Itching is an important part of most skin diseases. In some, like atopic dermatitis, neurodermatitis and prurigo nodularis, pruritus could be very severe and disabling. Itching is typically present during the night in scabies, when the itch mites start moving around.
Itchy skin can be caused by almost all the skin diseases. Skin allergies including eczemas, food and drug allergies, infections, infestations, dry skin and some hereditary and autoimmune disorders all produce pruritus of varying degree during their disease course. Described below are the commonest skin diseases where itching is a prominent symptom.
Itching in Dry Skin
Dry skin is one of the commonest causes of itchy skin. Use of harsh soaps, heredity, winter dryness all contribute to excessive dry skin. Itching varies from mild to moderate severity and is intermittent in nature.
Itchy Skin Caused by Allergic Dermatoses
Skin diseases caused by allergy to a variety of chemical and biological agents are almost always accompanied by itchy skin rashes.
- Insect bite reactions. Especially in children, insect bites from mosquitoes and other crawling or flying insects can cause allergic and irritant reactions with moderate to severe pruritus. Bed bugs are a common cause for itchy bumps in both adults and children in crowded, unhygienic conditions.
- Drug reactions. Drug allergies can cause generalized itching, both with and without skin rashes.
- Food allergy. Any food item, including food additives, can cause allergic or toxic skin eruptions with generalized itching. Some food and beverages like beer and shell fish etc may cause itchy palms and soles as well as generalized pruritus. Yeast infested nuts are a main cause for urticaria and generalized itchy skin rashes.
- Urticaria. Itching may be a presenting symptom in urticaria, even before the appearance of the hives or wheals. In many cases, itching is relieved faster; while the wheals keep re-appearing without the itch component for a few more days.
- Aquagenic pruritus and aquagenic urticaria are characterized by intense itching after contact with water.
- Atopic dermatitis. Intense itching is the most important factor which causes the recurrences and exacerbations in atopic dermatitis.
- Contact dermatitis to plants, chemicals, dyes, clothes etc, whether allergic or irritant, causes itching of various intensity. Sometimes itching can present without skin rashes.
- Sun sensitivity. Itching and redness on exposed parts following sun exposure indicates photosensitivity.
Itchy Skin Disease Due to Infections
The following bacterial and fungal infections of the skin can present with skin itch:
- Folliculitis (infection of the hair follicles). Pus filled bumps related to hair follicles present with itching due to the irritation of nerve endings in the vicinity. Pain sensation replaces the itchiness when the infection progresses, though.
- Fungal infections. Scaly, brownish red patches with active margins, mainly on the body folds indicate fungal infections. In children, tinea capitis can affect the scalp and hair. In adults trunk and face are also affected in mistreated cases, especially with topical steroids. Itching is moderate to severe in fungal infections and is a consistent factor throughout the disease course.
Itchy Skin Following Infestations
Itchy skin may result from infestations such as scabies. Typical sites of involvement are the finger webs, inner wrist, elbows, below the breasts and genitals. Itching is severe during night and other family members may also be affected, a typical feature with scabies.
Head lice (pediculosis capitis) is a common cause of itchy scalp in young girls.
Scaly Skin Diseases Associated with Itching
Some scaly skin dieseases can also cause itching.
Dandruff, seborrheic dermatitis and psoriasis: Itchy scalp with scaling and/or redness is a feature of dandruff and seborrheic dermatitis. In severe cases, the itchy rash may involve the face, chest and back as well. Itching is absent in most cases of psoriasis, but some patients complain of mild to moderate pruritus, especially during the eruptive stage.
Lichen planus. Polygonal, pruritic, purplish, papules with a plain or raised surface accompanied by severe itching is characteristic of lichen planus. Mostly found on the flexor aspect of forearms and legs, at times lichen planus may become generalized and also involve the genital and oral mucosae.
Itching in Psychodermatoses or Psychogenic Skin Diseases
Psychocutaneous diseases are sometimes overlooked as an important cause for itchy skin conditions. These skin diseases could be very difficult to treat unless the stress and other psychological disturbances are taken care of properly.
- Lichen simplex chronicus (neurodermatitis). As the name indicates, neurodermatitis is considered a psychocutaneous disorder. Itching in neurodermatitis is increased during stressful periods. The thickened, lichenified plaques are present in easily accessible parts of the body.
- Prurigo nodularis. The intensely itchy nodular eruptions in nodular prurigo may start following insect bites; stress and intense scratching play an important role in maintaining the skin bumps. The itching may be severe enough to interfere with the patient’s day to day activities.
Rarer Skin Diseases with Itchy Skin as a Symptom
Rarer causes for itchy skin include dermatitis herpetiformis, neurofibroma, mastocytosis and immunobullous skin diseases
The diagnosis of skin diseases with itching associated with identifiable skin lesions are easy, though itchy skin disease without rash is a difficult problem to diagnose and treat.
Related Article
- How Does Itching Occur?: How Scratching Relieves the Itch. It would be interesting to know how itching occurs in skin and systemic diseases and how the act of scratching relieves the itch.
Reference
- Patrick Yesudian. Pruritus. IADVL Textbook and Atlas of Dermatology, 1994, Bhalani Publishing House, Mumbai.
- Greaves MW. Pruritus. Rook’s Textbook of Dermatology, 7th Edition, 2004
Disclaimer
The information given in this article is for educational purpose only so that patients are aware of the options available. No diagnosis should be made or treatment undertaken without first consulting your doctor. If you do so, the author or suite101 will not be responsible for any consequences. The images provided are for illustration purpose only.
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