Do you have an allergy?
Wednesday 5th August 2020
Dr John Rees
The UK has one of the highest rates of allergies in the entire world. Allergies can range in severity from mild hay fever symptoms for a few days during the summer to life threatening allergic reactions. There have been many reasons proposed for why we have such a high rate of allergies in the UK with around 40% reporting allergy related symptoms.
Allergies are often the triggers for asthma, eczema and symptoms of hay fever as well as life threatening anaphylactic reactions to foods and drugs. Whether we get allergies depends mostly on our genes. If both your parents have an allergy then the risk of you having allergies too can be as high as 80%. These genetic risks together with becoming exposed, sensitised and environmental factors combine to determine whether we get symptoms on further exposure to the same allergens.
Diagnosis of allergies
The cornerstone of an allergy diagnosis is a good clinical history taken by your doctor. This can be supplemented with common allergy tests to provide further information. Knowing that your symptoms may be triggered by an allergy can help you take steps to avoid the specific allergens and help improve your symptoms.
- Total IgE - a measure of the level of allergy antibodies in your blood known as immunoglobulin E (IgE). A very low level of total IgE means that you are very unlikely to have allergies whereas people with multiple or severe allergies often have very high levels of total IgE antibodies in their blood. A total IgE test, together with a clinical history can help your GP determine whether any further testing would be of value
- Specific IgE blood - these detect IgE antibodies in your blood that react specifically with individual allergens such as a particular species of dust mite, type of pollen or food. These types of tests were developed in the 1960s shortly after the discovery of immunoglobulin E and originally called RAST tests. The RAST test used to use radioactive Iodine as a detector for the allergy antibodies and take days to produce a result. These days, many laboratory and point of care tests take less than an hour
- Skin prick testing - shows whether you have a clinical reaction to specific allergens. This involves having a drop of allergen placed on your skin which is pricked through with a sterile needle. A wheal and flare response indicates sensitivity to the specific allergen. The results of skin prick testing can vary between different clinicians and the source of the extracts manufactured by the different pharmaceutical companies
- Patch testing - used to identify the triggers of contact dermatitis, for example, nickel causing 'jeans button' allergy
Types of allergies
There are many different types of allergic reactions;
- True allergies
These allergies are responsible for symptoms such as hayfever, asthma, eczema, food allergies and anaphylactic reactions and are often triggered by everyday things such as dust mites, pets, pollens and foods. These types of allergies can be diagnosed from a good clinical history and blood tests or skin tests that measure the levels of antibodies known as Immunoglobulin E (IgE). People with many sensitivities or severe symptoms often have very high levels of IgE in their blood.
- Food intolerances
Food intolerances are difficult to diagnose as the symptoms can be highly variable triggering anything from tiredness to IBS type symptoms. One of the most serious forms of food intolerance is coeliac disease (also spelt celiac) which is an intolerance to gluten found in wheat, barley and rye. Only 1 in 5 people with coeliac disease has been diagnosed putting others at risk of severe complications later on in life such as osteoporosis, infertility and bowel cancer. Thankfully, there are now excellent blood tests for coeliac disease and also reliable self test kits such as the SELFCheck Gluten Sensitivity Test which will give you a result in just 15 minutes. Another major food intolerance is lactose intolerance which is caused by your body producing insufficient digestive enzyme called lactase which is responsible for the digestion of lactose the sugar found in milk. Many people with undiagnosed coeliac disease may also suffer from lactose intolerance. Other food intolerances are difficult to diagnose by the conventional methods that your doctor would be familiar with.
- Contact allergies
These reactions often cause skin rashes and dermatitis. The triggers can range from occupational allergens through to foods and inhalant allergens. A frequent cause of contact dermatitis is sensitivity to nickel.
Common causes of allergies
Dust mites are one of the most common triggers of allergy symptoms - much more so than food allergies and intolerances. House dust is a complex mixture of fibres, minerals, dried food, moulds and microscopic spider like creatures called house dust mites. Dust mites live in nearly all homes and feed on flakes of human skin. They normally live unnoticed in warm and moist places such as bedding, sofas, curtains, carpets and children's furry toys - but if you have an allergy to them you may well notice the symptoms!
Many people with asthma, eczema and rhinitis (hayfever) have symptoms all year round and are sensitive to the waste products of the house dust mites.
The common symptoms of asthma, eczema and rhinitis (hayfever) are often associated with dust mite sensitivity and may include itchy, runny or blocked nose and sneezing, itchy red, sore eyes, itchy sore throat and tongue rashes and eczema.
It is almost impossible to completely eliminate dust mites in your home. As a general guide if the amount of moisture (humidity) in the air in your home is high then so will be the level of house dust mites;
- reduce indoor humidity with a dehumidifier
- use a high filtration vacuum cleaner
- vacuum your mattress, carpets and soft furnishings at least once a week to remove mites
- wash sheets, blankets, duvet covers and pillowcase regularly (A minimum 60C is required to >ensure dust mites and eggs are killed)
- damp dust all surface to stop the allergens becoming airborne
- keep your bedrooms well ventilated to prevent the build up of humidity
- air your mattress once per month if possible
- protective bedding can be purchased
- use an allercide spray on soft furnishings and carpets to destroy the allergens
Up to 10% of the population may be allergic to pet animals to some degree - for those with asthma this rises to almost 30%. Up to 40% of children with asthma are allergic to cats.
- cats are the most common cause of pet allergy
- dogs are the second most common cause
The cat allergens are present in the skin scales, saliva, sweat glands and tears of the cat but it is distributed over the fur during grooming. The saliva dries on the cat hair and becomes airborne. In dogs the allergen is found mainly in the skin scales and the saliva. Small animals such as mice, rats and guinea pigs also have allergens in their urine and is also found in dust from their litter.
Pets can trigger asthma leading to cough, wheezing, tightness in the chest and shortness of breath. Pets can also be the cause of rashes and eczema. Other allergy symptoms may include:
- itchy, runny or blocked nose and sneezing
- itchy red, sore eyes
- itchy sore throat and tongue
Treatment and avoidance measures;
- don't keep furry pets - however, if you can't bare parting with your pet then try to limit them to one room in the house
- keep your pet out of the bedroom and off any furniture in a room where you spend most of your time, as exposure can be very high
- don't let your pet near your face or clothing as this can exacerbate your symptoms
- wash your pet regularly - allergens can be easily washed away with a wet sponge (wear gloves when washing your pets or better still get someone else to do it or you)
- ask someone else to brush your pet to remove allergens from the fur or hair- preferably outside the house!
- vacuum carpets and soft furnishings regularly to remove animal hairs
- replace bedding that pets have been in contact with regularly - it can take months or even years to remove allergens from fabrics
- consider installing an air cleaner
- If you are visiting the home of a pet owner then request that they do not vacuum clean immediately before your visit as the pet allergens can remain airborne for up to a day making the allergens more likely to be breathed in. There is also evidence that allergen levels can be 200% higher in homes with poor ventilation
- Use an allercide spray on soft furnishings and carpets to destroy the allergens
Pollen Allergy and Hay fever
Hayfever (grass pollen) is one of the most common allergic reactions and complaints in the UK. In general it starts between the ages of 8 and 20 years old, with the symptoms becoming less severe as the person gets older, but unfortunately there is no age limit on who can suffer.
There is evidence that suggests hayfever is increasing in prevalence along with other allergies. It is thought that pollution may be an important contributor.
Acting early in the season can mean you suffer fewer symptoms and suffer less misery. Avoid areas of long grass during the summer months, keep windows closed midmorning, late afternoon and early evening when the pollen counts are highest, keep car windows closed when driving - check whether your car has a pollen filter and whether it needs replacing, wear glasses to reduce contact of pollen with the eyes, check pollen counts broadcast on the TV, radio or listed in newspapers before going out for the day and take avoidance action. Your pharmacist can advise on suitable medications which are available without prescription such as antihistamines, decongestants and anti-inflammatory nasal sprays and eye drops.
Pollen is released from different plants at different times of the year. Knowing when your symptoms occur can help you identify the likely trigger. Hayfever (grass pollen) is the most common seasonal sensitivity.
- Tree pollens - Spring
- Grass pollens (Hay fever) - Summer
- Weed pollens - Autumn
Hayfever symptoms can be experienced all year and may be confused with a cold. They can also trigger more severe conditions such as asthma, cough, wheezing and shortness of breath. Other allergy symptoms may include;
- frequent bouts of sneezing
- runny, itchy or blocked nose
- watery, itchy red or sore eyes
- itchy sore throat and tongue
- headache and loss of concentration
Pollen may be from trees, grasses and weeds with increase in symptoms coinciding with the flowering of these plants. Trees can cause symptoms during Spring, grasses in the Summer, with weeds and mould spores prevalent during autumn and winter. Dust mites can also trigger hayfever type symptoms and if you have a problem all year round these could be the culprits.
Pollen and mould spores are airborne allergens that are blown into contact with the eyes, nose and lungs where they cause symptoms in sensitive people. Plants that cause hayfever are usually those producing vast quantities of pollen and use the wind for pollination. Generally, insect pollinated plants do not contribute to hayfever.
Food allergies are suffered by around a million people in the UK. However, most affected are children under two years old. Food allergy symptoms may include; itching, swelling lips and face, coughing, shortness of breath and wheezing, asthma, dry, itchy throat and tongue, itchy skin, rashes and eczema, diarrhoea, vomiting, headache or anaphylaxis. The most common foods that trigger allergic reactions are; milk, eggs, wheat / gluten, citrus fruits, peanuts, walnuts, fish, shell fish and sesame seeds.
It is important that once you confirm you have a food allergy that you seek medical advice. You should not attempt to check your sensitivity by eating a food you suspect may be causing the problem. Similarly, avoidance of common foods such as milk, eggs or wheat should only take place after consultation with a dietician or your doctor as unnecessary avoidance of these foods can lead to nutritional deficiencies.
Allergic reactions have more than one phase - an early phase reaction which appears within minutes after inhalation or ingestion of an allergen and a late phase which can occur many hours or even a day later. These late phase symptoms may be more severe than the initial early phase reaction and can be confused with a food intolerance. Food intolerance can be caused by a wide range of triggers including true food allergies mediated by IgE antibodies. There are other types of food intolerance, some of which are psychological such as an aversion of a particular foods texture or flavour. People with a wheat intolerance may in fact have coeliac disease - this is usually diagnosed in the first place by a blood test for tissue transglutaminase IgA antibodies (tTG IgA) and if positive, confirmed with a biopsy of the small intestine for examination under a microscope in the hospital laboratory. Some people with intolerance's to dairy products may have a lactose intolerance. Lactose is a sugar found in milk. People with a specific deficiency of the enzyme lactase may have symptoms associated with lactose intolerance after they drink milk.
The SELFCheck Allergy Test
The SELFCheck Allergy Test is a simple blood spot home test that will tell you in 10 minutes whether the level of your allergy antibodies, immunoglobulin E (IgE), in your blood is high or in the normal range. A high level of total IgE (>150kU/L) means that it is likely that you have sensitisation to one or more specific allergens that can be determined by further tests from your doctor. If you have a negative result but still suffer from allergy symptoms please speak with your doctor or pharmacist as some people can be very sensitive whilst having a normal IgE level.
Read more about the SELFCheck Allergy Test
Dr John Rees has a PhD in allergy from the University of London and is a member of the British Society for Allergy & Clinical Immunology and the British Society for Immunology.