Amoxicillin is the top choice for treating a tooth infection in adults. The American Dental Association recommends 500 mg taken three times a day for 3 to 7 days as the standard first-line treatment. If amoxicillin isn’t an option, penicillin V potassium at 500 mg four times a day is the next best choice, though amoxicillin is preferred because it works against a wider range of the bacteria involved in dental infections and causes fewer stomach issues.
That said, antibiotics alone don’t cure a tooth infection. They control the bacteria while your dentist addresses the source of the problem, whether that’s draining an abscess, performing a root canal, or extracting the tooth. If the infection is contained to one small area, you may not need antibiotics at all.
First-Line Antibiotics for Tooth Infections
Amoxicillin and penicillin V potassium both belong to the penicillin family and work by breaking down bacterial cell walls, killing the bacteria rather than just slowing their growth. Amoxicillin has the edge because it’s more effective against certain types of anaerobic bacteria (the kind that thrive in the low-oxygen environment inside an infected tooth) and is easier on your digestive system.
Both antibiotics are prescribed for 3 to 7 days, but you don’t necessarily finish the full course. Current ADA guidelines recommend stopping the antibiotic 24 hours after your symptoms resolve. Your dentist should check in with you within 3 days of starting treatment, either by phone or an in-person visit, to see how you’re responding.
For more aggressive infections, particularly those involving the gums and surrounding bone, dentists sometimes combine amoxicillin with metronidazole. The adult regimen is typically 375 to 500 mg of amoxicillin plus 250 mg of metronidazole, both taken every 8 hours for 7 days. Metronidazole is especially effective against anaerobic bacteria and adds coverage that amoxicillin alone may not provide.
Options if You’re Allergic to Penicillin
A penicillin allergy changes the playbook. Depending on the type and severity of your allergy, alternatives include cephalexin, azithromycin, clarithromycin, or doxycycline. Cephalexin is a common substitute because it’s structurally similar enough to penicillin to work against the same bacteria, but most people with penicillin allergies tolerate it fine. If your allergy is severe (anaphylaxis-level), your dentist will likely steer toward azithromycin or doxycycline instead.
Azithromycin courses are shorter, typically 5 days rather than 7. Penicillin, amoxicillin, and cephalexin courses should not exceed 7 days.
Why Clindamycin Has Fallen Out of Favor
Clindamycin used to be the go-to alternative for penicillin-allergic patients, but that’s changed. It carries a significantly higher risk of causing Clostridioides difficile infections, a serious and sometimes dangerous bowel condition. The American Heart Association specifically flagged clindamycin as an antibiotic to avoid in its 2021 guidelines. Infectious disease specialists have echoed this, noting that clindamycin is both less effective and more toxic than the first-line options. If your dentist suggests clindamycin, it’s worth asking whether one of the safer alternatives would work for you.
When You Actually Need Antibiotics
Not every tooth infection requires antibiotics. If the infection is contained to the area right around the tooth, draining the abscess or performing a root canal may be enough on its own. Your dentist makes a small incision to let the pus drain, washes the area with saline, and sometimes places a small rubber drain to keep the site open while swelling goes down.
Antibiotics become necessary when the infection has spread beyond the immediate area, into neighboring teeth, your jaw, or other tissue. They’re also more likely to be prescribed if you have a weakened immune system. The key point is that antibiotics manage the bacterial spread while the dental procedure treats the actual source. Skipping the dental work and relying on antibiotics alone typically leads to the infection returning.
Dosing for Children
Children’s doses are calculated by body weight rather than given as a flat amount. The standard pediatric dose of amoxicillin for a dental infection is 22.5 mg per kilogram of body weight, taken twice a day, with a maximum of 875 mg per dose. If a child can’t take penicillin-family antibiotics and the allergy risk is high, clindamycin at 10 mg per kilogram (up to 600 mg per dose) three times daily is sometimes used despite its drawbacks, since fewer alternatives are available for children. Your child’s dentist or pediatrician will determine the right medication and dose.
Signs the Infection Is Spreading
A tooth infection that moves beyond the tooth can become a medical emergency quickly. Warning signs include swelling of the face, cheeks, or neck, difficulty swallowing or breathing, trouble opening your mouth, fever, severe headache, nausea and vomiting, double vision, and confusion. Any of these symptoms mean the infection may be entering your bloodstream or spreading to critical areas like your airway or brain. This requires emergency care, not a scheduled dental appointment. Head to an emergency room if a dentist isn’t immediately available.