Amoxicillin is the most commonly prescribed antibiotic for a tooth infection. It’s preferred over other options because it works well against the mix of bacteria found in dental infections and causes fewer stomach-related side effects than older alternatives like penicillin V. That said, not every tooth infection actually needs an antibiotic, and the one you’re prescribed depends on your allergy history, the severity of the infection, and whether it has spread beyond the tooth.
Amoxicillin Is the First Choice
The American Dental Association recommends amoxicillin as the first-line antibiotic for tooth infections. It belongs to the penicillin family but has a broader reach, particularly against certain bacteria that thrive in the low-oxygen environment around tooth roots. Penicillin V is the other first-line option, though dentists tend to reach for amoxicillin first because of its edge in effectiveness and tolerability.
A typical course lasts about seven days. Most people start feeling less pain and swelling within 48 to 72 hours of their first dose, though the infection itself takes a full 7 to 10 days to clear completely. Stopping early, even when you feel better, gives surviving bacteria a chance to rebound.
If You’re Allergic to Penicillin
Since amoxicillin is a penicillin-type drug, it’s off the table if you have a penicillin allergy. The alternatives your dentist may consider include azithromycin and cephalexin (a cephalosporin, which some people with mild penicillin allergies can still take safely). Your dentist will choose based on the type of allergic reaction you’ve had in the past. A mild rash years ago is treated differently than a history of throat swelling or anaphylaxis.
Clindamycin was once the go-to alternative for penicillin-allergic patients, but that’s changed. It carries a Black Box warning in the United States because of its strong link to a dangerous gut infection caused by the bacterium Clostridioides difficile. A large meta-analysis found that clindamycin raises the risk of this infection nearly 17 times above baseline, making it the highest-risk antibiotic in that category. Current guidance advises dentists against using clindamycin for initial treatment of dental infections when safer options exist.
When Infections Need a Stronger Approach
Some tooth infections don’t respond to amoxicillin alone. When the infection is stubborn or involves a broader mix of bacteria, dentists sometimes add metronidazole to the regimen. Metronidazole is especially effective against anaerobic bacteria, the type that live deep in abscesses where oxygen is scarce. This combination targets a wider range of organisms than either drug on its own.
If the infection has spread beyond the immediate area around the tooth, producing facial swelling, fever, or difficulty swallowing, you’re dealing with a more serious situation. These signs suggest the infection may be entering deeper tissue spaces in the head and neck, which can become life-threatening. Uncontrolled swelling near the throat, trouble breathing, or a high fever are reasons to go to an emergency room rather than wait for a dental appointment.
Most Tooth Pain Doesn’t Need Antibiotics at All
This is the part that surprises most people. ADA guidelines are clear: antibiotics are not needed for the majority of dental pain and swelling in otherwise healthy adults. The pain you feel from an inflamed or dying nerve inside a tooth, even when it’s severe, is often best treated by a dentist physically addressing the problem through a root canal or extraction rather than with a course of antibiotics.
Antibiotics are recommended when there’s an actual abscess (a pocket of pus) with signs of spreading infection, or when dental treatment isn’t immediately available and the infection could worsen in the meantime. In that second scenario, some dentists will write a “delayed prescription,” meaning you fill it only if your symptoms get worse or don’t improve within a set timeframe. Over-the-counter pain relief with ibuprofen and acetaminophen, taken together, is often more effective for dental pain than an antibiotic that isn’t needed.
This matters because unnecessary antibiotic use drives resistance. Research on bacteria from dental infections shows that resistance to penicillin-type antibiotics in common oral bacteria sits around 2 to 3 percent in dental practice settings, which is still relatively low. Clindamycin and related antibiotics already face resistance rates above 17 percent in some of the same bacteria. Every unnecessary prescription pushes those numbers higher.
Antibiotics for Children With Tooth Infections
Children get the same types of antibiotics as adults, but the doses are calculated by body weight. Amoxicillin remains the first choice, typically dosed at 20 to 45 mg per kilogram of body weight per day, split into multiple doses. Your child’s dentist or pediatrician will calculate the exact amount. For children with penicillin allergies, azithromycin and cephalexin are common alternatives, also weight-based. Children under 8 are generally not given doxycycline because it can affect developing teeth.
What to Expect During Treatment
The first two to three days are usually the hardest. Pain and swelling start to improve around the 48- to 72-hour mark for most people, but the full course of antibiotics needs to be completed. If you don’t notice any improvement after three days, contact your dentist. The infection may involve resistant bacteria, or it may need to be physically drained.
Antibiotics treat the infection, but they don’t fix the underlying dental problem. A cracked tooth, deep cavity, or failed filling that allowed bacteria in will need a procedure like a root canal, extraction, or drainage of an abscess. Without that definitive treatment, the infection is likely to come back once the antibiotics are finished. Think of the antibiotic as buying time and controlling the spread while you get the actual problem resolved.