Itching, also known as pruritus is a sensation that causes the desire or reflex to scratch. Itch is a major somatic sensation, along with pain, temperature, and touch.
Recent studies have suggested similarities between itch and pain.
Both are unpleasant sensory experiences but the behavioral response patterns are different. Pain creates a withdrawal reflex, whereas itch causes a scratch reflex.
Unmyelinated nerve fibers for itch and pain both originate in the skin.
Skin serves as a barrier, protecting the inside of the body.
Cells of the immune system that protect the body and skin from viruses, bacteria, and other hidden threats.
Any local reaction can trigger a rash or dermatitis and cause itching.
Itching could also be caused by a more serious condition such as liver disease or kidney failure.
Itching can affect whole body or only in specific areas.
Itch generates stimulus of a foreign object underneath or upon [insect] the skin and also the urge to remove it. [scratch reflex].
Itching is generally relieved by scratching.
However, in some cases, the pleasure associated with scratching may lead to compulsive nature of itch and scratching.
Causes of Itching
- Lice infestation
- Cutaneous larva migrans
- Herpes rash
- Varicella – i.e. chickenpox, prevalent among young children and highly contagious
- Any other infection causing skin rash
- Swimmer’s itch
- Contact dermatitis due to allergic reaction to contact with specific chemicals,
- Insect bites [mosquitos]
- Punctate palmoplantar keratoderma
- Inflammatiory skin conditions
- Athlete’s foot
- Scab healing
- Growing scar
- Emergence of moles, pimples, and ingrown hair
- Xerosis or dry skin
These medical disorders can cause itching
- Diabetes mellitus
- Jaundice and cholestasis
- Malignancy [Lymphoma or Hodgkin’s disease]
- Polycythemia, which can cause generalized itching due to increased histamines
- Psychiatric illness [psychogenic itch]
- Uremia [uremic pruritus]
- Drugs [Activate histamine (H1) receptors or trigger histamine release]
Related to pregnancy
- Gestational pemphigoid
- Intrahepatic cholestasis of pregnancy
- Pruritic urticarial papules and plaques of pregnancy (PUPPP)
- Changes in hormonal balances associated with aging
Types of Itching
It is also called pruritoceptive and and can be induced by a variety of stimuli. The primary afferent neurons responsible for histamine-induced itch are unmyelinated C-fibres.
Itch receptors are found only on the top two skin layers, the epidermis and the epidermal/dermal transition layers. Sensitivity to pruritic stimuli is evenly distributed across the skin.
Neuropathic itch can originate at any point along the afferent pathway as a result of damage of the nervous system.] Examples of neuropathic itch in origin are brachioradial pruritus, brain tumors, multiple sclerosis, peripheral neuropathy, and nerve irritation.
Neurogenic itch is itch induced centrally but with no neural damage. It is is mostly associated with increased accumulation of exogenous opioids.
It is found in psychiatric disorders such as tactile hallucinations.
A variety of over-the-counter and prescription anti-itch drugs are available. Some plant products have been found to be effective anti-pruritics, others not. Non-chemical remedies include cooling, warming, soft stimulation.
Treatment of Itching
The treatment plan will depend on the cause of itching. The mainstay of therapy for dry skin is maintaining adequate skin moisture and topical emollients.
For conditions like eczema, dermatitis, or hives, corticosteroid creams.
Oral antihistamines are common anti-allergy medications.
Fungal infections can be treated with antifungal treatment, topical and systemic.
Topical antihistamines can relieve itching from insect bites
For itch due to renal failure phototherapy may help.
Drugs Used in Itching
Drug for Itching belong to following classes generally
- Mint oil
- Crotamiton (for scabies)
- Local anesthetics [ benzocaine topical cream]
Home remedies for Itching
Following home remedies may help reduce itching:
- Moisturizing cream application at least once or twice each day
- Applying an anti-itch cream, such as hydrocortisone cream
- Applying a cool, wet compress to the affected area
- Lukewarm bath
- Use mild soaps
- Unscented laundry detergent
- avoiding substances that irritate the skin or cause an allergic reaction such as nickel, jewelry, and wool
The most important self-care measure is to avoid scratching. Scratching can ultimately lead to further inflammation and damage to the skin and can worsen the itching.
Common Conditions Causing Itching
Dry skin is one of the most common causes of itchy skin. Hot or cold weather with low humidity, as well as washing too much may lead to dry skin.
The condition is more common with aging though any age group may be affected.
The skin may be rough, gray or ashy looking and cracked.
A good moisturizer can usually help to repair dry skin.
Eczema, or atopic dermatitis, is the most common cause of skin rash in children and over all common cause of itching.
Eczema often improves as the children grow up.
Allergic reactions and skin irritants cause a red, itchy rash that can include small blisters or bumps.
Allergic reactions can be triggered by encounter with allergen in the environment. A clothing, pets, chemicals, soaps, and substances such as poison ivy or cosmetics may lead to allergies.
Also called urticaria, hives are a skin inflammation caused by the release of a chemical in the body called histamine. This release causes small blood vessels to leak which causes the skin to swell.
Hives, or urticaria, may or may not indicate an allergic reaction.