Amoxicillin is the most widely recommended antibiotic for a tooth infection in adults and children. It’s effective against the bacteria most commonly found in dental abscesses, it’s well-tolerated, and it’s inexpensive. But antibiotics alone don’t cure tooth infections. They control the spread of bacteria while your dentist addresses the source of the problem, whether that’s a root canal, drainage, or extraction.
First-Line Treatment: Amoxicillin
The American Dental Association’s clinical practice guideline places amoxicillin as the go-to antibiotic for dental pain and swelling caused by infected tooth pulp or abscesses. The standard adult dose is 500 mg taken every 8 hours, or 500 to 875 mg every 12 hours. A typical course lasts 3 to 7 days, depending on severity. Finishing the full course matters: stopping early because you feel better can leave surviving bacteria behind and increase the chance of the infection returning.
Amoxicillin belongs to the penicillin family. It works by disrupting the cell walls of bacteria, which kills them. Most oral bacteria responsible for tooth infections remain susceptible to it, though resistance is slowly increasing. Some strains of common mouth bacteria now produce enzymes that break down penicillin-type drugs, which is one reason your dentist may choose a different antibiotic or add a second one for more stubborn infections.
If You’re Allergic to Penicillin
Penicillin allergies are common, and the alternative your dentist picks depends on how severe your allergy is. If you’ve had a mild reaction (a rash, for example, but not throat swelling or difficulty breathing), cephalexin is the typical substitute. The usual dose is 500 mg four times a day for 3 to 7 days. Cephalexin is chemically related to penicillin but is generally safe for people whose reactions were not life-threatening.
If you’ve ever had a serious allergic reaction to penicillin, such as hives, facial swelling, or anaphylaxis, the ADA recommends either azithromycin or clindamycin. Azithromycin starts with a 500 mg loading dose on the first day, then drops to 250 mg daily for four more days. Clindamycin is dosed at 300 mg four times daily for 3 to 7 days.
Clindamycin deserves a specific note on safety. A Minnesota study tracking community cases of a dangerous gut infection called C. difficile found that 15% of patients had received their antibiotic from a dentist, and those dental patients were prescribed clindamycin at five times the rate of other patients. C. difficile causes severe, sometimes life-threatening diarrhea by taking over the gut after antibiotics wipe out protective bacteria. This doesn’t mean clindamycin should never be used, but it’s a reason dentists increasingly favor azithromycin when penicillin is off the table.
When a Second Antibiotic Gets Added
For more severe or spreading infections, dentists sometimes pair amoxicillin with metronidazole. Metronidazole targets a different group of bacteria, specifically the oxygen-hating (anaerobic) species that thrive deep in abscesses and gum pockets. The combination is more effective than either drug alone at reducing deep infection and is commonly used for aggressive gum disease as well as complicated abscesses.
Your dentist may also switch to amoxicillin-clavulanate, a combination pill that includes a compound blocking the enzymes some bacteria use to resist amoxicillin. This is useful when an infection isn’t responding to plain amoxicillin.
Antibiotics Don’t Replace Dental Treatment
This is the single most important thing to understand: antibiotics control the infection, but they can’t eliminate it permanently. A tooth infection starts when bacteria invade the inner pulp of a tooth or the tissue around the root. That dead or dying tissue acts as a reservoir that antibiotics can’t fully penetrate. Without a dental procedure to remove the source, the infection will almost always return once the antibiotic course ends.
A Cochrane review examining adults with abscesses and infected tooth pulp found that adding antibiotics to standard dental procedures (like root canal treatment or drainage) produced no meaningful difference in pain or swelling at 24, 48, or 72 hours compared to the dental procedure alone with a placebo. The dental work itself does the heavy lifting. Antibiotics are most valuable when infection has spread beyond the tooth into surrounding tissue, or when you’re waiting for a dental appointment and need to keep things from getting worse.
Dosing for Children
Children’s doses are calculated by body weight rather than given as a flat number. Amoxicillin for kids is typically 20 to 45 mg per kilogram of body weight per day, split into doses every 8 or 12 hours, with a maximum single dose of 500 mg. For a child weighing 20 kg (about 44 pounds), that works out to roughly 150 to 300 mg per dose depending on severity.
The alternative options mirror adults. Cephalexin runs 25 to 50 mg/kg/day for mild to moderate infections. Azithromycin is dosed at 10 to 12 mg/kg on the first day (up to 500 mg), then 5 to 6 mg/kg for the remaining days. Clindamycin for children is 20 to 30 mg/kg/day divided into three doses. Your child’s dentist or pediatrician will calculate the exact amount based on weight and infection severity.
Signs a Tooth Infection Is Becoming Dangerous
Most tooth infections stay localized and respond well to treatment, but a small percentage spread to the deep tissue spaces of the jaw, throat, and neck. Knowing the warning signs can be genuinely lifesaving.
Swelling that crosses the midline of your face or neck suggests the infection is tracking along tissue planes rather than staying contained. Difficulty swallowing, especially an inability to swallow liquids or drooling because you can’t manage your saliva, is a red flag. A “hot potato” voice (sounding like you’re talking with a mouthful) and a tongue that feels pushed upward or backward can signal Ludwig’s angina, a rapidly spreading infection of the floor of the mouth that can block your airway.
Fever, rapid heart rate, fast breathing, or difficulty opening your mouth more than a finger’s width are all signs of systemic involvement or deep-space infection. Any of these warrants an emergency room visit, not just an urgent dental appointment. At that stage, treatment typically requires IV antibiotics and surgical drainage rather than oral medication alone.
Protecting Your Gut During Treatment
All antibiotics disrupt the normal balance of bacteria in your digestive system to some degree. In the Minnesota C. difficile study, 57% of community-acquired cases had taken an antibiotic beforehand. The risk isn’t limited to clindamycin; any antibiotic course can set the stage for gut problems ranging from mild diarrhea to serious infection.
Eating probiotic-rich foods like yogurt or fermented vegetables during and after your course can help replenish beneficial gut bacteria. If you develop watery diarrhea that persists for more than two or three days after starting antibiotics, or if you notice blood in your stool, contact your doctor. These can be early signs of C. difficile overgrowth, which needs its own targeted treatment.