An allergy produces an abnormal, negative reaction to a chemical or substance. Allergies occur when the body doesn’t tolerate a certain substance or product in the same way as other people do; the allergen (the substance that produces the reaction) is often completely harmless to most other people.
Allergies are very common in the UK, with 1 in 4 people being affected by an allergy at some point in their life. The number of allergies is increasing every year, especially amongst young children. Some experts believe the increase in allergies is a result of air pollution and environmental factors, while others think it is because our homes are cleaner than ever before; this means the body is not used to germs, which may trigger an exaggerated reaction when a person comes into contact with them.
Allergies differ to intolerances because the immune system is not involved in the reaction produced by an intolerance; consequently, intolerances will not be identified on an allergy test.
Why does an allergic reaction occur?
An allergic reaction occurs when the body comes into contact with an allergen and the immune system mistakes it for a harmful substance. The body’s defence system kicks in and releases antibodies to destroy the ‘threat’. The location of the reaction usually depends on the point of contact with the allergen; usually, reactions are visible on the skin but they may also occur in the stomach, throat or the inside of the lungs.
What causes an allergy?
Some people are predisposed to allergies (this is known as atopy); this is usually due to genetics or the environment in which they grow up. People that grow up in polluted areas, in smoky households and around dust and pets are more likely to suffer with an allergy.
In other cases, the cause of the allergy is unknown and the reaction is generated by the release of the antibody immunoglobulin; this chemical stimulates the release of other chemicals, including histamine, from other blood cells; this process results in the symptoms of an allergic reaction.
If you display the symptoms of an allergy, you should consult your GP. Your GP will discuss your symptoms with you and try and identify the cause of the reaction; in some cases, the allergen will be very obvious but in many cases, it is more difficult to identify the exact cause of the allergic reactions. In some cases, the GP will recommend you have tests to determine the cause of the allergic reactions; there are many tests available, including:
- Skin prick test: this test is usually carried out first. It involves pricking the skin with a needle that contains a very tiny amount of the suspected allergen that is causing negative reactions; if the skin reacts, the allergen has been successfully identified.
- Blood test: a blood test is used to measure the levels of the antibody immunoglobulin in the blood following contact with a suspected allergen. The results of the reaction are graded from 0 to 6, with 0 constituting no reaction and 6 indicating a severe reaction.
- Patch test: a patch test is usually used to identify the allergen that causes skin conditions such as dermatitis and eczema. During the test, a metal plate containing the suspected allergen is placed on the skin for a period of around 48 hours; this test is usually carried out in hospitals.
Doctors do not recommend using at home testing kits as they are often less accurate than NHS tests; it is also advisable to have your results interpreted by a medical expert, rather than relying on printed guidelines included with a home test.
There are hundreds of different allergens, but a large proportion of the population suffer with a small number of allergies; common allergies include:
- Tree, grass and flower pollen
- Dust mites
- Animal hair
- Bee and wasp stings
- Mould and fungal spores
- Food allergies (including nuts, eggs, soya, wheat and seafood)
- Medications (including penicillin and aspirin)
Symptoms of Allergies
There are many different symptoms which may present in the event of an allergic reaction. Most reactions are mild, but some can be severe and may in extreme cases, be life-threatening (this is known as anaphylaxis). Anaphylaxis affects around 1 in 1,000 people. Some of the most common symptoms are listed below:
- Skin irritations and rashes (these usually appear as red, blotchy patches on the skin)
- Itchy, swollen or red eyes
- Runny nose
- Sinus pain (this is usually felt in the forehead, around the nose and eyes and in the temples)
- Swelling in the lip
- Itchy throat, nose and the roof of the mouth
- Breathing difficulties (this is usually an increased breathing rate, but some people do experience slower breathing rates)
- Swelling in the throat
- Increased heart rate
Treatment for allergies
There are many different types of treatment available for people that suffer from allergies. The type of treatment you are given is usually dependent on the type of allergy you have and the severity of the reaction you produce when you come into contact with the allergen.
- Antihistamine- Most people with mild allergies can be treated effectively with antihistamine medication; this type of medication eases symptoms of allergies such as animal hair, dust and pollen. Antihistamines work by preventing the action of histamine. Antihistamines are widely available and come in the form of nasal sprays, tablets, creams and eye drops.
- Decongestants- these help to ease symptoms which cause the head to feel heavy and blocked up; decongestants can be used to tackle sinus pain, blocked noses and sore throats. They are widely available and usually come in tablet and spray form.
- Leukotriene receptor antagonists- these medications help to prevent the actions of leukotriene, which is a chemical released during an allergic reaction. This medication is commonly used to treat asthma.
- Immunotherapy (also known as hyposensitisation)- this treatment is used to gradually increase the body’s tolerance to an allergen by bringing the body into contact with it and gradually increasing the dose of the allergen. This treatment works by encouraging the body to produce antibodies to prevent the reaction in the future. It is important that this treatment is carried out under strict medical supervision as there are risks involved. This treatment is most commonly used to treat allergies to bee and wasp stings.
Treatment for anaphylaxis
Anaphylaxis can be very dangerous as the allergen triggers very serious and potentially life-threatening symptoms. Treatment for this condition usually involves carrying an adrenalin injection, which is commonly known as an epi-pen. The epi-pen should be used if the patient experiences symptoms such as difficulties with breathing or tightening in the chest and throat; the injection is administered by the patient and can produce quick and effective results; if symptoms persist, you should seek emergency medical help. Doctors recommend that patients with severe allergic reactions should carry two injections with them at all times; if you work with other people or you attend school or college, you should let everybody around you know where you keep your epi-pen so that they can help you in the event of an adverse reaction.