When you're fighting an infection, nearby lymph nodes get bigger and become tender. Normally, lymph nodes are less than 1/2 inch across (about the size of your fingernail). But, with an infection, they can swell to 2 or 3 times their usual size. They will slowly return to normal in 2 to 4 weeks, when the infection is gone. The lymph nodes may also feel hard or firm, and may seem misshapen. The skin near a swollen lymph node may feel warm. . . lymph nodes are clusters of white blood cells ready to attack the bad bacteria.