What is an Allergy?
An allergy is an immune response to a substance (allergen) which is normally harmless to the body. These substances cause hypersensitivity and include things like food, fur, pollen, insect bites, latex, medications or dust. (1)
Your immune system mistakes allergens for something invading the body which causes harm. When a person is sensitive to a particular allergen the body reacts by triggering antibodies.
These antibodies travel in the bloodstream to cells, which release histamine and other chemicals, to fight the allergen, causing a reaction. (2)
Most allergic reactions trigger symptoms affecting the skin, nose, throat, lungs, sinuses or digestive system. Some allergens can cause asthma like symptoms. If an allergy is extreme it can cause anaphylaxis, a life threatening condition.
We will detail the symptoms and some of the possible causes for each.
Sneezing, Runny or Stuffy Nose
Everyone sneezes from time to time, however when this is accompanied by a runny or stuffy nose you could have an allergy. You might also feel that your nose and eyes are itchy.
Called allergic rhinitis (hay fever), this common reaction affects up to 20 percent of the population, and is rising.
Mild cases generally don’t cause too many issues and last for about six weeks. However when persistent and long lasting, the symptoms can have a detrimental effect on everyday life.
They can interfere with sleep or impair your ability carry out daily activities, or to play sports or exercise. Severe instances of allergic rhinitis might affect your work or school life and the constant symptoms could cause distress.
Different things will trigger an allergic reaction of this nature. For some people it might be a certain pollen from trees or grass which cause symptoms seasonally. It could also be down to types of molds which only appear during the fall when leaves get wet on the ground.
There are also allergens in our own homes, these include: animal dander (urine, saliva and dead skin cells from pets), cockroach residue, dust mites and household molds. (3)
Wheezing and Shortness of Breath
A whistling or squeak when you breathe accompanied by difficulty breathing, tightness in the chest and coughing can be signs of allergic asthma.
When exposed to a trigger you are sensitive to, your airways become inflamed causing them to swell and become narrower. The production of mucous is also increased.
When severe, this condition can be life threatening.
Common allergic asthma triggers are pollen, extreme weather changes, smoke, chemicals, pet dander and dust mites. (4)
A chronic dry cough which persists for more than a few days can be a symptom of an allergic reaction.
Like the previous symptoms, an allergy cough can be seasonal dependent on the trigger. It is likely you will also have other symptoms like sneezing, runny nose and watering eyes.
Common allergens causing this are again, pollen, smoke, chemicals, pet dander and dust mites. (5)
Changes in the normal appearance of your skin which cause itching or pain might indicate an allergic reaction. Rashes can appear red and raised and might leave the skin blistered, dry, cracked and warm to the touch.
There are three types of allergic skin conditions, eczema, hives and contact dermatitis.
Eczema presents as red, dry cracked skin with raised bumps that might be blistered and ooze. This condition can be triggered by allergies to pets, dust mites, airborne allergens or certain foods. (6)
Contact dermatitis is usually caused by an allergen which comes into direct contact with the skin. Symptoms include itching, blisters, burning and a rash.
There are many things able to trigger this rash which we find in nature and in our homes.
Plants like poison oak and poison ivy, or everyday household products like cosmetics, soaps, creams and hair dyes are some of the culprits. Rubber latex and nickel are also common triggers of contact dermatitis.
There is also the possibility certain products used on the skin will react with sunlight and cause photoallergic dermatitis.
Hives (urticaria) are another form of skin rash caused by an allergic reaction. These itchy, red welts or bumps appear on the body or sometimes move from one area to another.
This condition is thought to affect about 20 percent of the population at some point. Hives can be acute, lasting from a few days to a few weeks, or chronic and last in excess of six weeks. (7)
There are numerous triggers for hives and these include: insect bites and stings, latex, pets, chemicals, plants, cosmetics, foods and medications. Other allergens might be extreme heat or cold, pressure from tight clothing, exercise and sunlight. Some bacterial and viral infections can also result in hives. (8)
Sinus headaches could accompany the other symptoms associated with allergies, particularly those that affect the nasal passages. In fact, a sinus headache might be the only symptom, especially when triggers are pollen, pet dander and mold, (9) .
Food intolerance and allergies have been linked with instances of migraine headaches. Some foods responsible are wheat, tea, coffee, chocolate, beef and sugar cane. (10)
Other allergens contributing to migraine headaches are nettles, wheat, house dust, hazel and olive trees. (11)
Nausea and Vomiting
Food intolerances and ingested allergens arising in allergic reactions can cause vomiting, nausea and diarrhea. (12)
Anaphylaxis is an allergic reaction which is serious and life-threatening. Most commonly linked to foods, insect bites, stings or medications. The body responds in an extreme way, and at speed, to the allergen, sometimes in just a few seconds.
People susceptible to anaphylaxis experience a chemical release by the immune system affecting many parts of the body at once.
As well as the other symptoms we have already mentioned your throat might swell making it difficult to breathe. Other affected parts of the body can also be swollen.
Additional symptoms are stomach cramps and a feeling of impending doom and lightheadedness. Your skin can become red and your heart beats irregularly. You may have an epileptic type seizure.
This condition is a medical emergency which can be life threatening and requires immediate treatment with an injection of epinephrine. (13)
There are no stages linked with this condition it can however be put into three classification categories.
Early Phase Reaction
This describes an allergic reaction within seconds or minutes of exposure, to or ingestion of, an allergen.
Late Phase Reaction
Late phase reaction is typically characterized as an allergic reaction occurring about two to six hours after exposure to an allergen. It will be at its worst between six to nine hours and generally resolves within a couple of days.
Chronic Allergic Inflammation
This category can be determined as the persistent or prolonged reaction to allergens, possibly due to repetitive exposure. (14)
There are different treatments available to deal with an allergy and they include:
There are several medicines which help control the symptoms of an allergy, the most common of which are antihistamines and decongestants.
They work to reduce a runny, stuffy nose and stop sneezing or itching. Corticosteroids can also be effective treating nasal inflammation. (15)
Subcutaneous immunotherapy (SCIT) involves an extract of an allergen being injected under the skin. The frequency and duration of these shots will be decided by your doctor, however treatment can span up to five years.
This treatment changes the immune system and is able to prevent new allergies developing.
Sublingual immunotherapy (SLIT) is a more recently developed therapy which administers allergens by drops or tablets under the tongue. (16)
This is a treatment for severe allergic reactions which is administered by injection. Your medical professional will advise as to how and when you need to use it. (17)
What is an allergy? An allergy is an immune response to a substance (allergen) which is normally harmless to the body. These substances cause hypersensitivity and include things like food, fur, pollen, insect bites, latex, medications or dust.
What are the signs of an allergy? The signs of allergy include a stuffy or runny nose, coughing, wheezing, skin rash and sneezing.
How do you develop an allergy? The immune system is responsible for reacting to allergens and treating them as invaders in the body. Some people develop them and some don’t. (18)
How are you diagnosed for an allergy? A three step approach will usually be used to diagnose an allergy. This starts with a full medical and personal history followed by a physical examination. If the cause of the allergy is not obvious then tests can be done to detect allergens.
What is the best treatment for an allergy? The treatments for an allergy include antihistamines, decongestants and immunotherapy. Your doctor or allergist will decide the best course of treatment for you.
What are the long term complications of an allergy? Persistent allergies can have a detrimental effect on all aspects of daily life for both adults and children.
Is an allergy considered a disability? The “Americans with disabilities act” considers asthma and allergies a disability. (19)
Is there a cure for an allergy? Whilst there is not a cure for allergies, treatments can help manage them and improve quality of life.
Is an allergy life threatening? On occasions, if an allergy is severe (anaphylactic) it can be life threatening.
An allergy is a response by the body’s immune system to something which is normally innocuous, which it perceives as harmful.
The reactions can vary from mild to severe and if extreme can be life threatening.
Fortunately there are treatments which help people manage persistent or severe allergies to enable improvement in their quality of life.