It depends. If your jaw lump is due to abnormal cell growth, it might stay the same, grow, or shrink. If it is caused by infection, it might go away on its own as your body fights the infection or it might go away with some over-the-counter anti-inflammatory medication like Advil or Motrin. If the infection has caused a collection of pus (an abscess) to form, it might go away, but typically this requires draining by a medical professional. Any lump that persists or grows over time should be seen by a medical provider.