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urticaria: (also known as hives, weals, or nettle rash) is a superficial…
urticaria: (also known as hives, weals, or nettle rash) is a superficial swelling of the skin (epidermis and mucous membranes) that results in a red (initially with a pale centre), raised, and intensely itchy rash.
Causes
Chronic urticaria
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spontaneous-idiopathic, but can be aggravated by heat,stress, drugs,viral
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inducable- caused by physical stimulus e.g. cold, heat, aquagenic, cholinergic etc
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Acute Urticaria
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response to trigger eg allergen, foods, viral, stings
The release of histamine and other inflammatory mediators (such as leukotrienes and prostaglandins) from activated mast cells results in the characteristic pruritus, vascular permeability (leading to plasma leakage from the capillary into the skin), and oedema
Presentation
Chronic urticaria-regular episodes presenting for more than 6 weeks, fluctuating in intensity and may disappear in months or even years. Maybe associated dermographism.
Angioedema more often localised. It commonly affects the face (especially eyelids and perioral sites), hands, feet and genitalia. It may involve tongue, uvula, soft palate, or larynx.
Acute urticaria- Urticarial weals can be a few millimetres or several centimetres in diameter, coloured white or red, with or without a red flare. Each weal may last a few minutes or several hours and may change shape. Weals may be round, or form rings, a map-like pattern or giant patches
Diagnosis
Symptom diary-Consider assessing the severity of urticaria using a validated stool, such as the Urticaria Activity Score (UAS7).
Identify and manage the underlying causes/trigger factors of urticaria, where possible
Skin prick tests and radioallergosorbent tests (RAST) or CAP fluoroimmunoassay may be requested if a drug or food allergy is suspected in acute urticaria.
There are no routine diagnostic tests in chronic spontaneous urticaria apart from blood count and C-reactive protein (CBC, CRP), but investigations may be undertaken if an underlying disorder is suspected.
Hx, Family Hx, physical examination
Treatment
Offer a non-sedating antihistamine (for example cetirizine, fexofenadine, or loratadine) for up to 6 weeks
If symptoms are severe, give a short course of an oral corticosteroid (for example prednisolone 40 mg daily for up to 7 days) in addition to the non-sedating oral antihistamine.
Symptoms improve: consider as required treatment or thought to be persitent or recurring consider longer courses up to 6 months
if inadequate response consider increasing antihistamine up to QDS or switch to an alternative antihistamine. Prescribe a topical antipruritic treatment (such as calamine lotion or topical menthol 1% in aqueous cream) to relieve itch. Prescribe an additional sedative antihistamine (such as chlorphenamine) at night, if itch is interfering with sleep..
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Referral
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A clinical psychologist for people whose symptoms are adversely affecting their quality of life, for example causing significant social or psychological problems.
Complications
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angio-oedema can co-exist with chronic urticaria and may lead to airway obstruction, and anaphylaxis (a life-threatening, generalized or systemic hypersensitivity reaction) may rarely occur in people with urticaria