Treatment for an abscess involves either root canal therapy or extraction of the tooth. Drainage of the abscess should be established either through an opening in the tooth or through the soft tissue in the area. Antibiotics to fight the offending organisms should also be prescribed and taken as directed. It is important to seek treatment for the abscess because delay in treatment can occasionally lead to life-threatening consequences. If left untreated, the abscess can spread to the soft tissues to form an abscess or cellulitis there, or it can spread through the jaw to cause osteomyelitis or periostitis.
Cellulitis is one potentially life-threatening situation.
This is because it is an acute inflammatory process that spreads quickly through the soft tissue, rather than being localized. If the lower jaw is involved, there is potential airway obstruction. In another potentially life-threatening situation, bacteria from the abscess can also penetrate the blood stream, causing the bacteria to spread throughout the body or be carried to the brain. I strongly advise your friend see a dentist to have the area evaluated and treated as soon as possible. You should not rely on this information as a substitute for personal medical attention, diagnosis or hands-on treatment.