How long does it take for tooth infection swelling to go down?

Depends: The particular type of tooth infection, its cause and the treatment modalities will help to determine the efficacy of treatment. The swelling is a result of inflammation and when the inflammation is reduced there will be a gradual reduction in the swelling. If the treatment is appropriate it is likely that the swelling will be reduced within 5 to 7 days. If not, go back to your dentist.

Antibiotics: If just on antibiotics you could expect 2-3 days, if you have had the tooth worked on and antibiotics it should be noticable sooner. See your dentist if you haven't.