Antibiotics For Tooth Infection


Tooth infection is very often accompanied by severe pain: those who have felt it can vouch for its severity, and some even consider it to be one of the worst kinds of pain to be felt. As much as it is important to take care of your teeth to avoid infections, sometimes it is too late for prevention, and actions must be taken to control the infection and avoid its spreading, and this is where antibiotics can be extremely helpful.

Ever since their discovery, antibiotics have been widely used, including in Dentistry, to treat infections: dental cavities, pulp necrosis and periodontal disease (gum disease) are among the most common causes when it comes to the oral cavity.¹ But the myriad of antibiotic types can often confuse patients and doctors alike: which one to prescribe? Is antibiotic therapy enough to cure dental infections? Let’s find out in this article.

Causes of tooth infection

Tooth infections, known also as odontogenic infections, can usually be traced back to four causes: cavities, pulp necrosis, dental trauma and periodontal disease.¹

Cavities (tooth decay) are a chronic disease that demineralizes the hard tissues (enamel, dentin and, if it affects the root, cementum) and progressively destroys them.² This happens because cariogenic bacteria start producing acids that degrade the mineral layers, as part of their metabolism.² Lack of proper hygiene and a diet rich in sugar and starch can lead to tooth decay.²

Once bacteria reach the soft tissue inside the tooth, called pulp, it starts an inflammation process known as pulpitis.³ Pulpitis can happen due to untreated cavities, or due to trauma (exposing the dental pulp to the bacteria that exist inside the oral cavity)³. This condition is very painful and can lead to pulp necrosis, a process in which the pulp tissue dies: the pain stops, but not the infection, that continues to spread into the periapical region.³ Periapical infections can manifest as abscesses, a pus collection that causes pain and swelling either internally (intra oral) or externally if very exuberant.³

Periodontal disease is another factor that can cause tooth infection.³ This disease starts affecting the gingiva as gingivitis, and it can evolve to periodontitis, a more severe type of infection that affects other support tissues (like the alveolar bone).³ Lack of hygiene can result in dental plaque and dental calculus, factors that aggravate periodontal disease, but other factors can also influence in how a patient develops this condition: patients who smoke tobacco and/or have diabetes mellitus are more susceptible to develop gum disease and usually have a poorer prognosis.³

Dental infections usually present with pain and swelling of the area.¹ Most commonly, they are caused by Gram-positive cocci (about 65% of all infections), though they can also be caused by Gram-negative bacilli (about 25% of cases).¹ There’s no gender preference, but most individuals who have dental infections tend to be younger, between ages 21 to 40.¹

It is extremely important to take odontogenic infections seriously: although most of the time they are contained by the alveolar bone into a small region, they have the potential to spread into deeper tissues and even systemically.⁴ Some of the known consequences of tooth infections are:

  • Osteomyelitis¹
  • Cavernous sinus thrombosis⁴
  • Airway obstruction⁴
  • Ludwig angina³
  • Retropharyngeal or parapharyngeal abscesses³
  • Brain abscess⁴
  • Orbital abscess¹
  • Vision loss¹
  • Mediastinitis⁴
  • Carotid infection¹
  • Septicemia¹
  • Bacterial endocarditis³

When to prescribe an antibiotic?

Although most people associate treating infections with antibiotics, this isn’t always the case when it comes to dental infections: eliminating the source of infection is often the most effective way to combat the disease, and antibiotics are prescribed as an adjuvant therapy.⁴

But when should antibiotics be prescribed?

The American Dental Association (ADA) has elaborated a guideline to orient professionals regarding antibiotic prescription.⁵ If there are no signs and symptoms of a systemic infection and if dental treatment is readily available, the ADA found there is no significant improvement in pain or a better outcome if antibiotics are prescribed; however, the undesirable side effects of antibiotic use (bacterial resistance and adverse effects) are still considerable and the possible benefits of antibiotic therapy do not outweigh the risks.⁵

  • If the patient only presents with pain, and they are immunocompetent (those not affected by systemic diseases and conditions such as cancer, HIV, or organ transplantation, among others), antibiotics should not be prescribed unless the patient has no readily available dental care.⁵
    • In this case, other drugs can be prescribed to control pain (like ibuprofen and acetaminophen), and dental treatment in the form of root canal treatment (RCT) and drainage are preferable.⁵
  • If there is pain and swelling in an immunocompetent patient, but no systemic involvement (fever, malaise), the patient should be referred to a dentist for treatment as soon as possible and antibiotic therapy should not be prescribed.⁵
    • If the patient cannot access dental care easily, antibiotic therapy should be considered.
  • If there is pain, swelling and systemic involvement, antibiotics should be prescribed even if the patient is immunocompetent.⁵
  • If the patient is immunocompromised, antibiotic therapy is a priority along with dental treatment, regardless of signs and symptoms.⁵

Antibiotics commonly prescribed

There are many types of antibiotics to choose from. Different classes have different action mechanisms and can be prescribed to different types of bacteria.1

  • Beta-lactamase antibiotics: this class contains penicillin, cephalosporin and their derivatives. Examples include amoxicillin, ampicillin and penicillin V.
  • Nitroimidazoles: one example is metronidazole.
  • Macrolides: this class of antibiotic drugs contains erythromycin, azithromycin, and clarithromycin.
  • Lincosamides: the most common example is clindamycin.
  • Fluoroquinolones: this class contains ciprofloxacin and moxifloxacin.
  • Tetracyclin.

Different drugs can be prescribed according to the infection present: most of the time, a broad-spectrum drug can be prescribed to solve an infection, but that isn’t always the case; the first choice of antibiotic can fail, or the patient might be allergic.¹ In this case, other drugs should be considered differently for children and adults.¹

Antibiotic use in children¹

DrugWhen to use
AmoxicillinFirst choice
Amoxicillin + clavulanic acidFailure of first choice
ClindamycinAllergic to penicillin and derivatives
CephalexinNeed for a broad-spectrum drug
MetronidazoleAgainst anaerobic bacteria

Antibiotic use in adults¹

DrugWhen to use
AmoxicillinFirst choice (oral medication)
CephalexinAllergic to penicillin and derivatives
Ampicillin or cefazolin/ceftriaxoneUnable to take oral medication (can be prescribed through an IV or intramuscular injection)
ClindamycinAllergic to penicillin and derivatives
Azithromycin/clarithromycinAllergic to penicillin and derivatives
Cefazolin/ceftriaxoneAllergic to penicillin and derivatives and unable to take oral medication

Patients who are pregnant should inform a dentist before being prescribed antibiotics: some of them present risk to the foetus.¹ Ciprofloxacin and moxifloxacin have been shown to be detrimental to cartilaginous growth in rats, clarithromycin can induce miscarriages, and both doxycycline and tetracycline can permanently stain the teeth of the developing foetus.¹ Safe alternatives like amoxicillin and cephalexin can be prescribed.¹

Alternative and complementary treatments

Prescribing antibiotics is only part of the treatment, and eliminating the infection is the most important step of it all.¹

Root canal treatment (RCT) is used when there is irreversible damage to the pulp, pulp necrosis or periapical infections (like an abscess).⁵ Drainage of an abscess can be performed if it is large enough to not be drainable through the root canal.³ If the patient opts to do so, extraction of the tooth instead of RCT is an option, and tooth extraction can also be performed if the tooth is unable to be properly restored.³

Periodontal disease can be treated through scaling, better hygiene and, sometimes, associating medication (like antibiotics) with the previous steps.

In some cases, low-level laser therapy (LLLT) and photodynamic therapy (PDT) can be used as adjuvant treatment in infections: they can reduce bacterial proliferation and stimulate healing and reduce inflammation locally.¹


Antibiotics can be prescribed to treat dental infections, but they aren’t always necessary. Some of the most common causes of tooth infection include cavities (tooth decay), dental trauma, pulp necrosis, and periodontal disease. Most of the time, treatment includes dental care (like drainage of abscesses and root canal treatment) instead of antibiotic prescription. Patients who are immunocompetent (who have no history of systemic diseases) and present with only a localised infection should not be prescribed antibiotics, recent guidelines of the American Dental Association says; in case there is systemic infection, immunocompetent patients should be prescribed antibiotics; immunosuppressed patients should always receive antibiotic treatment. The most commonly prescribed drugs are amoxicillin and, to those allergic to penicillin, clindamycin should be used instead. Along with antibiotic drugs, root canal treatment, drainage, and even low-level laser therapy and photodynamic therapy can be used to treat odontogenic infections.


  1. Ahmadi H, Ebrahimi A, Ahmadi F. Antibiotic Therapy in Dentistry. International Journal of Dentistry [Internet]. 2021 Jan 28;2021:6667624. Available from:
  2. Rathee M, Sapra A. Dental Caries [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2020. Available from:
  3. Erazo D, Whetstone DR. Dental Infections [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2020. Available from:
  4. Ogle OE. Odontogenic Infections. Dental Clinics of North America. 2017 Apr;61(2):235–52.
  5. Lockhart PB, Tampi MP, Abt E, Aminoshariae A, Durkin MJ, Fouad AF, et al. Evidence-based clinical practice guideline on antibiotic use for the urgent management of pulpal- and periapical-related dental pain and intraoral swelling. The Journal of the American Dental Association [Internet]. 2019 Nov;150(11):906-921.e12. Available from:
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Isabela Araújo Rosa

Doctor of Dental Surgery - DDS, Universidade Federal de Goiás, Brazil

Isabela is a board certified dentist in Brazil, with a background in Oral and Maxillofacial Pathology, Bioethics and Oral Medicine, and previous experience with medical writing and medical communication.

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