Why Do Allergies Make You Cough?

There are literally millions of “bugs” that can make us ill, but generally speaking, we remain healthy most of the time and for that we have to thank our immune system. Fortunately, or unfortunately, depending how you look at it, the immune system has evolved to be able to catch all intruders that come in contact with our body. It’s a case of shoot first, ask questions later… However, this means that in some people, their immune system goes overboard and starts fighting an invasion that hasn’t really happened and that’s when allergies occur. The immune system reacts to harmless substances present around us, making our daily activities uncomfortable or even unbearable.

How does your allergy make you cough?

In addition to sneezing, watery eyes and nasal congestion, one of the most common symptoms caused by allergies is coughing, which can be a nuisance if it becomes chronic. Coughing is a natural way to prevent infection from entering the body and is a very useful defence mechanism. However, in allergic reactions, when you come into contact with a foreign body that is mistaken by an invader (known as an allergen), your immune system overreacts to the substance, and starts producing IgG antibodies. These antibodies bind to mast cells (cells containing granules with histamine), which then trigger a chain reaction, leading to the release of histamine in soft tissues, such as mucus membranes in the nose, sinus and throat. Histamine causes an over-production of mucus, which will eventually start accumulating in your sinuses, once the normal flow down to the nose is blocked due to the inflammation. The accumulated mucus then starts leaking to the back of your throat, causing an irritation and tickling, sending signals to your brain to start coughing. Further problems can occur if you become dehydrated, then the mucus becomes sticky, and bacteria easily gets trapped in the sinus cavities resulting in a sinus infection.

Your immune system is quite stubborn, and if you suffer from a particular allergy, every time you come into contact with the offending substance, you always get the same reaction. In other words, there really isn’t a treatment to cure it, just ways to alleviate the symptoms. This is why prevention is the best way forward and you should avoid exposure to the substance that triggers your allergy. If there’s nothing you can do to avoid the allergen, treatments to mild symptoms generally include antihistamine, to prevent histamine production; cough suppressant, to block cough signal to the brain; and a nasal decongestant, to open the air passage ways and help breathing. In extreme reactions, your doctor may suggest immunotherapy. This is a long term treatment, in which increasing doses of the allergen are being injected into your body.

What are the most likely offenders?

If you have a cough that just doesn’t seem to go away, it may not be a cold, but an allergy. Most common allergies that can cause such chronic cough include polen, dust, pet dander, mold, certain foods and medication. In air-bourne allergens (polen, mold, pet dander and dust), usually the initial symptom immediately on contact with the allergen is sneezing, to expel the invader. When it comes to food allergies, symptoms may develop a few minutes after consumption with nasal congestion or stomach problems. Food allergies are a reaction to specific proteins present in certain foods, seen as a foreign substance that needs to be destroyed. Nearly 90 percent of food allergies are caused only by eight different foods – soy, wheat, milk, tree nuts, eggs, fish, peanuts and shellfish. Finally, certain medications can elicit a similar allergic reaction, including vitamin B12 supplements used to treat anaemia. In all cases, independently of the allergen, prolonged exposure triggers the immune system to respond, inevitably leading to spouts of coughing.

Your immune system is great at remembering previous encounters with intruders, ready for an immediate response in the future. For example, this is why you only get mumps once. However, that same excellent memory means that if it has recognised a particular substance as a potential hazard in the past, it will again every time it comes into contact with it, and there is no way to make your immune system “forget”. Unfortunately for you, if you suffer from any allergies, whenever you’re in the presence of the allergen responsible for your allergy, the same cascade of events occurs, like clockwork, resulting in a variety of symptoms, with couching the most popular. It’s like reading the same book over and over, when you already know how it ends!


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