An itch is a sensation that causes a strong desire or reflex to scratch. Itches have resisted many attempts to be classified as any one type of sensory experience. Itches have many similarities to pain, and while both are unpleasant sensory experiences, their behavioral response patterns are different. Pain creates a withdrawal reflex, whereas itches leads to a scratch reflex.
Contact dermatitis is a type of acute or chronic inflammation of the skin caused by exposure to chemical or physical agents. Symptoms of contact dermatitis can include itchy or dry skin, a red rash, bumps, blisters, or swelling. These rashes are not contagious or life-threatening, but can be very uncomfortable.
Antipruritics, abirritants, or anti-itch drugs, are medications that inhibit the itching often associated with sunburns, allergic reactions, eczema, psoriasis, chickenpox, fungal infections, insect bites and stings like those from mosquitoes, fleas, and mites, and contact dermatitis and urticaria caused by plants such as poison ivy or stinging nettle. It can also be caused by chronic kidney disease and related conditions.
Postherpetic neuralgia (PHN) is neuropathic pain that occurs due to damage to a peripheral nerve caused by the reactivation of the varicella zoster virus. PHN is defined as pain in a dermatomal distribution that lasts for at least 90 days after an outbreak of herpes zoster. Several types of pain may occur with PHN including continuous burning pain, episodes of severe shooting or electric-like pain, and a heightened sensitivity to gentle touch which would not otherwise cause pain or to painful stimuli. Abnormal sensations and itching may also occur.
Neuropathic pain is pain caused by a lesion or disease of the somatosensory nervous system. Neuropathic pain may be associated with abnormal sensations called dysesthesia or pain from normally non-painful stimuli (allodynia). It may have continuous and/or episodic (paroxysmal) components. The latter resemble stabbings or electric shocks. Common qualities include burning or coldness, "pins and needles" sensations, numbness and itching.
Aquagenic pruritus is a skin condition characterized by the development of severe, intense, prickling-like epidermal itching without observable skin lesions and evoked by contact with water.
Atopic dermatitis (AD), also known as atopic eczema, is a long-term type of inflammation of the skin. AD is also often called simply eczema but the same term is also used to refer to dermatitis, the larger group of skin conditions. AD results in itchy, red, swollen, and cracked skin. Clear fluid may come from the affected areas, which can thicken over time.
Pruritic urticarial papules and plaques of pregnancy (PUPPP), known in United Kingdom as polymorphic eruption of pregnancy (PEP), is a chronic hives-like rash that strikes some women during pregnancy. Some skin changes are known to occur in people who are pregnant while other skin conditions, or dermatoses, that people have prior to getting pregnant will become altered or symptoms will increase. Pruritic urticarial papules and plaques of pregnancy (PUPPP) is one of many skin conditions that is specific to pregnancy and occurs in about 1 in every 160 (0.625%) of pregnancies.
Prurigo nodularis (PN), also known as nodular prurigo, is a skin disorder characterized by pruritic (itchy), nodular lesions, which commonly appear on the trunk, arms and legs. Patients often present with multiple excoriated nodules caused by chronic scratching. Although the exact cause of PN is unknown, PN is associated with other dermatologic conditions such as untreated or severe atopic dermatitis and systemic causes of pruritus including liver disease and end stage kidney disease. The goal of treatment in PN is to decrease itching. PN is also known as Hyde prurigo nodularis, or Picker's nodules.
Pruritus ani is the irritation of the skin at the exit of the rectum, known as the anus, causing the desire to scratch. The intensity of anal itching increases from moisture, pressure, and rubbing caused by clothing and sitting. At worst, anal itching causes intolerable discomfort that often is accompanied by burning and soreness. It is estimated that up to 5% of the population of the United States experiences this type of discomfort daily.
Aquagenic urticaria, also known as water allergy and water urticaria, is a form of physical urticaria in which hives develop on the skin after contact with water, regardless of its temperature. The condition typically results from contact with water of any type, temperature or additive.
Dermatitis herpetiformis (DH) is a chronic autoimmune blistering skin condition, characterised by intensely itchy blisters filled with a watery fluid. DH is a cutaneous manifestation of coeliac disease, although the exact causal mechanism is not known. DH is neither related to nor caused by herpes virus; the name means that it is a skin inflammation having an appearance similar to herpes.
Hand eczema presents on the palms and soles, and may sometimes be difficult or impossible to differentiate from atopic dermatitis, allergic contact dermatitis, and psoriasis, which also commonly involve the hands. Even a biopsy of all these conditions may not result in a definitive diagnosis, as all three conditions may demonstrate spongiosis and crusting on the hands.
Erosive pustular dermatitis of the scalp presents with pustules, erosions, and crusts on the scalp of primarily older Caucasian females, and on biopsy, has a lymphoplasmacytic infiltrate with or without foreign body giant cells and pilosebaceous atrophy.
Psychogenic pruritus, also known as psychogenic itch or functional itch disorder is pruritus not associated with a dermatologic or systemic cause. More often than not, it is attributed to a psychiatric cause. Psychogenic pruritus is not the same as neuropathic itch though both are conditions which require more research. This condition is not explained well in DSM-V and is typically considered a diagnosis of exclusion. This condition is not well-studied and it is difficult to ascertain as it is seen by both dermatologists and psychiatrists. In order to provide some consensus to this condition, The French Psychodermatology Group have created diagnostic criteria for this condition.
Brachioradial pruritus is an intense itching sensation of the arm usually between the wrist and elbow of either or both arms. The itch can be so intense that affected individuals will scratch their own skin to a bleeding condition.
Linear IgA bullous dermatosis is a rare immune-mediated blistering skin disease frequently associated with medication exposure, especially vancomycin, with men and women being equally affected. It was first described by Tadeusz Chorzelski in 1979 and may be divided into two types:
Uremic pruritus is caused by chronic kidney failure and is the most common internal systemic cause of itching.
Senile pruritus is one of the most common conditions in the elderly or people over 65 years of age with an emerging itch that may be accompanied with changes in temperature and textural characteristics. In the elderly, xerosis, is the most common cause for an itch due to the degradation of the skin barrier over time. However, the cause of senile pruritus is not clearly known. Diagnosis is based on an elimination criteria during a full body examination that can be done by either a dermatologist or non-dermatologist physician.
Topical steroid withdrawal, also known as red burning skin and steroid dermatitis, has been reported in people who apply topical steroids for 2 weeks or longer and then discontinue use. Symptoms affect the skin and include redness, a burning sensation, and itchiness, which may then be followed by peeling.
