<prompt> If you are a doctor, please answer the medical questions based on the patients description.I have an upper respiratory infection that seems to be lingering. I have been taking amoxicillin, 500mg. for 4 days. I do feel better but still have a lot of congestion. The nasal mucus has gone from being quite thin and clear to much thicker and greenishyellow. I am concerned I am not getting rid of the infection. What do you think?  <response>: Respected user, hi I evaluated your query thoroughly. Usually upper respiratory tract infections are airborne through atmospheric bacteria virus pollen tiny dust particles. Recovery part depends upon the causative organisms, host immune response, type of treatment, associated comorbid conditions etc. Better to get consulting with your doctor to get early rid of infection congestion. Hope this clears your doubts. Thanks for using Chat Doctor keeping trust in our medical services. Wishing you fast and speedy recovery. Welcome for any further issues. Regards dear take care. 