Hives

Urticaria

The torso, arms, legs and throat are the parts of the body most commonly affected.

• Raised welts or bumps on the surface of the skin; they're often accompanied by an itch
• The welts are usually red towards the edges with white centres. They may resemble a mosquito bite but are sometimes much larger, varying in size from just a few millimetres up to 25 cm or more in diameter

A few other factors to consider when it comes to hives are:

• Hives often occur in batches with one cluster improving as another worsens in a cycle that can continue for days. Each individual welt is usually present for less than 24 hours
• The same trigger may cause the symptoms to worsen with each subsequent attack
• Hives that occur in the mouth, tongue and throat are called angioedema, and these can interfere with breathing. If you are suffering from angioedema seek emergency medical care immediately

Hives are usually triggered by an allergic reaction to something you have come in contact with but can also be caused by an infection or insect bite. Histamine is released by the body as a part of the immune system's response to the trigger, and high levels of Histamine can make the skin itchy, swollen and inflamed.

The triggers that may provoke hives include:

• Food allergies, most commonly strawberries, shellfish, nuts (including peanuts), chocolate, soy, eggs and cheese
• Reactions to prescription medicines including antibiotics and aspirin
• Some food additives or preservatives
• Stress can not only be a trigger, it can also make the condition worse
• Insect bites and stings
• Exposure to hot or cold temperatures or items
• Exercise and perspiration
• Pressure on the skin (e.g. from tight clothes)
• Infection, for example with the hepatitis B virus, Epstein-Barr virus (the cause of glandular fever), Candida albicans, or certain bacteria. This is a common trigger in children
• Contact with certain plants (especially stinging nettles) or animals
• Hives may also be caused by an underlying health problem, such as thyroid imbalance or systemic lupus erythematosus

Occasionally, the physiological reaction occurs even though there's no discernable trigger present.

Most instances of hives resolve themselves over four days to a few weeks without treatment, but for more problematic cases consult with your healthcare professional to identify any allergens or underlying health issues that may be triggering the problem.

Your doctor may want to conduct a test such as skin prick or blood tests, or recommend an exclusion diet followed by food challenges to try and pinpoint any food allergies. As it's not generally possible to diagnose patients who are experiencing an allergic reaction, testing may usually only be undertaken when the outbreak is severe or long lasting. 

If a food allergy (or allergies) is identified, take steps to exclude the offending foods from your diet.

Other factors that may aggravate or trigger the condition (and consequently should be avoided) include

• Heat
• Spicy foods
• Aspirin
• Alcohol
• Food colourings such as tartrazine, flavourings such as salicylates, and preservatives such as sulfites
• Tight clothing or belts

Take steps to reduce stress, for example by practising meditation or yoga.

To offer relief during outbreaks try applying cold compresses or have a cold shower, this may help soothe the affected area.

Consult your health care professional if:

• You develop the condition following an insect bite or sting. Or if an outbreak occurs after taking medication or having a blood transfusion
• You experience hives that are accompanied by a dry throat, cough, nausea, dizziness or difficulty in breathing
• Symptoms persist or you have recurring bouts of hives lasting a month or more