Is 2,000mg Of Keflex The Right Dose Before A Dental Appointment?

In our latest question and answer, the pharmacist discusses the use of Keflex (cephalexin) as a pre-dental antibiotic.


is it safe to take 2000mg of Keflex at once? That is what my surgeon advises. This is premed before dental work. It seems excessive.

Asked by Dave On Oct 20, 2022

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Oct 21, 2022
Last updated Apr 19, 2024

Key points

  • Pre-dental antibiotics are recommended for certain individuals undergoing dental procedures to prevent bacterial endocarditis.
  • Several antibiotic regimens are recommended for pre-dental use, including Keflex (cephalexin) 2,000mg, 30 to 60 minutes before a procedure.


Although studies show mixed results on the true benefit of dosing with antibiotics before a dental procedure as a prophylactic measure against infection, they are commonly prescribed for certain individuals to prevent bacterial endocarditis.

The American Heart Association journal 'Circulation' provides a good, succinct summary, of their recommendation:

We continue to recommend VGS IE [Viridans Group Streptococcal Infective Endocarditis] prophylaxis only for categories of patients at highest risk for adverse outcome while emphasizing the critical role of good oral health and regular access to dental care for all. Randomized controlled studies to determine whether antibiotic prophylaxis is effective against VGS IE are needed to further refine recommendations.
Circulation . 2021 May 18;143(20):e963-e978.

Who Is Recommended To Take Pre-Dental Antibiotics?

As mentioned, pre-dental antibiotics are sometimes recommended for those who have cardiac conditions that put them at high risk for complications if infective endocarditis (an infection caused by bacteria that enter the bloodstream and settle in the heart) were to occur. Individuals were pre-existing heart conditions may also be more likely to develop infective endocarditis in the first place.

The American Heart Association classifies the following conditions as the highest risk for complications from infective endocarditis:

  • Prosthetic cardiac valve or material
  • History of infective endocarditis
  • Congenital heart disease
  • Cardiac transplant recipients who develop cardiac valvulopathy (when any valve in the heart has been damaged)

The nature of the dental work you are getting needs to be taken into consideration as well here.

The greatest risk of infective endocarditis is generally considered to be for dental procedures that involve manipulation of gingival tissue (i.e, gums). Procedures include:

  • Tooth extractions
  • Drainage of a dental abscess
  • Routine dental cleaning

Procedures that only include imaging (like X-rays) do not require prophylactic antibiotics.

What Antibiotics Are Recommended Before A Dental Appointment In High-Risk Individuals And What Are The Doses?

Getting into the main part of your question here, let's go over the recommended 'pre-dental' antibiotics options if your dentist has recommended antibiotic prophylaxis.

The first-line recommendation for individuals with cardiac risk factors undergoing dental procedures is:

  • Amoxicillin: Adults: 2 grams; children: 50 mg/kg - 30 to 60 minutes before dental procedure

If amoxicillin can't be used or there is a medical reason why it is not the best option, alternative recommended pre-dental antibiotic regimens include:

  • Keflex (cephalexin): Adults: 2 grams; children: 50 mg/kg - 30 to 60 minutes before dental procedure
  • Azithromycin or clarithromycin: Adults: 500mg; children: 15 mg/kg - 30 to 60 minutes before dental procedure
  • Doxycycline: Adults: 100mg; children: (<45 kg, 2.2 mg/kg >45 kg, 100 mg) - 30 to 60 minutes before dental procedure

As you can see, Keflex (cephalexin) is a recommended pre-dental antibiotic for those at high risk for infective endocarditis. For adults, since Keflex is available in 500mg capsules, the usual recommended dose is:

  • Take (4) Keflex 500mg capsules (2,000mg) by mouth 30 to 60 minutes before the dental procedure

Final Words

Although taking 2,000mg of Keflex as one dose certainly seems like a lot based on what the usual dose of the antibiotic is (which is generally 250-500mg three to four times daily), it is what the guidelines recommend as a pre-dental antibiotic if you are someone that is in one of those high-risk categories.

Thanks for reaching out to us!


  • 2015 ESC Guidelines for the management of infective endocarditis: The Task Force for the Management of Infective Endocarditis of the European Society of Cardiology (ESC). Endorsed by: European Association for Cardio-Thoracic Surgery (EACTS), the European Association of Nuclear Medicine (EANM), PubMed
  • Prevention of Viridans Group Streptococcal Infective Endocarditis: A Scientific Statement From the American Heart Association, PubMed
  • Prevention of infective endocarditis, PubMed
  • Antibiotic prophylaxis for infective endocarditis: a systematic review and meta-analysis., PubMed

About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 13 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical, program development, and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication-related questions! Dr. Brian Staiger also has herbalist training and educational certificates in the field of medical ethnobotany. Feel free to send him an email at [email protected]! You can also connect with Dr. Brian Staiger on LinkedIn.

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