Lemon is used to treat scurvy, (swollen bleeding gums and opens infected wounds) a condition caused by not having enough vitamin C. Lemon is also used for the common cold and flu, H1N1 (swine) flu, ringing in the ears (tinnitus), Meniere's disease, and kidney stones. It is also used to aid digestion, reduce pain and swelling (inflammation), improve the function of blood vessels, and increase urination to reduce fluid retention.