Another malady which goes hand in hand with allergies is asthma. I was 45 when a doctor finally diagnosed that I have mild ashtma, and it is definitely related to allergies. It took some very careful listening with a stethoscope to pick up a very slight wheeze at the end of a breath. The asthma usually affects me only during allergy season, although I never use the inhaler except as a precaution when I ski in very cold weather. The main effect is to make my aerobic performace very unpredictable, with really different heart rates for the same level of effort, increasing by about 13-15 bpm when I am feeling an attack. If you find yourself unable to breath, and it turns out to be mild asthma, you can just turn down the jets a bit and let the episode pass.

On another note, most of the new allergy medications are not selected for effectiveness, but rather for having long chain chemicals which do not enter your brain as readily to cause drowsiness. The old standbys, especially triprolidine (actifed), are more effective, but will leave you drowsy.