How long does it take for antibiotic clindamycin to kick in on a major tooth infection?

24-48 hours: Typically most antibiotics can take between 24 and 48 hours to reach therapeutic strength in the body. It can also be dependent on how extensive or extreme the infection is.

Usually 2 Days: A regular tooth infection normally shows signs of significant improvement within 48 hours. However, you said "major, " so it might take a bit longer. If you don't notice a huge improvement within 2 days, it's always a good idea to see your dentist again and perhaps add another antibiotic prescription to what you're currently taking. Don't wait too long & allow the infection to spread or get worse.

Differs: Generally after 24 hours of treatment you should begin to affect the infection. However all people respond differently, and it depends upon the severity and location and duration of the infection. Good luck.