Hives

Hives

What are Hives?

Hives (otherwise known as Urticaria) is characterised by circular red, raised and itchy welts on the surface of the skin. The welts are caused by inflammation of the skin and are one of the most common symptoms of an allergic reaction.1 The Australasian Society of Clinical Immunology and Allergy (ASCIA) estimates that around 1 in 30 children and 1 in 5 adults will experience transient symptoms of hives. However, around 1 in 1000 adults experience chronic or recurrent urticaria, which may have a significant impact on their quality of life.2 The rash may occur anywhere on the body, but is most commonly found on the trunk, throat, arms and legs. The welts may vary in size from relatively small to the size of a dinner plate. They generally form in clusters, with one batch getting worse as another begins to get better.3 Individual hives may last anywhere from 30 minutes to 36 hours.4

Causes

Hives can be due to several different causes. The most common cause of acute hives (where the rash lasts for less than six weeks) is an allergic reaction. The substance responsible for the reaction, known as an allergen, may include animal dander, insect venom (such as bee or wasp stings), foods, medicines and pollen. Occupational exposure to allergens is also a common cause of hives, as the more often an individual is exposed to common allergens, the more likely they will develop an allergy to them. For example, bakers often develop allergies to yeast, flour or grains.5 For some people, hives may also be triggered by physical and emotional causes. These include exercise, sweating, sunshine, heat, cold temperatures and emotional stress.6 They may also appear in response to antibodies produced by the immune system, for example in the case of an infection, such as a cold or flu. Chronic hives (where the rash lasts for longer than six weeks) can be caused by an underlying disorder of the immune system.7 In one third of cases, however, the cause of hives is never identified.8

Symptoms

Hives are characterised by red, raised circular welts on the skin. They may look like mosquito bites, with a red outer rim and a white centre. These welts usually itch and appear in clusters. As one cluster appears, so another tends to get better. An individual welt will usually last for approximately 24 hours, with the attack as a whole lasting anywhere from a few days to weeks.9 Urticaria caused from contact with an allergen, for example by animal saliva, is usually short lived and affects only a small area. Reactions to inhaled allergens, such as animal dander, are almost always associated with nose and eye symptoms. Hives that occur on a daily basis, whether for a few days or weeks, are rarely due to an allergy.10

Treatment

Mild outbreaks of hives may not need treatment and will clear up within a few days on their own. You can reduce the symptoms of mild hives by applying a cool compress to the rash and wearing loose clothing. Try to minimise vigorous activity and avoid irritation of the affected area.11 If the cause of the hives has been identified, avoid the causative factors as much as possible. Avoid sunlight, heat and hot showers, all of which tend to exacerbate hives.12 Moderate symptoms may require treatment with an antihistamine medication, such as Telfast. See your doctor if you have severe hives, or if the rash continues to appear for several days. Seek emergency medical attention if you have an outbreak of hives and feel lightheaded, have difficulty breathing or feel that your throat is swelling.13