Understanding hives and other allergies

My back was very itchy recently. After scratching the affected spot, I looked in the mirror and saw that I had multiple raised, red spots on my skin. My wife said it was 'hives'. What are hives?

Hives are also known as urticaria. They look like pale red bumps, patches or weals on your skin. They usually appear suddenly, and are mostly caused by the body's allergic reaction to something that you are allergic to.

However, they can be caused by other things.

They can appear anywhere on your body, including your tongue, ears and lips.

Hives are itchy, and there are some which may also cause burning or stinging sensations. Sometimes, they may join together to form a large red area that is raised. These are known as plaques.

They usually disappear within one day, but some hives may last for days or even weeks.

What causes hives?

Hives are caused by allergic reactions that our bodies have to certain foods, dyes, chemicals, insect bites and stings, medicines or infections. Some diseases may also give rise to hives.

These substances are called allergens.

When you are allergic to any of these, your body releases something called histamine.

Histamine causes your blood plasma to leak out of the small blood vessels on your skin, leading to these raised areas or bumps.

The most common foods that can cause hives are nuts (including almonds and peanuts), fish, prawns and some types of seafood, eggs, milk, wheat and fresh berries. Fresh foods are known to cause more hives than cooked food.

The medicines most cited to cause hives are aspirin and the NSAIDs (non-steroidal anti-inflammatory medicines).

Why do hives last for such a long time?

Hives can be divided into several different types:

Acute urticaria - these last for less than six weeks. These are the ones that are most usually caused by foods, medicines and insect bites.

Chronic urticaria - these last for more than six weeks. The causes are more difficult to identify and may include certain types of diseases like autoimmune diseases, chronic infections and even cancer.

Physical urticaria - this is caused by direct stimulation of your skin. Usually attributed to extreme heat and cold, sun exposure, sweating, certain types of clothes material, exercise and others. This usually occurs one hour after exposure.

Dermatographism - these form after you firmly stroke or scratch your skin.

In what other ways can allergies manifest?

Allergic symptoms usually affect one part of the body or another. When it affects your nose, you may sneeze or have a runny nose. You may also cough.

Allergies can be classified according to severity.

Mild allergic reactions may cause hives, rash, itchy or watery eyes and congestion in the nose. Mild reactions tend to be confined to part of your body only.

Moderate allergic reactions may include itchiness and difficulty breathing. (Such as asthma being triggered by pollen.)

Severe allergic reactions include anaphylaxis, which can progress within minutes to include your whole body.

You may have various degrees of swelling everywhere on your body, as well as difficulty in breathing and swallowing. You may have abdominal pain, vomiting and diarrhoea. You can progress to mental confusion.

Severe allergic reactions are life-threatening and you must go to a doctor immediately, preferably the emergency department of a hospital, depending on how severe your symptoms are, as they would have the necessary equipment to intubate you.

Can hives be treated or do I just have to wait for them to go away on their own?

Hives can certainly be treated. Of course, if you know what allergen has caused it, it's best that you stay away from it the next time.

If you can't eat nuts, then avoid all foods with nuts in them. If you eat out, ask the waitress if the dish you ordered has nuts in it first.

If you can't wear certain jewellery or watches because of the nickel in them, then don't wear anything containing nickel.

You can take antihistamines as these will combat the histamine that is being released in your skin. For severe cases, you can go to a doctor, who may give your steroids.

Meanwhile, bathe in lukewarm water as hot water will only exacerbate your hives. Use gentle soap that is hypoallergenic. You can apply a cool, wet compress to the affected area. Try to keep cool at all times.