Sometimes the body reacts violently to normally harmless substance present in our natural surroundings and lead to a number of symptoms like asthma, irritation of skin, eyes and throat, wheezing, sneezing and coughing. These conditions are collectively called allergy and the substance causing the allergic response is the allergen. The allergen can cause the symptoms of allergy when breathed in, eaten or touched. It is estimated that more than 40 percent of the people around the world suffer from one or the other form of allergy, and each year the prevalence of allergy is increasing. Some allergies may be mild and others severe and some allergic reactions can even lead to paralysis or death if not treated properly and at time.
Types of allergy
There are many types of allergies which are commonly seen. The allergic responses are broadly classified to five major groups according to the body part on which they produce the symptoms and on the type of allergen causing the symptoms.
Respiratory allergies are caused by the over reaction of the immune system to the airborne allergens like pollen, pet hair, tobacco smoke, cloth fiber, dust mites. These allergens usually trigger inflammation, irritation or swelling in the nose, lungs, ears, eyes, sinuses, throat, lungs and larynx. It can also lead to asthma and difficulty in breathing and in some severe cases, death.
The number of people suffering from respiratory allergy is increasing each year and this may be probably due to the rise in the pollutant level in the atmosphere. The symptoms of respiratory allergy includes sneezing, runny and blocked nose, watery eyes, congested ears, head ache sinus pressure and cough. The person suffering from the respiratory allergies may either have one or more of these symptoms which persists for more than a day.
Contact allergy or contact dermatitis is a localized irritation or rashes which are produced due to contact with some foreign substance. Certain metals, jewelry, soaps, detergent, plants like poison ivy or synthetic cloth materials can lead to these allergic reactions on the skin. The most common symptoms of this skin allergy are reddening of the skin, itching, burning and blisters on the affected area of the body. The allergic reaction can be usually seen at the site of contact and in some cases at other parts of the body.
The different forms of skin allergies may include atopic dermatitis, eczema, utricaria and hives.
Atopic dermatitis is a skin allergic syndrome with redness, scaling and itching of the skin often shown together with other allergies like asthma or hay fever.
Eczema is a non infectious skin disorder often associated with skin lesions and hardening of skin.
Utricaria and hives are skin allergies characterized by slightly elevated patches on skin which are itchy and red.
Insect sting allergy
The insect like bees, wasps, ants and bumble bees inject small amount of venom into their prey. Normally insect sting leaves us with a localized irritation and redness which are gone after a short time. Some people are allergic to insect sting and may produce certain elevated responses like hypotension, dizziness, vomiting, asthma or even anaphylactic shock and death. Each year more than thousand people lose their lives because of the allergic reactions caused due to insect sting.
People are allergic to all sorts of foods from eggs and shell fish to apples and rice. The most common food allergies observed are allergy to egg, cow's milk, shell fish, nuts (mainly peanut), soy protein, and wheat. Allergies to rice, apple, pears, and corn are also seen even if in low numbers. Mostly, the people are not allergic to the whole food itself but some protein or macromolecule in the food may act as the allergen. The symptoms of food allergy may be shown within minutes of having the food or it may be shown after a few hours. The allergy may manifest itself as nausea, irritation of the throat, skin rashes and blisters, eczema, hypotension or anaphylaxis.
Sometimes the body may produce allergic reaction against the medicine or drug prescribed for us. The allergy to medicine is entirely different from their side effects and the allergic symptoms are produced after a few days of having the medicine. Most people are allergic to the antibiotic penicillin and related medicines, and even aspirin and general or local anesthetics are also known to produce allergy in a few. The most common symptoms of drug or medicine allergy is skin rashes and utricaria.
Allergy can also be grouped into indoor or outdoor allergy depending on the source of allergy.
Indoor and outdoor allergy
Based on where the allergens are usually found in nature the allergy can be classified as indoor or outdoor allergies. Dust mites, pet hairs, cockroaches, mold spores all of which are found inside the house in spite of all the precautions, are the main cause of indoor allergy. The high levels of indoor allergens are the main cause of asthma and breathing difficulty in most cases. Allergic retinitis is also due to indoor allergen like dust mites and mildews. Pollen and air pollution are the main cause of outdoor allergy. The concentration of pollen and the different atmospheric pollutant are high in the outdoor areas than at home.
Pollen allergy is most common allergen during the spring season and it causes the condition called hay fever which is marked by sneezing, coughing, stuffy nose, watery eyes, breathing problem, asthma and skin rashes. Pollen from different species of grasses, plants and trees can cause the allergic symptoms but not all pollen causes allergy to everyone. As the pollen are produced during the spring or the flowering season and the related allergy is seen at this particular season, pollen allergy may be included under seasonal allergy which is different from the year round allergies like contact allergy and food allergy.
Spring is not only the time you get a seasonal allergy, if you are allergic to grass pollen the time for your seasonal allergy is summer and winter is the best season to get allergy from the indoor allergens like dust mites and mold spores.
Whatever be the allergy, it is always better to stay away from the allergen and avoid the attack. But there are cases when you can't completely avoid the allergen, in such situations it is better to keep the medication at hand and get the medical advice at the earliest to avoid further complications.