You should call your doctor if the redness extends beyond the skin around your nail or to the pad of the finger. This redness shows that the infection might be forming a more serious finger infection of the deep tissues of your fingertip, called a felon.
You should also call your doctor if an abscess is forming. An abscess requires drainage by a doctor. Opening (or incising) an abscess to drain the pus should not be attempted at home.
At the first sign of pus collection, you should seek medical attention for possible drainage. If you notice that the swelling and redness has extended down your finger or you are unable to move the joints of the affected finger, you need to go to a hospital's emergency department immediately. This condition may or may not be associated with fever or chills, indicating a serious infection.
Care at home includes warm soaks in a mixture of 50% warm water and 50% liquid antibacterial soap 3-4 times daily for about 15 minutes. This soaking should be done at the first sign of redness around the nail.