Acute Urticaria

What is acute urticaria?

Urticaria (sometimes called hives) is an itchy rash caused by tiny amounts of fluid that leak from blood vessels just under the skin surface. Urticaria is classed as:

• Acute urticaria - if it develops suddenly and lasts less than six weeks. Most cases last 24-48 hours. About 1 in 6 people will have at least one bout of urticaria in their life. It can affect anyone at any age. Some people have recurring bouts of acute urticaria.

• Chronic urticaria - if it persists longer than six weeks. (Chronic means persistent or ongoing.) This is uncommon.
  
  

What does the rash of acute urticaria look like?

The rash usually appears suddenly and can affect any area of skin. Small raised areas called weals develop on the skin. The weals look like mild blisters and they are itchy. Each weal is white or red and is usually surrounded by a small red area of skin which is called a flare. The 'weal and flare' rash of urticaria looks similar to the rash caused by a bee sting.

The weals are commonly 1-2 cm across but can vary in size. There may be just a few but sometimes many develop over various parts of the body. Sometimes weals next to each other join together to form larger ones. The weals can be any shape but are often circular. As a weal fades, the surrounding flare remains for a while. This makes the affected area of skin look blotchy and red. The blotches then fade gradually and the skin returns to normal.

Each weal usually lasts less than 24 hours. However, as some fade away, others may appear. It can then seem as if the rash is moving around the body. The rash may appear quite dramatic if many areas of skin are suddenly affected.

Are there any other symptoms?

• Most people with acute urticaria do not feel 'ill', but the appearance of the rash and the itch can be troublesome.

• In some cases a condition called angio-oedema develops at the same time as urticaria. In this condition some fluid also leaks into deeper tissues under the skin which causes the tissues to swell.

  • The swelling of angio-oedema can occur anywhere in the body but most commonly affects the eyelids, lips and genitals.

  • Sometimes the tongue and throat are affected and become swollen. The swelling sometimes becomes bad enough to cause difficulty breathing.

  • Symptoms of angio-oedema tend to last longer than urticarial weals. It may take up to three days for the swollen areas to subside and go.

• A variation called 'vasculitic urticaria' occurs in a small number of cases. In this condition the weals last more than 24 hours, they are often painful, may become dark red, and may leave a red pigmented mark on the skin when the weal goes.
  

What causes acute urticaria?

A 'trigger' causes cells in the skin to release chemicals such as histamine. The chemicals cause fluid to leak from tiny blood vessels under the skin surface. The fluid pools to form weals. The chemicals also cause the blood vessels to open wide (dilate) which causes the flare around the weals. The trigger is not identified in about half of cases. Some known triggers include:

• Allergies - for example:

  • Food allergies such as allergies to nuts, strawberries, citrus fruit, egg, food additives, spices, chocolate, or shellfish. Sometimes you can develop an allergy to a food even if you have eaten it without any problem many times before.

  • Allergies to insect bites and stings.

  • Allergies to medicines such as penicillin, aspirin, anti-inflammatory painkillers, etc.

• A viral infection such as a cold or 'flu can trigger an urticarial rash in some people. (You 'react' to the virus.) A mild viral infection which causes few other symptoms is probably a common trigger of an urticarial rash that develops without an apparent cause.
• Skin contact with 'sensitizers' causes a local area of urticaria in some people. For example, chemicals, latex, cosmetics, plants, ointments, nettle stings, etc.
• Physical urticaria. This is when a localised rash appears when the the skin is physically stimulated. The most common is called dermographism when a rash develops over areas of skin which are firmly stroked. Sometimes an urticarial rash is caused by heat, cold, emotion, exercise, or strong sunlight.

Is acute urticaria serious?

Usually not. The rash is itchy but normally fades within a day or so and causes no harm. Most people with acute urticaria do not feel too unwell unless they have a cold or 'flu that is triggering the rash. The cause of the rash is not known in more than half of cases and it is commonly a 'one-off' event.

However, urticaria may be more serious in the following situations.

• Food allergy. If a food allergy is the cause then the rash is likely to return each time you eat the particular food. This is more often a 'nuisance' than serious.

• Severe allergies. People who have a severe allergic reaction to peanuts, insect stings, etc, often have an urticarial rash as one of the symptoms. This is in addition to other symptoms such as severe angio-oedema, breathing difficulties, collapse, etc. A severe allergic reaction is called anaphylaxis. But note: most people with acute urticaria feel well and do not have anaphylaxis.

• Chronic urticaria. This means the rash keeps coming and going on most days for six weeks or longer. This is uncommon.
  

Immunotherapy (IT)

Why do we use immunotherapy?

While other allergy treatments (such as antihistamines or corticosteroids) treat only the symptoms of allergic disease, immunotherapy is the only available treatment that can modify the natural course of the allergic disease, by reducing sensitivity to allergens.

How long is the treatment?

A three-to-five-year individually tailored regimen of injections may result in long-term benefits. Recent research suggests that patients who complete immunotherapy may continue to see benefits for years to come. Immunotherapy does not work for everyone and is only partly effective in some people, but it offers allergy sufferers the chance to eventually reduce or stop symptomatic/rescue medication.

Should you get IT?

The therapy is indicated for people who are extremely allergic or who cannot avoid specific allergens. For example, they may not be able to live a normal life and completely avoid pollen, dust mites, mold spores, pet dander, insect venom, and certain other common triggers of allergic reactions. Immunotherapy is generally not indicated for food or medicinal allergies.

Does one size fits all?

Immunotherapy is typically individually tailored and administered by an allergist (allergologist). Injection schedules are available in some healthcare systems and can be prescribed by family physicians. This therapy is particularly useful for people with allergic rhinitis or asthma.

How IT is given?

The therapy is particularly likely to be successful if it begins early in life or soon after the allergy develops for the first time. Immunotherapy involves a series of injections (shots) given regularly for several years by a allergist. The first shots contain very tiny amounts of the allergen or antigen to which you are allergic. With progressively increasing dosages over time, your body will adjust to the allergen and become less sensitive to it. This process is called desensitization.

Hay fever (Allergic rhinitis)

What is hay fever?

Pollen is the name given to the fine powder that is produced by plants, trees or flowers to fertilise other plants, trees or flowers of the same species. Strictly speaking, hay fever is caused by an allergy to grass or hay pollens. Grass pollen is the most common cause and tends to affect people every year in the grass pollen season from about May to July (late spring to early summer). However, the term is often used when allergies are caused by other pollens such as tree pollens. Tree pollens tend to affect people from March to May (early to late spring) each year. Other people may be allergic to weed pollens (including nettles and docks). Weeds tend to pollinate from early spring to early autumn.

Symptoms are due to your immune system reacting to the pollen. Cells on the lining of the nose and eyes release histamine and other chemicals when they come in contact with pollen. This causes inflammation in the nose (rhinitis) and eyes (conjunctivitis). Sometimes the sinuses and throat can also be affected.

Hay fever is also called seasonal allergic rhinitis because symptoms tend to occur at the same time, or in the same season, each year.

What are the symptoms of hay fever?

The symptoms of hay fever can vary from person to person. Some people only have mild symptoms that tend to come and go. Others can be severely affected with symptoms that are present every day during the pollen season.

• Common symptoms - These include a runny and itchy nose, a blocked nose, sneezing, itchy and watery red eyes, and an itchy throat. In some cases only nose symptoms occur, and in some cases only eye symptoms occur.

• Less common symptoms - These are loss of smell, face pain, sweats, and headache.

• Asthma symptoms - Symptoms such as wheeze and breathlessness may get worse if you already have asthma. Some people have asthma symptoms only during the hay fever season. If you have hay fever, you are more likely to develop asthma.

The symptoms may be so bad in some people that they can affect sleep, interfere with school and exams or interfere with work.

How is hay fever diagnosed?

You doctor or nurse can usually diagnose hay fever from your typical symptoms that can occur during the hay fever season. They may also ask if there is a history in your family of hay fever, asthma or eczema.

If hay fever is suspected, your doctor or nurse will usually suggest treatment for your symptoms. If the symptoms respond to treatment, this can help to confirm the diagnosis. In rare cases when the diagnosis is in doubt, your doctor may suggest blood tests or skin prick testing to confirm your pollen allergy

Will it help if I avoid pollen?

It is impossible to totally avoid pollen. However, symptoms tend to be less severe if you reduce your exposure to pollen. The pollen count is the number of pollen grains per cubic metre of air. The pollen count is often given with TV, radio, internet, or newspaper weather forecasts. A high pollen count is a count above 50. The following may help when the pollen count is high:

• Stay indoors as much as possible, and keep windows and doors shut.

• Avoid cutting grass, large grassy places, and camping.

• Shower and wash your hair after being outdoors, especially after going to the countryside.

• Wear wrap-around sunglasses when your are out.

• Keep car windows closed, and consider buying a pollen filter for the air vents in your car. These should be changed at every service.

Desensitization (Immunotherapy)

While other allergy treatments (such as antihistamines or corticosteroids) treat only the symptoms of hay fever, immunotherapy is the only available treatment that can modify the natural course of the allergic disease, by reducing sensitivity to allergens (see section on immunotherapy).