The quitters flu; a number of symptoms that combine in such a manner they closely resemble a cold or flu like illness. Most people who quit smoking will experience it. The symptoms can be headaches, flashes of hot and cold, chest congestion, cough, sore throat and nasal congestion.

The moment you quit smoking your body begins to heal and as a result, these physical symptoms will occur. The most notable of these flu like symptoms are those associated with the respiratory system.

The lungs contain small hair like structures called cilia. (They look more like sea anemones.) These cilia, naturally sweep particles out of the wind pipe to be expelled by coughing. Tobacco smoke coats the lungs with tar and disrupts this process by preventing the cilia from working. When you quit smoking, the tar begins to break down and the cilia once again start cleaning. Quitters will likely notice a blackish – brown and often speckled phlegm as a result. Given the amount of rubbish that builds up in a smokers lungs, this can be quiet extreme and often takes time to settle down

.Here's why you cough so much after quitting smoking:

The reason you can end up with a cough after quitting smoking is in fact good news. Yes, It actually means that the airways are beginning the healing process. It can also be accompanied by a sore throat, sneezing fits and in rare cases even developing sores within the mouth and throat.

Smoking believe it or not actually causes you to cough less which is why many very heavy smokers can carry on smoking even when they have a heavy cold or flu without coughing as much as a non smoker would under similar circumstances.

Tobacco smoke damages tiny little hairs in the airways called Cilia. When you quit smoking then these hairs repair and begin the process of cleaning out the lungs of all the toxins and tar that smoking deposits in the lungs and airways when smoking.