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
- Allergic Rashes
- Seborrheic Dermatitis
- Viral or Bacterial Skin Conditions
- Systemic Diseases
- Rashes Caused by Sun or Heat
There are three major groups of skin diseases caused by allergy: eczema, allergic contact dermatitis and hives. Eczema occurs most commonly in children and involves red, thickened, swollen patches of skin on the cheeks, scalp, neck and trunk that itch and can be painful. Allergic contact dermatitis describes the onset of a rash, swelling, blistering or other effect after the skin touches an irritating substance such as clothing materials and dyes, latex, cosmetics, soaps, perfumes or certain plants like poison ivy. Sometimes the reaction is triggered by exposure to ultraviolet light (called photoallergy), for example putting on sunscreen and stepping outside. Hives, also called urticaria, are itchy rashes with bumps resembling insect bites. They can occur in small patches or all over the body, and last anywhere from a few minutes to several months.
Eczema is a common skin disorder that manifests itself as itchy skin and a red rash; it is particularly common in infants and young children. Eczema most often develops as a result of an allergic reaction, or an immune-system malfunction. It can cause irritation and inflammation anywhere on the body, but is especially prevalent on the face, the insides of the arms, and behind the knees. In infants with eczema, the scalp is frequently affected.
Atopic dermatitis is the most common, chronic, and severe form of eczema. It occurs most often in those with other allergic conditions, such as asthma or hay fever, and who have family members with the same issues. Eczema is not contagious even with direct skin-to-skin contact.
Causes of Eczema
While the precise cause of eczema is unknown, certain substances or circumstances can trigger symptoms in susceptible individuals. Patients with eczema may have adverse skin reactions to many common household products, such as soaps, perfumes, lotions or detergents, as well as to animal dander. They may also develop eczema outbreaks as a result of upper respiratory infections. In some cases, eczema may occur from a food allergy.
Although eczema is quite common in infants, most outgrow it by the age of 2. For infants prone to outbreaks, it is best to avoid using products or fabrics that may irritate their skin, and to avoid feeding them foods that seem to precipitate reactions. For adults, too, the best treatment for eczema may be prevention. By avoiding triggers such as coarse fabrics, extreme hot or cold, animal dander and certain soaps or detergents, patients may be able to keep outbreaks at bay. Although stress is often a factor that worsens the condition, eczema itself, with its discomfort and displeasing appearance, can also be a cause of stress.
Symptoms of Eczema
Eczema usually appears as a red rash on the skin, and can include the following symptoms:
- Raised crusty patches
- Blisters that ooze
- Dry or scaly skin
Skin discoloration can also be a symptom of eczema.
Diagnosis of Eczema
Eczema is diagnosed by physical examination and patient consultation. It is important that, in addition to a full patient history, the attending doctor take a full family history. Because many people with eczema often have other allergies, allergy tests may be prescribed or performed so that possible triggers can be targeted.
Treatment of Eczema
There are several treatments available to ease the discomforts of eczema. Cold compresses and over-the-counter preparations to address itching may be recommended. If symptoms persist or become more severe, stronger medications may be prescribed. It is important to treat eczema symptoms because the condition breaches the integrity of the skin, allowing bacteria to invade and cause infection. Itching has to be addressed because scratching can lead to crusting and scabbing of the skin, further breaking down tissues, and increasing the risk of infection. Treatment of eczema may include the following:
- Topical corticosteroids
- Changes in bathing and laundering habits
- Antibiotics (if infection is present)
- Immunomodulators (such as cyclosporine)
Because both phototherapy and immunomodulators have been linked to an elevated risk of cancer, they are usually prescribed only during severe flareups, and for children older than 2 years of age.
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. A poison ivy rash only develops from direct contact with urushiol and is not contagious through contact with affected individuals or blister fluid.
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.