I have had a cough for 3 weeks. it is still on and off, and the flem is still of a white color. i don't feel too sick really, but cough is annoying me.?

Cough: Causes of chronic cough may include: post nasal drip ( from rhinitis, allergies, sinusitis), gastro-esophageal reflux, asthma, medications ( ace inhibitors: lisinopril, enalapril, ramipril etc...), smoking etc...

Be patient: Three weeks is not that long so i don't think you have to worry and the white colored sputum is reassuring. The tissue is just healing up.Try over-the-counter cough suppressants which are available. Stay well hydrated and give it some more time and that should resolve. If the cough is not resolved after a month you should probably see your dr. Again to be checked.