Rashes are changes in the skin's color or texture. Simple rashes are called dermatitis, which means the skin is inflamed or swollen. Some rashes are independent symptoms, but many cause itching, burning or other discomfort. There are a great many reasons for individuals to develop rashes.

Types of Rashes

Rashes occur for a variety of reasons, some relatively benign, some extremely serious. Many rashes look similar to one another so their causes may be difficult to diagnose.

Contact Dermatitis

Contact dermatitis is caused by an irritating substance. In some cases, the substance is universally irritating, like certain chemicals. In others, the irritation is the result of an allergen, such as latex, perfume, dye, or animal dander, that irritates only individuals with particular sensitivities. Plants like poison ivy and insect bites cause rashes in some individuals.

Allergic Rashes

Apart from contact dermatitis, patients may develop allergic rashes as a reaction to ingested allergens. Certain food stuffs and medications can trigger hives or other rashes in sensitive individuals.

Seborrheic Dermatitis

Seborrheic dermatitis occurs when the skin forms red, scaly, flaking patches. Though most common on the face and on the head, where it is known as dandruff or cradle cap, the condition can also be evident in the outer ear, on the eyebrows or eyelashes, forehead, sides of the nose, or chest and upper back.

Viral or Bacterial Skin Conditions

Other skin conditions, like eczema, psoriasis, impetigo, or pityriasis rosea, frequently cause rashes. Each may be diagnosed by its pattern, whether the rash is flat or pustular, and on what part of the body it occurs, although distinguishing the rashes may at times be difficult.

Systemic Diseases

Many systemic diseases have rashes as one of their symptoms. These include disorders often characterized as childhood diseases, like measles, chicken pox, rubella and scarlet fever, shingles, a disease caused by the same virus that is responsible for chicken pox, autoimmune diseases such as rheumatoid arthritis and lupus, and some sexually transmitted diseases, such as syphilis.

Rashes Caused by Sun or Heat

Heat rash is a common ailment in infants, but can occur in individuals of any age, causing small red spots or bumps which may be itchy. This rash develops when the sweat ducts in the skin are clogged, interfering with the normal process of perspiration. Too much exposure to the sun to the ultraviolet light of tanning salons may also cause a rash on affected areas. This type of rash is sometimes referred to as "sun poisoning" but the scientific name for it is polymorphous light eruption or PMLE.

Stress Rashes

Under certain circumstances, some individuals may develop rashes from stress alone, without another precipitating cause.

Treatment of Rashes

When a rash is caused by an underlying condition or disease process, the patient must be treated for the pervasive disorder. When a rash is the result of a bacterial infection, it is treated with antibiotics. When a rash stems from a virus, it may be treated with antiviral medication. Allergic rashes are normally treated with antihistamines and, when more severe, with corticosteroids. In many cases, avoidance of contact with the irritating substance or material may be sufficient to help the rash abate.

Almost all rashes that cause itching can be treated symptomatically with one or more of the following: antihistamines, soothing lotions like Calamine, topical or oral corticosteroids, baths with colloidal oatmeal, moisturizing creams or cold compresses. Wearing soft, loose clothing and taking over-the-counter pain relievers may also provide relief.

Contact Dermatitis

Contact dermatitis is a skin condition caused by an allergic reaction to certain materials that come into contact with the skin. A common cause of rashes, contact dermatitis appears on the skin after contact with the offending material or substance has taken place. It may occur immediately after contact or may take several days to appear. Typically, contact dermatitis presents as a red, itchy rash. While not serious medically, the condition may be very uncomfortable.

Triggers for Dermatitis

While an individual may develop contact dermatitis from a great variety of irritants, common culprits are:

  • Some fabrics or materials
  • Particular plants, like poison ivy
  • Soaps, detergents, cleansers, fabric softeners
  • Perfumes, hair dyes, shampoos, lotions, ointments
  • Urine in wet diapers
  • Pesticides or weed killers
  • Nickel, rubber, latex
  • Solvents or chemicals
  • Resins or glues

Diagnosis of Contact Dermatitis

Apart from inspection of the area and a medical history, the doctor may take a small skin biopsy or culture to help confirm the diagnosis. A patch test may also be administered to investigate the nature of the substance causing the irritation.

Symptoms of Contact Dermatitis

In addition to an area of itchy redness on the skin, contact dermatitis may also result in: swelling, scaling, blistering, painful sores or cracked skin. One of the significant clues to the fact that the condition is, in fact, contact dermatitis is the fact that the rash occurs only in a defined area, such as under a ring or watchband, or at the place where a particular material touches the skin. At times, when the condition is more severe, the skin may bleed or appear to have been burned by the offending substance. Symptoms may develop upon first contact or may develop only after a period of exposure.

Treatment for Contact Dermatitis

In many cases, contact dermatitis will resolve on its own, particularly if it is possible for the patient to identify and avoid the material causing the problem. Sometimes over-the-counter antipruritic (anti-itch) creams may be sufficient to cure the condition. If necessary, physicians may prescribe corticosteroids and antihistamines to alleviate ongoing symptoms. The former reduce inflammation and the latter lessen allergic reaction and diminish itching.

Complications of Contact Dermatitis

The most likely complication of contact dermatitis is a bacterial infection for which antibiotics may be prescribed. A serious lifestyle complication may occur when the contact dermatitis is caused by a material integral to the patient's work environment and a change of employment must be considered.

Poison Ivy

Poison ivy is a common plant known to cause allergic reactions in a large percentage of people. These allergic reactions usually manifest as unsightly and uncomfortable rashes on the skin. Skin rashes from poison ivy, like those from poison oak and poison sumac, are precipitated by an oily substance called urushiol found in the leaves, stems and roots of the plant. Poison ivy is found growing all over the continental United States, so rashes from poison ivy are very common.

As with other allergens, individuals may build up an intolerance to urushiol over repeated exposures, believing themselves to be immune to the substance until they develop a severe reaction. Poison ivy only develops from direct contact with urushiol and is not contagious through contact with affected individuals or blister fluid.

Causes of Poison Ivy

There are three means of making contact with urushiol and developing an allergic reaction to poison ivy:

  • Direct skin contact with the plant itself
  • Contact with materials coated with urushiol, including clothing and pet fur
  • Breathing in the smoke of the burned plants

The last method of contact on the list is the most serious since the urushiol enters the nasal passages and lungs in this manner.

Symptoms of Poison Ivy

Typically, a rash, a form of dermatitis, develops on the skin within a day or two of contact with the plant or its oil. The rash itself is not contagious to others and will not spread to other areas of the affected individual unless repeated contact is made with urushiol that remains on the body or clothing. Usually, the rash of poison ivy begins as a red, swollen, itchy area which then develops into hives and blisters. The rash may appear to spread as different areas on the body, perhaps affected at different times, react to the allergen. The itching becomes increasingly severe and may interfere with normal activities and concentration. While not usually a serious condition, the poison ivy rash can be extremely uncomfortable and distracting.

In general, the poison ivy rash will disappear within a week or two. Patients are advised not to scratch the blisters, as bacteria from the fingernails may lead to infection. It is also advisable to bathe thoroughly, wash affected clothing, and clean any affected gear or upholstery that may contain trashes of the offending oil in order to avoid reinfection.

Treatments for Poison Ivy

While the poison ivy rash normally disappears on its own, when larger areas of the body are affected, recovery may take longer. Recommended home treatments for the itchy rash may include:

  • Taking baths in colloidal oatmeal
  • Applying hydrocortisone cream to the affected areas
  • Taking over-the-counter antihistamines
  • Taking over-the-counter pain relievers

Complications of Poison Ivy

While most cases of poison ivy are not serious, medical attention should be sought for any of the following symptoms:

  • High fever or other symptoms of infection
  • Widespread rash that does not improve in days
  • Rash in extremely sensitive areas, such as the eyes or genitals

A physician should be consulted for any symptoms of infection since an antibiotic will need to be prescribed. If the rash is severe or resistant, the doctor may prescribe oral corticosteroids. If the smoke of these plants has been inhaled, or the eyes or genitals have been affected, one or more specialists may have to be consulted.

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