Hives

What are hives?

Hives are a rash caused by an overload of the chemical histamine. They are also clinically known as urticaria. They can be acute and short-term, lasting less than six weeks, or chronic and long-term.

Another type of hives, known as ‘urticaria vasculitis’, causes blood vessels within the skin to inflame. In this case, the rash can last longer than a period of 24 hours and can be extremely painful and cause bruising of the skin.

Hives can be distressing and disrupt daily life and sleep;it’s important to see your doctor if your symptoms don’t improve within 48 hours.

Who gets hives?

Just about anyone can get hives, but people with allergies are more likely to develop them, usually when exposed to an allergen. They are also more common in the 20-40 years age group, and hives are twice as common in women. ^[1]

Acute hives are also more common in adolescents and children, impacting about 3% of children, and in those with atopy.

How common are hives?

Hives are quite common, affecting up to 20% of the population over their lifetime. ^[2] The peak age for getting hives is between 20 to 40 years old.

What causes hives?

Acute hives usually develop in response to a trigger, like being exposed to something you’re allergic to, or by catching a viral infection like a cold or flu.

We don’t always know why chronic hives happen, but it’s often a combination of several factors. Hives occur when something triggers the body to produce a high level of histamine which is sent to the skin, causing your blood vessels to open up, swell and itch.

Sometimes hives can be caused by an allergic reaction to particular foods, such as milk, eggs or shellfish. Hives can also be brought on by reactions to insect bites, latex, particular drugs like Penicillin and vaccines. They can also appear in response to the skin coming into contact with something, like pressure or an irritant. Common examples include hot or cold water, sitting or lying down for long periods of time and even wearing tight clothes.

What are the symptoms of hives?

The most common symptom of hives is a red and itchy rash. This rash can affect any area of skin on the body. Small areas, which are raised from the surface of the skin (called weals), look like blisters and cause itching. Each weal is usually around 1-2cm across, but can vary from case to case.

Some people may experience a small cluster on one part of the body, but in other cases, weal’s can form over different parts of the body, and can be separate or join up to form bigger ones. They are often round, but can take other shapes as well.

Can hives lead to other problems?

Most people with hives don’t suffer from any other side effects. However, in some cases a condition called ‘angio-oedema’ can appear at the same time as the hives. This condition causes fluid to leak into deeper tissue underneath the skin causing it to swell. This swelling can appear anywhere on the body but is more common on the lips, eyelids and genitals.

If you have hives, you should try not to scratch them. If you break the skin, you risk it becoming infected or scarring. Hives can be distracting or painful but most cases are mild. In severe cases, the tongue and throat can become swollen and can cause difficulty with breathing which would need immediate medical attention.