to know the cause. The following table lists some of the conditions that most commonly cause rashes, together with a description of characteristic features. It is not means to be a list of all possible causes of skin rash, however, consult your health care provider for a definitive diagnosis of your rash.