A rash typically refers to the areas of the skin that begin to display an abnormal texture and color. These skin areas look and feel different from the surrounding skin regions. In most cases, a skin rash is a result of an inflammatory reaction that can be triggered under a variety of circumstances. Inflammation can cause the affected skin areas to become red, swollen, warm, and painful. Secondary infections may also occur in these skin areas, resulting in oozing, scaling, and destruction of skin cells.
Itchy Skin Rashes
An itching sensation is distinct from burning and pain sensations that are also caused by inflammation. Whereas burning or pain sensations make us avoid touching the affected skin areas, an itching sensation invites us to scratch the affected skin areas (sometimes vigorously). The itch receptors present in the skin sense the presence of irritants on the skin that may be removed through scratching. Inflammatory chemical signals such as histamine can also stimulate these itch receptors.
A skin rash may not always itch, or itch to the same extent under all circumstances. For example, the skin bumps that occur in keratosis pilaris are not typically itchy. The bumps caused by skin acne usually itch occasionally, whereas the bumps caused by folliculitis are often itchy. Skin rashes caused by allergies (such as hives) itch regularly. In some cases, the severity of the itching sensation may be directly related to the severity of the skin condition or underlying disorder. For example, itching is usually absent in mild cases of psoriasis, whereas itching is quite intense in severe cases of psoriasis.
Causes of Itchy Skin Rash
An itchy skin rash can appear in a host of different conditions. The following are some of the conditions that are typically associated with an itchy skin rash:
Causes of itchy skin rash in infants
Itchy skin rashes in infants may have a variety of appearances, which could be attributed to a variety of causes. For example, the presence of overactive sebaceous glands on the scalp may cause the skin on the scalp to appear greasy, yellowish, and scaly. This condition in infants is commonly referred to as cradle cap. A red colored skin rash is also a frequent occurrence in babies who wear diapers.
Irritation caused by feces and urine, psoriasis, atopic dermatitis, and bacterial or fungal infections are most likely the cause of such diaper rashes in the groin and buttock areas. Skin infections caused by the bacteria, Staphylococcus aureus, may lead to extensive scaling of the skin. This is typically seen in Staphylococcal scalded skin syndrome (abbreviated as SSSS).
Causes of itchy skin rash in children
A variety of childhood diseases can cause different types of itchy skin rashes in children. The itchy skin in these conditions may either display red spots (also called exanthema) or red scaly skin patches. Examples of childhood diseases that can cause the appearance of itchy red spots on the skin include chickenpox, measles, hand, foot and mouth disease, scarlet fever, Kawasaki disease, meningococcal disease, fifth disease, roseola infantum, and a host of viral infections (such as hepatitis B, echo virus, and Epstein Barr virus).
The red spots in these diseases are also accompanied by other symptoms such as headache, fever, heart abnormalities and malaise. Tinea capitis (also known as the scalp ringworm) is an example of a childhood disease that causes red, scaly skin rashes on the scalp. This condition may also be accompanied by patchy hair loss on the scalp. In some children, skin irritation caused by saliva can lead to the appearance of red, scaly skin rashes at the corners of the mouth.
Read more on scalp ringworm.
Causes of itchy skin rashes in pregnant women
In pregnant women, an itchy red rash that consists of bumps may appear on the stretch marks over the abdomen. This rash (also known as polymorphous eruption of pregnancy or pruritic urticarial papules and plaques of pregnancy) usually appears in the last trimester of pregnancy. After delivery of the baby, these rashes clear up on their own.
Causes of itchy red bumps on the skin
Itchy red bumps on the skin may appear in a host of different conditions. Examples of some such conditions include acne, insect bites, razor bumps, malaria, folliculitis, sty, perioral dermatitis, filariasis, dengue, rocky mountain spotted fever, hives, Grover’s disease, and seabather’s eruption.
Causes of itchy lumps, nodules or boils on the skin
Examples of itchy lumps, nodules or boils on the skin include hidradenitis suppurativa, erythema nodosum, nodular prurigo, and furuncle. These itchy bumps may be quite painful (as in the case of furuncle) or ooze out fluid (as in the case of hidradenitis suppurativa). The causes of these lumpy skin rashes include infections, diseases, pregnancy, and side-effects of contraceptives and drugs. In some cases (such as nodular prurigo), the cause is not known.
Causes of itchy red rashes without blisters or scaling
Examples of itchy red rashes that appear without any blisters or scaly skin include hives, pityriasis rosea, dermatomyositis, amyloidosis, and granuloma annulare. Such rashes may also be caused by scombroid fish poisoning, sunburns, and angioedema.
Causes of itchy skin rashes with scaly patches
Itchy skin rashes with scaly patches are most frequently seen in fungal skin infections (such as tinea cruris, tinea pedis, tinea corporis, and tinea capitis). Other causes of scaly and itchy skin rashes include lichen sclerosus and psoriasis.
Causes of itchy red rashes with blisters, crusts, and scaly skin
A variety of infections, diseases, and other conditions can cause itchy skin rashes that are characterized by formation of blisters, crusts, and scaly skin. Examples of infectious causes of such skin rashes include herpes infection, cellulitis, dermatophytid, pityriasis versicolor, impetigo, and paronychia.
Examples of other conditions that may result in such skin rashes include Paget’s disease, palmoplantar keratoderma, dermatitis herpetiformis, actinic prurigo, atopic dermatitis, and scabies. Even contact with certain plants such as poison ivy, nettle, and chrysanthemums may cause itchy skin rashes. Skin contact with jellyfish is also known to cause such skin rashes.
Causes of itchy skin rashes with ulcers
Skin cancers (such as squamous or basal cell carcinomas) and gravitational eczema can cause itchy skin rashes that may be accompanied by ulcers.
Causes of itchy skin rashes on groin, armpits, beard, and scalp
Itchy skin rashes in these areas can be caused by dandruff, seborrheic dermatitis, sebaceous cysts, lice, sexually transmitted diseases, and fungal infections of the skin.
Read more on seborrheic dermatitis.
Itchy skin rashes caused by systemic diseases
Itchy skin rashes can occur in a variety of internal systemic diseases such as celiac disease, Crohn’s disease, renal disease, liver disease, rheumatoid arthritis, lymphomatoid granulomatosis, HIV/AIDS and jaundice.
Read more on HIV skin rash.