Amoxicillin is the first-line antibiotic recommended by the American Dental Association for tooth infections, typically prescribed at 500 mg three times per day for 3 to 7 days. But here’s the important thing to understand: antibiotics don’t actually relieve tooth pain on their own. They fight the bacterial infection that may be causing the pain, and it usually takes 48 to 72 hours before you notice improvement.
When a Toothache Actually Needs Antibiotics
Not every toothache is an infection. A cracked tooth, an inflamed nerve, or gum irritation can all cause significant pain without any bacteria being involved. Antibiotics won’t help in those situations, and taking them unnecessarily contributes to antibiotic resistance.
Antibiotics are appropriate when a tooth infection has spread beyond the tooth itself. Signs that point to a bacterial infection include fever, swelling in your face or jaw, swollen lymph nodes, or a visible abscess (a pus-filled bump on your gums). If you have tooth pain without these systemic symptoms, over-the-counter pain relievers like ibuprofen are generally more effective at managing the pain than antibiotics would be. The real fix for most toothaches is dental treatment, whether that’s a filling, root canal, or extraction, not a course of antibiotics.
First-Line Antibiotics for Tooth Infections
When antibiotics are warranted, the ADA recommends two primary options:
- Amoxicillin: 500 mg, three times per day, for 3 to 7 days
- Penicillin V: 500 mg, four times per day, for 3 to 7 days
Both target the mix of bacteria commonly found in dental infections, which include streptococcus species and various anaerobic bacteria that thrive in the low-oxygen environment inside your teeth and gums. Amoxicillin is prescribed more often simply because the three-times-daily dosing is easier to stick with than four times daily.
Your dentist will typically want to reassess you within three days of starting the antibiotic. If your symptoms (fever, swelling) have fully resolved, you can stop the antibiotic 24 hours after that resolution, even if you haven’t finished the full course. This is a shift from the old “always finish your antibiotics” advice and reflects current ADA guidelines aimed at reducing unnecessary antibiotic use.
Options If You’re Allergic to Penicillin
If you’ve ever had a serious reaction to penicillin, ampicillin, or amoxicillin (hives, facial swelling, or difficulty breathing), those first-line options are off the table. The ADA recommends three alternatives:
- Cephalexin: 500 mg, four times per day, for 3 to 7 days
- Azithromycin: 500 mg on the first day, then 250 mg daily for four more days
- Clindamycin: 300 mg, four times per day, for 3 to 7 days
Azithromycin has the simplest dosing schedule, which makes it convenient, but your dentist will choose based on the severity of your infection and your medical history. The same 3-day reassessment and early-stop rules apply to these alternatives as well.
Metronidazole for Severe Infections
For more serious infections where anaerobic bacteria are a major concern, dentists sometimes add metronidazole (500 mg every 8 hours) alongside amoxicillin or penicillin. This combination broadens the coverage against the oxygen-avoiding bacteria that are especially common in deep abscesses. Metronidazole is not typically used alone for dental infections. It’s an add-on when a standard antibiotic isn’t enough on its own.
How Quickly Antibiotics Work
Don’t expect immediate relief. Most people start noticing reduced pain and swelling about 48 to 72 hours after their first dose. The infection itself typically takes about a week to clear completely. If you’re not feeling any better after three days, contact your dentist. The infection may need a different antibiotic, or the tooth may need a procedure like drainage or extraction to resolve the problem.
In the meantime, over-the-counter pain relievers can bridge the gap while the antibiotic does its work. Ibuprofen is particularly useful because it reduces both pain and inflammation.
Signs You Need Emergency Care
Most dental infections can wait for a next-day dentist appointment, but some situations are urgent. Get to an emergency room if you experience difficulty breathing or swallowing, swelling that’s spreading rapidly down your neck or under your jaw, a fever above 101°F that won’t come down, or trouble opening your mouth. These can signal that the infection is spreading into the tissues of your throat or neck, which can become life-threatening. A dental infection that causes systemic symptoms like high fever or spreading facial swelling needs antibiotics immediately, even before you can see a dentist.
For everything else, the priority is getting to a dentist. Antibiotics control the infection, but they don’t fix the underlying problem. Without dental treatment, the infection will likely return once you stop the medication.