When allergies strike, they usually cause itchy eyes and a stuffed-up nose. All this extra mucus can drain down into the chest, creating congestion. Chest congestion can set the lungs up for a secondary problem like an infection, so it is good to clear them as soon as possible.
At the first signs of allergy-induced chest congestion, try to remove yourself from the environment causing the problems. Say you are staying with relatives who have cats, which you are allergic to, and after several days of taking medication you are still feeling wheezy. It is time to go to a hotel for the night. Often simply getting away from whatever is causing the reaction will cure the symptoms.
Moving the gunk in your lungs up and out is the next step. The first phase is to break it up; this can be done by humidifying the lungs with steam. Using a humidifier or even sitting in a steamy bathroom can help.
Next, you want to get that mucus out. Taking a stroll or even a run, if you're not feeling too congested, can help the body clear things out. If the weather is cold or very dry, try to keep the walks brief so as not to add more stress to the lungs. Cold air in lungs that already have an issue can cause further damage to them, and overly dry air has the similar effect of further compromising the tissues.
If you are still feeling weighed down in the chest, using an over-the-counter expectorant might help move things along even faster. An expectorant can be purchased at most drugstores in the cold and flu aisle. An expectorant in conjunction with humidifying and getting a little exercise typically alleviates symptoms. If you continue to experience congestion, it might be time to see a physician for help with the current problem and to discuss how to avoid bouts of chest congestion in the future.
Future allergy attacks can typically be prevented with medications purchased over the counter or by prescription from your doctor. However, if allergy symptoms do occur, taking steps to alleviate them immediately often shortens the period of chest congestion or stops it from occurring completely, as it is one of the later symptoms to occur.