What is a skin rash?
A rash is clinically defined as a temporary eruption on the skin affecting the colour, appearance, and texture of the skin. Generally a red in colour, a skin rash may be localized to one part of the body or may occur throughout the body. One of the ways your body tells you that you are allergic to a substance is through a rash
There are many types of rashes, that are caused sue to different causes like a family history, allergy, due to a malfunctioning of the immune system, etc. For a rash, age is no bar and it can affect the elderly, infants, and even pregnant women. Here are 7 probable reasons you’re suffering from a rash:
What are the common causes of a rash?
1. Contact dermatitis
Contact dermatitis is a type of localized rash or irritation of the skin due to direct contact with a substance. It is of two types – irritant and allergic
Irritant dermatitis occurs when you come into contact with acidic or alkaline substances and the reaction looks like a burn. Irritants like soaps and detergents, fabric softeners, and other chemicals are commonly known to cause this kind of dermatitis. Apart from that, products like cement, hair dyes, pesticides, some shampoos, or even rubber gloves can cause irritant dermatitis.
When you come into contact with substances to which you have become ultrasensitive or are allergic, it can cause allergic contact dermatitis. For example, you may get a rash when you are exposed to substances such as adhesives, rubber or latex, perfumes, clothing, cosmetics such as nail polish, lipsticks, and hair dyes, metals used in jewelry or watch straps or metal zips. Plants such as poison ivy, poison oak, poison sumac, and other plants too can cause a rash if you are allergic to them.
2. Seborrheic dermatitis
Don’t be intimidated by the name. It is one of the most common and harmless but bothersome skin rashes that appears in patches of redness and scaling – dandruff; but only if it appears on the scalp. Sometimes this type of rash appears around the eyebrows, eyelids, mouth, nose, the trunk and behind the ears.
The exact cause of seborrheic dermatitis is not known, but scientists believe it could caused due to any of the following reasons:
- Irritation of scalp due to over shampooing, frequent combing, use of certain cosmetic products, use of alcohol-based lotions
- Irritation from a fungus called Malassezia
- Dry skin or build-up of oil and dirt on the scalp (possibly due to infrequent shampooing)
- Stress, fatigue
- Lack of nutrients such as zinc, B-vitamins, some type of fats
- Weakened immune system or nervous system problems
- Genetic
3. Atopic dermatitis
Atopic dermatitis is a chronic condition that causes itchy, inflamed skin. It is a disease of the whole body that manifests in the skin because of an overactive immune response brought on due to environmental factors.
Scientists think atopic dermatitis occurs because of an inherited abnormality of the skin, called ‘skin barrier defect’. This barrier defect increases the permeability of the skin and reduces its antimicrobial function. The loss of the skin barrier means water is lost, irritants such as soaps, detergents, dirt, and allergens such as pollen, microbes, dust-mite, etc. tend to penetrate the skin.
Also, an imbalance of the immune system causes the inflammation, which exacerbates (makes worse) the barrier defect causing infections that are very difficult to control.
In short, the following factors can cause atopic dermatitis:
- Imbalance in immune system
- Dry skin due to harsh winters, bathing in very hot water, low humidity, chlorine in swimming pools
- Irritants such as soaps, detergents, dusty environment and some cosmetics
- Food allergies and environmental allergens
- Bacterial, viral, and fungal infections
- And finally, stress
4. Other disorders
Apart from atopic dermatitis, the following disorders can cause a rash too:
- Psoriasis: An inherited, autoimmune condition in which a rash appears that looks like red, scaly, itchy patches over joints and along the scalp.
- Impetigo: Caused by the bacterium called Streptococcus (strep) and Staphylococcus(staph), this rash occurs as red sores that turn into blisters, ooze, and then crust over.
- Shingles: Also called herpes zoster, it is a painful, blistering skin rash caused by the virus varicella-zoster virus, the virus which causes chicken pox too. Red patches followed by blisters that form small sores that begin to dry and form crusts. The crusts fall off in 2 to 3 weeks.
- Measles, rubella and scarlet fever do manifest as a rash.
5. Autoimmune disorders
Certain autoimmune diseases cause symptoms of rash. These include:
- Lupus erythematosus: This autoimmune disease that leads to chronic inflammation. The rash appears associated with this condition appears in the shape of a butterfly and is known as a ‘butterfly rash’. The rash is seen most often over the cheeks and bridge of the nose, but can be widespread and usually gets worse in the sunlight.
- Juvenile rheumatoid arthritis: Is a chronic autoimmune disease resulting in joint pain and swelling. The rash associated with this condition appears on the trunk (or torso), hands and legs and tends to appear and disappear with fever.
- Kawasaki disease: This condition is caused due to inflammation of the blood vessels, and commonly occurs in children. The distinction of rashes caused due to Kawasaki diseases if that the rash appears in the middle of the body and is not blister-like.
6. Skin rashes during pregnancy
Pruritic urticarial papules and plaques of pregnancy (PUPPP) are the most common pregnancy-specific skin rashes, that occur in more than 30 percent of pregnancies. There is no specific treatment for PUPPP, but it is not associated with any adverse pregnancy outcomes.
The characteristics of a PUPPP-associated rash are:
- Intensely itching bumpy rash
- Develops in the third trimester
- First appears on the abdomen (generally)
- More common with first pregnancies and multiple pregnancies
- Typically resolves one to two weeks after delivery
Although it is one of the commonest rashes occurring in pregnant women, scientists are yet to conclusively determine the cause of this rash. One theory is that PUPPP is related to stretching of the skin on the abdomen, especially in women with multiple pregnancies. Somehow the rash develops as a sort of allergy to stretch marks and spreads elsewhere on the body. Another theory links the condition to the maternal immune system and fetal cells.
7. Medication causing rash (drug rash)
Drugs can cause rashes, some of the most common rash is due to:
- An allergic reaction to medication
- Hypersensitivity to sunlight caused by medication
- Corticosteroids, anabolic steroids, progestogens, bromide, iodide, lithium, phenytoin that cause acne (red bumps on face, neck and chest).
- Sulpha drugs, barbiturates, isoniazid, penicillin, and phenytoin cause exfoliative dermatitis (red scaly skin almost on the whole body).
- Antibiotics and phenolphthalein (found in certain laxatives) that cause dark red or purple rashes that reacts at the same site.
- Aspirin, certain drug dyes, penicillin, and other drugs may cause hives.
- Antibiotics, high blood pressure drugs, and contrast dye could cause flat, red rash that may include pimples similar to the measles.
- Some anticoagulants and diuretics may cause purple areas on the skin, especially legs.
- Sulpha drugs, barbiturates, penicillin, and certain drugs used for seizures and diabetes may cause blisters or a hive-like rash on the lining of the mouth, vagina, or penis. This type of rash is called Stevens-Johnsons syndrome.
Insect bites and stings could also cause rashes but these are not long term. Simple rashes would improve with gentle skin care and by avoiding the triggers. Applying hydrocortisone 1% will soothe most simple rashes. Calamine medicated lotions can also do the trick for contact dermatitis. For persistent rashes consult a doctor.
