How long before amoxicillin works on tooth infections?

Usually couple days: It will typically take more than 24 hours before you gain any relief. If it is a severe infection, you will likely want to have treatment other than oral antibiotics.

Antibiotics: Oral administration of antibiotics usually starts to help the affected area in 24-48 hours. Then the area needs to be treated to remove the source of the infection(extraction or root canal therapy).

Antibiotic kicks in?: Usually a good 24 hours before you can start to feel or see results, the important thing to remember with any antibiotic regimen is to take the entire prescription, so if 3 days later it is working and you have tooth extracted or root canaled, and script was for 7 days or more, continue to take it until completed.