Weals Health Dictionary

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Weals: From 1 Different Sources

Or wheals: raised white areas of OEDEMA in the skin with reddened margins, which may result from sharp blows, or accompanied by itching, may be a symptom of URTICARIA.
Health Source: Medical Dictionary
Author: Health Dictionary

Urticaria

The rash produced by the sudden release of HISTAMINE in the skin. It is characterised by acute itching, redness and wealing which subsides within a few minutes or may persist for a day or more. Depending upon the cause, it may be localised or widespread and transient or constantly recurrent over years. It has many causes.

External injuries to the skin such as the sting of a nettle (‘nettle-rash’) or an insect bite cause histamine release from MAST CELLS in the skin directly. Certain drugs, especially MORPHINE, CODEINE and ASPIRIN, can have the same e?ect. In other cases, histamine release is caused by an allergic mechanism, mediated by ANTIBODIES of the immunoglobulin E (IgE) class – see IMMUNOGLOBULINS. Thus many foods, food additives and drugs (such as PENICILLIN) can cause urticaria. Massive release of histamine may affect mucous membranes – namely the tongue or throat – and can cause HYPOTENSION and anaphylactic shock (see ANAPHYLAXIS) which can occasionally be fatal.

Physical factors can cause urticaria. Heat, exercise and emotional stress may induce a singular pattern with small pinhead weals, but widespread ?ares of ERYTHEMA, activated via the AUTONOMIC NERVOUS SYSTEM (CHOLINERGIC urticaria) may also occur.

Rarely, exposure to cold may have a smiilar e?ect (‘cold urticaria’) and anaphylactic shock following a dive into cold water in winter is occasionally fatal. The diagnosis of cold urticaria can be con?rmed by applying a block of ice to the arm which quickly induces a local weal.

Transient urticaria due to rubbing or even stroking the skin is common in young adults (DERMOGRAPHISM or factitious urticaria). More prolonged deep pressure induces delayed urticaria in other subjects. IgE-mediated urticaria is part of the atopic spectrum (see ATOPY, and SKIN, DISEASES OF – Dermatitis and eczema). Allergy to peanuts is particularly dangerous in young atopic subjects. Notwithstanding the many known causes, chronic urticaria of unknown cause is common and may have an autoimmune basis (see AUTOIMMUNE DISORDERS).

Treatment Causative factors must be removed. Topical therapy is ine?ective except for the use of calamine lotion, which reduces itching by cooling the skin. Oral ANTIHISTAMINES are the mainstay of treatment and are remarkably safe. Rarely, injection of ADRENALINE is needed as emergency treatment of massive urticaria, especially if the tongue and throat are involved, following by a short course of the oral steroid, prednisolone.

Angio-oedema is a variant of urticaria where massive OEDEMA involves subcutaneous tissues rather than the skin. It may have many causes but bee and wasp stings in sensitised subjects are particularly dangerous. There is also a rare hereditary form of angio-oedema. Acute airway obstruction due to submucosal oedema of the tongue or larynx is best treated with immediate intramuscular adrenaline and antihistamine. Rarely, TRACHEOSTOMY may be life-saving. Patients who have had two or more episodes can be taught self-injection with a preloaded adrenaline syringe.... urticaria

Dermographism

Abnormal sensitivity of the skin to mechanical irritation, to the extent that firm stroking leads to the appearance of itchy weals. The condition is a form of urticaria. It is most common in fair-skinned people with a tendency to allergic conditions.... dermographism

Wheals

See WEALS.... wheals

Angio-oedema

Skin eruption resembling dermatitis or urticaria. A contact allergy from plants such as poison ivy and primula, various chemicals (red-headed matches), cosmetics (make-up), nail varnish, after-shave, certain drugs and perfumes. Allergic reactions are associated with swollen eyelids, shingles, erysipelas or sinus infections. Fever sometimes present and lesions may take the form of the weals of nettle-rash. A hereditary form is rare but the condition is a frequent reaction to aspirin. Differentiate from eczema.

Alternatives. Tea. Formula. Equal parts: Red Clover flower, Nettles, Clivers. 2 teaspoons to each cup boiling water; infuse 10-15 minutes. 1 cup 2-3 times daily.

Tablets/capsules. Garlic. Echinacea. Blue Flag root. Poke root.

Powders. Formula. Echinacea 2; Juniper 1; Blue Flag root half. Dose: 500mg (two 00 capsules or one- third teaspoon) 2-3 times daily before meals.

Tinctures. Formula. Echinacea 2; Valerian 1; Blue Flag root half. Dose: 1-2 teaspoons in water 2-3 times daily before meals. ... angio-oedema

Weal

A raised bump on the skin that is paler than the adjacent tissue and which may be surrounded by an area of red inflammation. Weals are characteristic of urticaria.... weal

Henoch–schönlein Purpura

(Schönlein–Henoch purpura, anaphylactoid purpura) a common, and frequently recurrent, form of *purpura found especially (but not exclusively) in young children. It is characterized by red weals and a purple rash on the buttocks and lower legs due to bleeding into the skin from inflamed capillaries, together with arthritis, gastrointestinal symptoms, and (in some cases) nephritis. Glucocorticoids are often used for treatment. [E. H. Henoch (1820–1910), German paediatrician; J. L. Schönlein (1793–1864), German physician]... henoch–schönlein purpura

Polymorphic Eruption Of Pregnancy

(PEP) intensely itchy papules and weals on the abdomen (except the umbilicus), upper limbs, and buttocks, usually within the *striae gravidarum; it is also known as PUPPP (pruritic urticarial papules and plaques of pregnancy). It occurs in 1 in 250 first pregnancies late in the third trimester. This condition is harmless to mother and baby, but can be very annoying. It lasts an average of 6 weeks and resolves spontaneously 1–2 weeks after delivery. The most severe itching normally lasts for no more than a week.... polymorphic eruption of pregnancy

Erythema Multiforme

Acute inflammation of the skin, and sometimes of the mucous membranes. The disease can occur as a reaction to certain drugs, or may accompany viral infections such as herpes simplex or bacterial infections such as streptococcal infections. Other possible causes are pregnancy, vaccination, and radiotherapy. Half of all cases occur for no apparent reason.

A symmetrical rash of red, often itchy spots erupts on the limbs and sometimes on the face and the rest of the body. The spots may blister or form raised, pale-centred weals, called target lesions. Those affected may have a fever, sore throat, headache, and/or diarrhoea. In a severe form of erythema multiforme, known as Stevens–Johnson syndrome, the mucous membranes of the mouth, eyes, and genitals are affected and become ulcerated.

Corticosteroid drugs may be given to reduce the inflammation. People with Stevens–Johnson syndrome are also given analgesic drugs and may need intensive care.... erythema multiforme

Strongyloidiasis

An infestation of the intestines by the parasitic worm STRONGYLOIDES STERCORALIS. It is widespread in the tropics. Strongyloidiasis is contracted in affected areas by walking barefoot on soil contaminated with faeces. Larvae penetrate the soles, migrating via the lungs and throat to the intestine. Here they develop into adults and produce larvae. Most larvae are passed in the faeces, but some enter the skin around the anus to begin a new cycle. A person may be infested for more than 40 years.

The larvae cause itching and red weals where they enter the skin. In the lungs they may cause asthma or pneumonia. Heavy intestinal infestation may cause swelling of the abdomen and diarrhoea. Occasionally, an infected person with reduced immunity dies of complications, such as septicaemia or meningitis.

Treatment with an anthelmintic drug, usually tiabendazole, kills the worms.... strongyloidiasis


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