What is allergy?
An allergy is an abnormal reaction or increased sensitivity to certain substances. The allergic individual produces symptoms when exposed to these substances which are harmless to non-allergic people.
The main reason for this is that allergic people make a special type of antibody called Immunoglobulin E (IgE) which can react with environmental substances in a harmful way. These substances are called allergens.
The reaction between allergens and IgE antibodies causes release of substances such as histamine which produce allergic symptoms in the skin, the nose, the eyes, the chest, etc.
The most common allergens are animal danders, pollens, house dust, house dust mites, molds, some drugs and many foodstuffs, especially fish, eggs, milk and nuts. Bee and wasp stings may cause allergic reactions with fatal results in rare cases.
Additionally, feathers, wool, dyes, cosmetics and perfumes may act as allergens.
Allergic reactions or diseases may involve any part of the body, the most frequently involved being the nose and chest with resultant symptoms of hay fever, rhinitis or asthma, respectively. The skin and eyes also commonly show allergic symptoms. Anaphylactic shock is severe allergy which affects many organs at the same time – causing a rapid decrease in blood pressure, fainting and, occasionally, death. Such a reaction, though, is rare.
If you suffer from hay fever, the pollens of grasses, weeds and trees are the main causes of this type of allergy, although mold spores can also cause the symptoms.
The lining of the nose becomes swollen and exudes a runny discharge. Spells of sneezing and itchiness of the throat and palate also occur and the eyes may be similarly affected. Depending on where you live and the pollinating periods, attacks may occur in spring, summer or autumn.
In perennial allergic rhinitis, the symptoms are similar to hay fever but appear all the year round. This condition is caused by non-seasonal allergens such as house dust components and certain molds.
You are more likely to suffer from an allergic condition of the eyes as an adult. Allergic conjunctivitis is often associated with allergic rhinitis. A general complaint is of itchiness of the eyes, which are rubbed frequently.
If you are asthmatic, you can suffer from attacks that obstruct the flow of air to the lungs. Breathing becomes difficult and forced breathing becomes necessary. A wheezing sound appears, due to the rush of air through your narrowed airways. At the same time, a troublesome cough can develop. Asthma may begin at any age and, if neglected, tends to recur and become chronic.
Asthma may be allergic or non-allergic in origin. In allergic asthma, environmental allergens trigger the disease when inhaled or ingested.
If you suffer from eczema, your skin can become irritated and develop rashes that can be either wet or dry and occasionally chapped. The reactions are often accompanied by severe itching. The cause is often not clear, but is frequently seen in children of families with a history of allergic diseases. The eczema usually starts during the first year of life, on the face. Later, it is often seen on the inside of the elbows and backs of knees, on the neck, on the ankles, on the wrists and on the back of the hands. The eczema, in most cases, disappears during the teens.
Nettlerash (Urticaria, Hives)
This reaction appears very suddenly. Your skin becomes warm, reddish and itching. The symptom may last either for a couple of hours or up to a whole day.
With contact eczema, your symptoms will be similar to those of the eczema previously described, but the allergic reaction is of another type. The cause is direct contact with different substances, such as:
- nickel (in coins, stainless steel, clasps)
- rubber products (in gloves, boots)
- chromium (in cement, leather)
- preservatives (in creams, ointments and cosmetics)
This condition, unlike those listed above, is not due to the production of IgE antibodies, but is due to a different kind of immune reaction.
The stomach and the digestive system are also frequent targets for allergic disease. Your symptoms are caused by allergy to foods — which can result in vomiting, stomach pains, diarrhea or constipation. Frequently, eczema and hives may be produced after ingesting food to which you are allergic. Food allergy may also trigger asthmatic attacks and, rarely, generalized anaphylaxis.
Severe allergic reactions to bee and wasp stings are not uncommon. The local toxic reaction and discomfort that usually occurs following an insect sting is not generally considered to be allergic. IgE mediated (allergic) reactions induce symptoms such as nettlerash (urticaria, hives), running nose and eyes, swelling of the throat, attacks of asthma and, in severe cases, fainting.
Should you be highly sensitive to bee or wasp stings, you may become unconscious within a short space of time. Immediate action should be taken to get you expert medical treatment, preferably at the nearest hospital.
The term occupational allergy is generally used to describe episodes of allergic reactions occurring after working with industrial dusts, vapors, gases or fumes. Furthermore, substances like nickel (in coins), chromium (in cement), rubber, different dyes, formaldehyde and glues may result in eczema that occurs at the site of contact with the skin.
The degree of eczema depends on the length of exposure and sensitivity to the substance. Symptoms may show within some weeks — but it can often take months, years, sometimes decades, before an eczema develops. Any part of the skin may become affected, but the most frequent sites are the hands, arms and the face because these tend to be the least protected parts of the body.
Allergy is an unusual reaction or sensitivity to substances that do not bother most people.
IgE Mediated Allergy
Following exposure to common environmental allergens, the allergic individual produces a special type of antibody, called Immunoglobulin E, or IgE. The healthy individual has a very low level of IgE in the blood, while those with certain allergic conditions such as hay fever, allergic asthma, and some forms of eczema, have high IgE levels.
In the human body, certain cells called mast cells and basophils are involved in allergic reactions. IgE, produced as a result of repeated allergenic stimulation, attaches to the surface of these cells and subsequent binding of the allergen triggers a biochemical reaction, leading to the release of different substances. These substances cause a build-up of fluid in the tissue, and contraction of the smooth muscles. Depending on the route of entry of the allergen and where the reaction takes place, different symptoms will occur.
If the reaction takes place in the nose and eyes, hay fever will result — while asthma is the result if the chest is affected. Eczema appears when the skin is affected.
Non IgE Mediated Allergy
Mechanisms other than IgE can trigger an allergic response resulting in symptoms in various organs. Sometimes, especially if asthma starts in adult life, no apparent cause can be found. Usually, the first outbreak of symptoms follows an infection that may have been either bacterial or viral in origin.
The common cold, cold moist weather, smoke, chemicals and psychological or physical stress can be responsible for episodes of this type of asthma. Most occupational allergies, such as contact eczema, are not IgE mediated.
Who Becomes Allergic?
Anyone can develop an allergy, but the probability is increased if one or both parents suffer from some kind of allergic condition. Indeed, the presence of another allergic individual in the family is the strongest factor for predicting allergy in a child. It must be noted, though, that even when both parents are affected, a child may not be. Conversely, allergic children are born to normal parents and in such cases other factors, such as infection, may be responsible for the development of the allergy.
It is essential for successful treatment that the allergens responsible for the symptoms are accurately identified. There are different ways to arrive at a diagnosis. The case history is extremely important in all allergy investigations. Based on what the patient tells about his/her symptoms, the doctor decides what tests should be carried out.
The case history should form the basis for all allergy investigations. In order to give the doctor an idea of the mechanisms and allergens causing the trouble, the doctor will question the patient or ask him/her to fill in a questionnaire.
It is important to know when and how the symptoms developed. Also important is the relationship to seasons, damp weather, physical activity, certain foods, etc. Knowledge of personal habits such as smoking, occupation, hobbies, etc., will be necessary and some information about the home can be important (e.g., whether there are pets, or fitted carpets in the house or if cleaning aggravates symptoms). A favorite cologne or perfume can be the cause of allergic conjunctivitis, whilst a soap may be the cause of chronic eczema.
In nasal allergies, the case history alone may give enough information to settle the diagnosis and the doctor can then decide which measures to take to help the patient. In more complicated cases, however, further investigations have to be performed to get a final diagnosis.
Skin test procedures are used by many doctors to identify allergens responsible for the symptoms. There are several methods of skin testing.
Drops of the suspected allergens are put on the skin of the forearm and the skin is either pricked or scratched (prick or scratch test) through the drops. Suspected allergens can also be injected into the skin of the back (intradermal skin test). After 15-20 minutes, if there is an allergy to one or more of the substances, a round wheal with a flare forms on the spots where the substances were injected. This may identify and confirm the allergy.
However, besides causing the patient some trouble, the intradermal skin tests are not very reliable. Drug treatment for the allergic symptoms in the 24 hours prior to the skin test may invalidate the results, and skin testing in small children is both inconvenient and unreliable.
Patch testing is used in the investigation of allergic contact eczema. The test is performed by using a small piece of blotting paper, moistened with the suspected substance, or a prepared strip containing various standard allergens. The paper or strip is taped to an area of healthy skin for 24 or 48 hours.
If you are allergic to the substance tested, eczema will be seen where the test substance has been in contact with your skin.
Provocation and Elimination Tests
These tests are performed in the eyes and nose in hay fever sufferers, but in the airways in asthmatics. A highly diluted allergen extract is dropped into the nose or eyes or is inhaled. The test is continued in this way, using more concentrated allergens until the allergic symptoms are provoked. This shows that the tested allergen is responsible for the patient’s symptoms.
When allergy to food is suspected, different foods (usually those most commonly associated with allergy) are eliminated to see if the symptoms disappear. They are re-introduced into the diet, one by one, to see if any of them causes a return of the symptoms.
The skin and provocation tests, apart from being inconvenient to the patient, have other disadvantages. The bronchial provocation test is not without risk, and may be influenced by medical treatment and the physical and mental condition of the patient.
IgE plays an important role in allergic rhinitis, allergic asthma and in some forms of eczema. Detecting and accurately measuring the amount of IgE is, therefore, of great importance when diagnosing allergies.
Because of the limitations and disadvantages associated with skin and provocation tests, there has been a need for more convenient and reliable methods. Today, there are laboratory tests available that accurately measure IgE, and a small blood sample is sufficient for allergy testing. These tests measure either the total amount of IgE in the blood, which indicates if your symptoms are of allergic origin; or specific IgE, which tells the doctor which allergens are causing the trouble.
Due to their ease of use, reliability, convenience and accuracy, these tests have become routine and form an important part of the diagnostic work.
It is necessary for successful treatment that the allergens are accurately identified. There are three main objectives in the management of allergic disease:
- to eliminate causative factors from the immediate environment, where possible.
- to reduce irritation in the tissue (i.e., to treat the symptoms with different drugs).
- to decrease immunological reactivity by vaccination (specific hyposensitization).
In this disease, the primary concern should be to avoid the responsible allergens. (See special advice for patients with allergy to animals, dust, molds and pollens).
Drugs frequently used in the treatment of hay fever are the antihistamine preparations. These reduce the swelling of the lining of the nose and conjunctiva of the eyes. However, a common side effect is drowsiness and it is advisable not to drive a car or operate machinery during this treatment. There are also antihistamines in the form of eye drops, which decrease the swelling of the conjunctiva.
In very severe cases of hay fever, injections of long-acting corticosteroids are used during the pollen season. If the allergens cannot be avoided, and drug treatment for some reasons is not indicated, then allergy vaccination (specific hyposensitization) may be of value. In the treatment, the specific allergen or allergens to which you are allergic, are injected. The first injections are very diluted and are carried out at short intervals. The concentration of the allergen is then increased gradually until a maintenance dosage level is reached. Treatment may continue for years and it is used mainly in pollen allergy.
Side effects, such as itching and swelling at the injection site, can occur if the dose of the allergen is too high. Occasionally, more severe reactions may occur — which is the reason why the patient should be kept under observation for at least 15 minutes after each injection. It is important to let the doctor know if any kind of skin reaction appears during the first 24 hours following any injection.
The effect of hyposensitization is to increase resistance to the allergen. Usually, this will mean that the number of allergic attacks will be reduced or that they will disappear completely.
Most patients with conjunctivitis have hay fever symptoms and the guidelines given above apply.
The treatment varies, depending on the kind of disease. If a correct diagnosis is made, where the cause is identified as being some type of allergen, avoidance of the allergen or allergens is the first step.
When the cause of the symptoms cannot be found, or if the disease cannot be controlled by the aforementioned ways, drug treatment may be necessary. Most patients benefit from regular administration of bronchodilators that make it easier to breathe. This type of drug is available as tablets, sprays, injections and suppositories, and contains either adrenaline or theophylline.
The spray can also be used during attacks, with almost immediate effect. When the airways are almost completely closed, either the injection form has to be used or a solution administered with a nebulizer. Side effects could appear as an increase in pulse rate and trembling. It is important that you follow your doctor’s advice and do not use the spray too often. In severe asthma, corticosteroids can be used either in the form of tablets or spray. The risk of side effects of the spray is extremely low in contrast to tablets.
These drugs relieve symptoms in both allergic and non-allergic asthma. Disodium chromoglycate prevents the allergic reaction. This drug is available as a spray and may be taken after a bronchodilator to achieve the best result. Side effects are rare. It must be remembered that the action of this drug is to prevent attacks, not cure them. It is of little value during acute episodes and it is important to maintain your regular dosage, even though you may be feeling well and suffering no symptoms.
The treatment consists of steroid ointments (cortisone) in periods of flareup, and bland ointments in periods when symptoms are at a minimum.
Nettlerash (Urticaria, Hives)
There is no need to use ointments to treat nettlerash (urticaria, hives). The best treatment is to use antihistamines.
If it is possible, it is best to avoid the agent responsible. Avoid contact with irritating substances like organic solvents, polishes, cleaning materials, etc. Drug treatment is similar to that of eczema. Some general advice is as follows:
- avoid contact with allergens to which you seem to be allergic (e.g., dust, pollens, molds and animal danders.
- as anxiety may cause outbreaks of the disease, keep children as contented as possible.
The essence of treatment is to avoid particular foods responsible for symptoms. At all times, though, the adequacy of any diet should be discussed with your doctor to ensure a sufficient intake of essential nutrients.
The allergic patient is treated with injections of bee and wasp venom, administered in increasing doses, to stimulate the body’s protective mechanism against the effects of further stings. Strength of the initial dose is determined by a series of skin tests, since different allergic individuals can show varying levels of sensitivity to the sting. This procedure is generally carried out, initially, by a specialist clinician — but it can be continued by your local general practitioner, once the maintenance level has been reached.
Allergy to Animals
If you are allergic to animal hair or fur, reduce contact with them to a minimum. Symptoms will disappear, at least for a while, following removal of hair and fur from the environment. In many cases, removal of household pets is the only solution — although it can prove to be very traumatic.
Should removal not be possible, do not allow the pet in the bedroom and carefully vacuum daily. If a member of the family is allergic, it is useful as a preventative measure to remove animals from the home even if no allergy to the specific animal has been found. This may help to prevent additional allergies from developing. It follows that any patient allergic to animals should not have furred or feathered house pets, even if
allergy to that specific animal has not been found. Carpets, fabrics, etc., made from animal hair should be avoided if possible.
Contact with animals outside the home should be avoided (e.g., if you are allergic to horses, you should not ride). A problem can arise when allergic individuals visit the homes of pet owners and the best solution is to take a symptom-preventing drug prior to the visit. Remember, also, that symptoms can be provoked at circuses and zoological gardens.
House Dust Allergy
If you are allergic to house dust, your home should be vacuum-cleaned daily, especially the bedroom; this cleaning being done by someone who is not allergic. Fitted carpets and dust-collecting furniture should be avoided. Bedrooms should be kept as dust free as possible. Mattresses and pillows are best made of synthetic material.
Allergy to house dust might be similar to or the same as allergy to house dust mites, which are microscopic creatures living in bedding and carpets. Mites cannot survive in low temperatures; thus, one way to get rid of them is to occasionally place the bedclothes and carpets outside during winter.
Molds live in moist environments. If you are allergic to molds, you should avoid moist rooms such as basements and you should not use humidifiers. House dust may contain large amounts of mold spores.
In some patients, an allergic reaction may be brought on by different foods containing or contaminated with molds (e.g., cheese, dried fruit, mushrooms, soy sauce, wine and beer).
You should avoid areas where molds thrive (e.g., piles of leaves, wood logs, areas of deep shade or heavy vegetation). Your lawn should be kept mown and old leaves collected by someone else.
Traveling in the countryside during the harvest season should be avoided, as should walks in the woods. A summer cabin closed up all winter should be aired and cleaned before a mold-allergic person stays there.
In theory, one way to avoid an allergen is to move to another location where the plant responsible does not grow. This is not always practical, however, since there might be a need to change jobs, school, friends, etc.; and besides, the person with a pollen allergy may very well become allergic to different pollens in his/her new location.
Partial avoidance can be achieved without moving. Many people take their vacations during the pollinating period and choose a place that is free from the specific pollen. Direct contact with the pollen (picking flowers and twigs, having flowers indoors) should be avoided.
It is useful to keep bedroom windows closed to prevent the wind bringing in pollens. It is also advisable to air bed linen in the morning when the pollen count is at its lowest. When there is a lot of pollen in the air (e.g., hot, dry day), it may be necessary to stay indoors with the doors and windows closed.
You can help prevent being stung by avoiding places that might attract bees or wasps. The same can be said for not wearing clothes that might also attract these insects. Other tips are:
- Keep an insecticide spray, specific for wasps, handy in the home, car, or at work.
- Do not use perfumes, hairsprays, scented lotions, etc., out of doors.
- Do not walk barefoot outdoors.
- Do not wear loose clothing. Avoid black or bright colors.
- Avoid exposing limbs. Wear gloves and a head covering when gardening.
- Check areas around your home that might have a wasp’s nest and have them removed, if possible.
- Avoid orchards and other places that attract bees and wasps.
- Do not eat outdoors.
- If bees or wasps hover near you, do not blow or strike at them but, instead, turn or walk away slowly keeping your head down.
- Always carry an emergency treatment kit if your doctor prescribes one.
- Consult your doctor if you have any questions about treatment or prevention of allergies to stinging insects.
- It is advisable to carry an identity card that states you are allergic to bees or wasps in case you are found unconscious after being stung.