Itch is the most common presenting symptom to a dermatologist. It is an uncomfortable, irritating sensation that creates an urge to scratch that can involve any part of the body.
Common causes of this symptom
Itching can have external causes that aren’t due to underlying disease. Examples include hair regrowth, sunburns, insect bites, skin infections, contact allergic dermatitis, dry skin or healing wounds.
Itchy skin can be a symptom of an underlying illness.
- These include liver disease, kidney failure, iron deficiency anemia, thyroid problems and certain cancers, including multiple myeloma and lymphoma.
- Urticaria, Atopic and Seborrheic dermatitis
- Psoriasis, Dermatitis herpetiformis
- Drug reactions
- Nerve disorders, as in after shingles or meralgia parasthetica are other reasons.
- Stress and anxiety can affect your nervous system and cause sensory symptoms like burning or itching of the skin, with or without visible signs. Psychiatric illnesses like depression or obsessive compulsive disorder too can cause itchy skin.
- Itching, occasionally, can be seen in later stage of pregnancy.
Some of the major causes:
Hair Regrowth
After removal of hair from genital area and near folds, the growing stub of hair may cause a lot of itching and discomfort.
Soothing lotions and moisturising the area helps to tide over this phase of re-growth.
Sunburns
Prolonged sun exposure especially on beaches or high altitude often leads to itching and burning on directly exposed parts of the skin on face, neck, shoulders and forearms.
Antihistaminics, analgesics and soothing creams are recommended.
Prevention with sunscreens is ideal.
Dry Skin
Itching can be without a rash, especially as we get older due to dry skin or underlying conditions like hypothyroidism, menopausal skin changes and sjogrens disease. Anything that further dries your skin – such as overuse of soaps, antiperspirants, perfumes, or hot baths – will make the problem worse. Dehydration, sun exposure, smoking, and stress also may cause dry skin. Dry skin itches because it is irritated easily.
Skin Infections – are common in children, in those with poor hygiene, in diabetics and in immune-suppressed adults
- Fungal – commonly seen during humid months and mainly afflicting folds of the skin in those with poor hygiene,
Various dermatophytes or candida are common causes,
Presents as annular scaly or reddish patches. Clinically dermatophyosis are classified according to the site involved.
Fungal infections apart from clinical features are diagnosed with help of Woods lamp and microscopic examination of skin scales in 10-20% KOH preparation and or culturing in sabourads dextrose agar.
Patient with itch showing above signs should see a doctor immediately. Self medication especially with steroid containing creams should be avoided. Needs oral and topical antifungal treatment for at least a month,
Maintaining good hygiene and wearing appropriate clothing and footwear can prevent recurrences.
- Bacterial – Pyoderma is caused by pus producing organisms like Stapyloccus aureus or Streptococcus group A. A pus filled eruption with or without discharge and crusting is the basic lesion in pyodermas.
Following are various types of pyoderma
- Impetigo – small blisters with pus filled fluid spreads and ruptures to leave erosions and crusts,
- Ecthyma – ulcerated lesions with thick adherent crust which on removal bleeds,
- Erythrasma – well circumscribed superficial dry brownish patches with scaling near folds,
- Folliculitis – multiple superficial pus filled lesions on legs or elsewhere,
- Furuncle – Deep hair root infection with nodulo-pustular presentation,
- Carbuncle – this is a large indurated nodular lesion with multiple openings, often an indicator of poorly controlled diabetes or Being on long term steroid medications,
- Sycosis barbae – multiple pustules in beard area,
- Cellulitis – a warm tender swelling usually on one of the legs and accompanied by marked constitutional symptoms,
- Paronychia – painful and itchy swelling of nail folds, and
- Hideradenitis Suppurativa – firm nodular and ulcerated lesions with pus discharging openings
The last three are more painful and may not be very itchy.
Pyodermas may be secondary to other skin conditions like injury, eczemas, burns, etc.
While impetigo can be treated with topical anti-bacterial agents, carbuncles and hideradenitis suppurativa may need invasive and prolonged systemic treatment. For secondary pyodermas, treatment of predisposing condition is essential.
- Viral Infections Chicken pox, and other viral exanthema eruptioms may be associated with itching in initial stage. They are accompanied with fever and other constitutional symptoms.
- Mite – It is commonly transferred from contact with affected person or animals.
It presents with generalised nocturnal itch below neck with more than one family member affected in scabetic infestation.
The skin eruption in scabies is typical and classical lesions can be seen in finger webs, folds and genital areas.
It responds well to topical anti-scabetic application.
- Lice – Afflicted children in school and those with poor hygiene are a common source of this infestation,
Identifying the louse on the skin surface confirms the diagnosis
There are three types
Head louse is commonest in children and their close contacts and nits and louse can be observed on their scalp
Body louse affects those with poor hygiene and bed ridden with itching all over
Pubic louse cause itch below waist area and may be sexually transmitted
Perianal itching can be related to hookworm or pinworm infestation. Generalised itching can also be related to parasites such as threadworms infestation, insects such as bedbugs and mosquitoes.
Allergies
Allergy is an altered response by the human body to a variety of agents
- External reasons include irritation with chemicals, soaps, clothing, insect bites, contact with certain plants like parthenium, etc. The site of involvement usually helps to point the incriminator.
- Hives may be due to various reasons and may need prolonged treatment. Transient red and swollen patches may rarely present with mucous membrane involvement with swollen lips and breathlessness. Acute allergy to food, pollens, house dust and mites, cotton, pet animals, drugs, etc. can be identified with allergy tests. Specific triggers do not cause chronic urticaria, which can make allergy tests unhelpful. Hives can cause uncomfortable itching and be painful, but they are not contagious.
- Drug allergy usually shows up immediately after certain drugs. It may show up as localised blisters or symmetrical rash all over the body. Allergic rash to certain medicines may show up even after four weeks.
- Atopic dermatitis may be seen in more than one family member and its onset in early life and typical distribution of lesions assist in diagnosing. There may be associated asthama or allergic sneezing and rhinitis is self or in other family members.
- Seborrheic dermatitis seen after puberty age has itchy lesions in seborrheic areas.
Other causes
Uremia is a broad syndrome that occurs when the kidneys are severely damaged and cannot filter toxins from the body. With uremia, itching tends to be worse at night. It most commonly affects the back, arms, and abdomen. Psoriasis lesions are mildly pruritic and the classical scaly patches help in diagnosing and treating specifically. Shingles with a dermatomal distribution of grouped tiny blisters should be treated early with anti-virals to prevent complications.
Psychological
People may experience an itching feeling that has no physical cause. Some mental health conditions can make a person feel as if their skin is crawling, which creates an urge to scratch. Neither skin lesion, nor a crawling insect can be detected on examination. Excessive scratching though, can lead to skin damage.
Written by Dr. Jawahar Mansukhani.
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