The best over-the-counter therapy for tooth pain is to alternate ibuprofen and acetaminophen every 3 hours. Take ibuprofen (Motrin or Advil), then three hours later, acetaminophen (Tylenol), then three hours later, ibuprofen, and so on. Continue with this regimen until you see your dentist. Don't take both medications at once; it can be toxic. Ibuprofen works by blocking the production of prostaglandins, which are chemicals in the body that cause pain and inflammation. Acetaminophen works by blocking the production of prostaglandins and also has some anti-inflammatory properties itself. By alternating between these two drugs, you get their separate benefits while reducing their potential negative effects. If you only have access to one type of medication, then use that one that's still in its original packaging. Both ibuprofen and acetaminophen can be harmful if taken in excess of what's recommended, so make sure not to go beyond the prescribed dose. If you miss a dose of either drug, simply start again with your next dose instead of waiting for your next appointment as long as it isn't more than 24 hours after your last dose. If you're asked to wait three hours after taking an aspirin before having something to eat, then don't bother eating before then!