Amoxicillin is the first-line antibiotic for most tooth infections, recommended at 500 mg three times a day for three to seven days. If you’re allergic to penicillin, several alternatives exist. But antibiotics alone don’t cure a tooth infection. They control the bacteria while your dentist addresses the underlying problem.
Amoxicillin: The Preferred First Choice
The American Dental Association’s clinical guidelines recommend amoxicillin as the top choice for tooth infections in adults with healthy immune systems. It’s preferred over its close relative, penicillin V, because it works against a broader range of the bacteria found in dental infections and causes fewer stomach-related side effects. The standard dose is 500 mg, taken three times a day.
Penicillin V is the second option in the same family, dosed at 500 mg four times a day. It works well but requires an extra daily dose and covers slightly fewer bacterial types. Both medications are prescribed for three to seven days, and current ADA guidance says you should stop taking them 24 hours after your symptoms resolve, even if that’s before you finish the full course. Your dentist should check in with you within three days of starting antibiotics, either by phone or in person.
Options if You’re Allergic to Penicillin
A penicillin allergy doesn’t leave you without options. Several other antibiotic classes can handle tooth infections:
- Azithromycin: A common alternative that works differently from penicillin-type drugs, making it safe for most people with penicillin allergies.
- Cephalexin: Part of the cephalosporin family, which is chemically related to penicillin. Most people with a mild penicillin allergy tolerate cephalosporins fine, but if your allergy involved a severe reaction like throat swelling or anaphylaxis, your dentist will likely choose something else.
- Metronidazole: Particularly effective against the oxygen-avoiding bacteria that thrive deep inside abscesses. Sometimes prescribed on its own, sometimes paired with another antibiotic.
- Clindamycin: Generally reserved for stubborn infections that haven’t responded to other antibiotics rather than used as a first choice.
Your dentist picks among these based on the type and severity of your infection, your allergy history, and whether you’ve recently taken antibiotics that didn’t work.
When Two Antibiotics Are Used Together
For more severe or persistent infections, dentists sometimes prescribe amoxicillin and metronidazole together. The logic is straightforward: tooth infections involve a mix of bacterial species. Amoxicillin handles one group well, while metronidazole targets the anaerobic bacteria (the kind that grow in the oxygen-free environment deep inside an abscess or below the gumline). The combination covers more ground than either drug alone. Clinical trials have consistently shown this pairing improves outcomes compared to a single antibiotic, particularly for serious periodontal infections.
Antibiotics Don’t Replace Dental Treatment
This is the most important thing to understand: antibiotics manage the infection, but they don’t fix the source. A tooth infection starts because bacteria have reached the inner pulp of the tooth or the tissue around the root, usually through deep decay, a crack, or gum disease. Antibiotics can knock down the bacterial load and prevent spread, but the infection will return if the damaged tooth isn’t treated.
The ADA’s current guidelines are clear on this point. For most tooth infections, including inflamed pulp, irritation around the root tip, and localized abscesses, dentists should prioritize hands-on treatment first. That means procedures like root canal therapy, draining an abscess, or removing the infected portion of pulp tissue. Antibiotics should be added only when the infection has progressed beyond the tooth itself, with signs like fever or general malaise indicating it’s spreading.
If your dentist can’t see you right away, a prescription for antibiotics buys time. But it’s a bridge to treatment, not a substitute for it.
Why the Right Antibiotic Matters More Than Ever
Antibiotic resistance is a growing concern in dentistry. Several of the bacteria commonly involved in tooth infections are developing ways to resist the drugs used against them. Some species now produce enzymes that break down penicillin-type antibiotics before they can work. Others have altered their cell structures so the drugs can’t latch on effectively. Resistance to metronidazole is also rising among certain gum-disease bacteria, which complicates treatment for periodontal infections.
This is one reason the ADA now emphasizes shorter courses (three to seven days, stopping once symptoms resolve) rather than the longer courses that used to be standard. Taking antibiotics you don’t need, or taking them longer than necessary, accelerates resistance. If your dentist determines that hands-on treatment alone can handle your infection without antibiotics, that’s not them being dismissive. It’s the current best practice.
Signs a Tooth Infection Needs Urgent Care
Most tooth infections stay localized and respond well to dental treatment with or without antibiotics. But in rare cases, the infection can spread into the jaw, throat, neck, or bloodstream. If you develop a fever along with facial swelling and can’t reach your dentist, go to an emergency room. Difficulty breathing or swallowing is especially urgent, as these can signal the infection is compressing your airway. Left unchecked, a spreading dental infection can lead to sepsis, a life-threatening condition where the infection triggers a dangerous whole-body inflammatory response.
Even without those alarming symptoms, worsening pain, swelling that’s expanding, or a fever above 101°F after starting antibiotics are all reasons to seek care sooner rather than later. Antibiotics typically produce noticeable improvement within 48 to 72 hours. If you’re not feeling better in that window, the antibiotic may not be the right match for the bacteria causing your infection, and your dentist needs to reassess.