Acute urticaria (hives)

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What is acute urticaria?

Acute urticaria (AU) are distinct skin conditions characterized by itchy welt or wheals appearing as flat-topped, round, annular or geographic pale-pink-red papules or plaques typically evanescent, resolving and disappearing within 24 to 48 hours.

In rare cases the AU manifestations last longer. If the weal lasts longer than six weeks it is classified as chronic urticaria (CU). It is found that 20% to 30% of the cases of acute weals recur and some evolve into chronic cases. Au is one of the common medical condition known and its life time prevalence is 10% -25%.

The weals/papules can suddenly appear on any area of skin. Adjoining papules may join together to form larger swollen areas known as plaques. The weals may fade gradually and the skin may become normal in a short time. As some papules fade some fresh papules may also appear. The associated itching and the blotched appearance of the affected skin is very distressing.

In some cases AU is associated with angioedema. Angioedema often causes swelling of eyelids, lips and sometimes tongue. The puffiness may also occur in the face, ears, hands, feet and genitalia. Usually the swellings do not cause itching and are painful. The swelling occurs in the deeper layers of skin. Along with cutaneous manifestations of acute weals some people get extra cutaneous manifestations such as body ache, joint pains and gastrointestinal tract problems. This is probably due to systemic effect of inflammatory mediators released by mast cells present in the skin as well as by the local mast cells.

Causes of acute urticaria

The basic cause of all types of urticaria is activation of cutaneous mast cells and release of histamine and other mediating chemicals of inflammation. Histamine by activating the endothelium and dilating capillary venules causes blood plasma to leak into the interstitial spaces. This causes edema, reddening, warmth, itching and pain.

Possible triggers of Acute urticaria

In children dominating causative factors are viral infections, medication intolerance and food allergies. In adults also acute infections, food allergies and chemical allergies play a triggering part. Other triggers include insect stings, exposure to cold, exposure to sun, contact with chemicals, inhalation of allergens, fish, shellfish, nuts, egg, cow's milk etc.  In half of all the cases, acute urticaria are idiopathic, appearing spontaneously without any known provocation.

Treatment for acute urticaria

As acute urticaria is self-limiting it is treated symptomatically to completely suppress the clinical manifestations. Taking antihistamines eases itching and the condition resolves after some time. Treatment regimen include glucocorticoids or non-sedating antihistamines alone or in combination depending upon the requirement.

Risks involved in acute urticaria

Anaphylaxis causes difficulty in breathing and asphyxiation. When AU is associated with anaphylaxis, it is life-threatening and is a medical emergency. Anaphylaxis is rapid in onset and may cause death. The first-line therapy for anaphylaxis is immediate intramuscular administration of epinephrine and hospitalization for further treatments until recovery.

Related topics of interest:
Chronic urticaria treatment
Types of urticaria

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References:
1.Marcus Maurer and Jürgen Grabbe, Urticaria: Its History-Based Diagnosis and Etiologically Oriented Treatment, Dtsch Arztebl Int. 2008 June; 105(25): 458–466. PMCID: PMC2696901