Chlorhexidine: The Good, the Bad and the Ugly

by Lou Shuman, DMD, CAGS, CEO and Founder of Cellerant Consulting


When you hear the word chlorhexidine it is easy to guess the first things that pop into your mind: stain, poor patient compliance, great bacterial killer, terrible taste, works well but causes calculus, and adds a lot more work. If you speak with a dental professional about chlorhexidine there are usually two camps of thought. Those who hate it and refuse to use it or those who choose to overlook the side effects and still use it.

Mostly, when dental professionals are asked about using chlorhexidine the response is never, “Because I love it!” Typically, you hear, “because it was taught to me in school,” or simply that there is no alternative. Using something just because we learned it in school is not good enough and there is an alternative that kills the same bacteria without the side effects. Let’s take a hard look at chlorhexidine: the good, the bad and the ugly.

The Good:
When used as designed

Chlorhexidine is a great bacterial killer.  There is no need to deny this as study after study has confirmed it. However, it has to use an incredibly high concentration to achieve results. It uses 1,200 parts per million to kill that bacteria.2 The rinse is so potent that it is not intended to be used longer than 2 weeks.

Chlorhexidine was introduced into dentistry in 1954; it is a broad-spectrum biocide effective against Gram-positive and Gram-negative bacteria.3  When designed it was meant to be used to temporarily help patients reverse gingivitis. Though effective for gingivitis, it is actually contraindicated for use with periodontal disease (see “The Ugly” section).

Even though it has many side effects, chlorhexidine, if the only option, can be safely used to treat gingivitis.  However, that is where “the good” stops. Too many dental professionals use chlorhexidine off-label and this is why the contraindications and safety concerns come into play.

The Bad:
The side effects

The main reason many dental professionals hate chlorhexidine is because of the side effects. We all know that it stains teeth.  Patients hate the stain as well as hygienists. It is kind of crazy that we clean a patient up and then give them a rinse that causes stain. Another very common side effect is additional calculus build-up. Again, this is not something that you want after scaling, prophies or surgeries.

Patients struggle to stay compliant with the rinse because of the taste. They can’t even rinse with water afterwards because it renders the rinse ineffective, and actually increases the bitterness!5 Then there is the lingering aftertaste and change to the taste buds.6 Most patients complain of a metal aftertaste that sticks around for several hours. Some patients experience an alteration in taste during treatment. In other rare instances, permanent taste alteration is experienced after the treatment has run its course.7

The Ugly:
Things you might not know

Side effects like staining and calculus aren’t ideal but they aren’t dangerous. Many dental professionals are willing to compromise with those side effects in an effort to get better results with treatment.  However, studies and real world cases show and tell us that we may want to reconsider this compromise. The concern for the severity of side effects are elevated when chlorhexidine gets used for anything other than what it was intended for: treating gingivitis.

Even with the treatment of gingivitis, there are unrealistic instructions and expectations for patients to follow. Since chlorhexidine is easily inactivated, it should be used 30 minutes after other dental products. It is deactivated by anionic compounds, including the anionic surfactants used in toothpaste.8 So patients should not rinse immediately after brushing.8 Furthermore, they must then avoid drinking, eating and smoking for at least one hour after use. There is also information that states that saliva and blood inactivate chlorhexidine.12, 15 So, how do we avoid saliva in the mouth? You can’t. Does it really even make sense to use chlorhexidine at all?

Serious side effects continue with their impact on fibroblast formation in the periodontal pocket.  The most astounding findings date back to 1991 where Dr. Charles D. Alleyn studied the re-establishment of lost connective tissue attachment to the root surface following periodontal therapy. Chlorhexidine damaged the fibroblasts, which are essential factors in reattachment.1 Reattachment is the entire purpose of scaling and root planing. Frankly, chlorhexidine is destroying the healing process. If we damage this, the healing phase takes longer, and the likelihood of a favourable outcome with therapy is low. This was the first of many subsequent studies. Finding out that a product we’ve been using for many years has been impacting patients negatively was described as a “critical event.”  Another study published in 2006 discusses the cytotoxic effect of chlorhexidine on cells, and cautions in using it for post SRP procedures like irrigation, due to it damaging the cells (like fibroblasts), which aid in the healing process.14 Yet, another study stated the higher concentration (≥0.04%) of CHX inhibits cell proliferation and, to a certain extent, affects cell morphology. Thus, “the application of CHX in the post-surgical antiseptic treatment of the oral cavity should be limited.”17 But in chlorhexidine’s defense, it was never meant to be used that way.

Off label uses in dentistry is where many of the serious issues originate.  Chlorhexidine was not created to be used with implants, periodontal therapy, or oral surgery. The FDA has reported more than 52 cases of anaphylaxis between 1998-2010 and this number has been increasing.7 The serious allergic reaction cases reported outcomes that required emergency department visits or hospitalizations to receive drug and other medical treatments. Two of these cases actually resulted in death. In both scenarios each patient had left the dental office after an extraction with chlorhexidine rinse to be used at home. As stated earlier, it takes 1200 ppm of chlorhexidine to achieve results.2 For this reason it should not be used with open wounds. In the cases where patients died, they both had open wounds and the uptake of the active ingredient was too high, inducing a severe allergic reaction.7

The Alternative

Many dental professionals feel “the bad” and “the ugly” of chlorhexidine outweigh the good, and they have looked for an alternative. Over 10 years ago a group of dentists who all shared this same feeling decided to develop an alternative. After years of research and development they came up with OraCare. The active ingredient, activated chlorine dioxide, kills the same bacteria as chlorhexidine but with only 44 parts per million.2 So it is safe to use everyday. Beyond just killing bacteria, activated chlorine dioxide has been shown to effectively remove biofilm, neutralize volatile sulfur compounds, and kills fungi and viruses.2 So, it can potentially offer additional benefits to patients without compromise, and without concern for safety. Chlorine dioxide is a gas, so it dissipates through the tissues quickly, and does not leave lingering side effects. There is no stain, no additional calculus build-up, and no negative impact on fibroblasts.
Dental hygienists have been choosing OraCare to replace chlorhexidine for nearly 10 years.  It utilizes activated chlorine dioxide and xylitol to help patients with a number of issues. The most common uses are bleeding gums, periodontitis, implant maintenance, dry mouth, bad breath, mouth sores, and the list goes on. If you are ready to make the switch, OraCare can provide you the good, and help you avoid “the bad” and “the ugly.”


  1. Alleyn, C. D., DDS, O’Neal, R. B., Strong, S. L., Scheidt, M. J., Van Dyke, T. E., & McPherson, J. C. (1991). The Effect of Chlorhexidine Treatment of Root Surfaces on the Attachment of Human Gingival Fibroblasts In Vitro. Journal of Periodontology, 62(7), 434438. Retrieved from
  2. An in Vitro Study Comparing a Two-Part Activated Chlorine Dioxide Oral Rinse to Chlorhexidine. Perio Implant Advisor, 15 Jan. 2015,
  3. Carolyne Horner, Damien Mawer, Mark Wilcox, Reduced susceptibility to chlorhexidine in staphylococci: is it increasing and does it matter?, Journal of Antimicrobial Chemotherapy, Volume 67, Issue 11, November 2012, Pages 2547–2559,
  4. “Chlorhexidine (Oral Route) Side Effects. “Mayo Clinic, Mayo Foundation for Medical Education and research, 1 Feb. 2020,
  5. “Chlorhexidine Facts.” Chlorhexidine Facts: Mechanism of Action, 2019,
  6. Clinical implications of the growth-suppressive effects of chlorhexidine at low and high concentrations on human gingival fibroblasts and changes in morphology. Marzena Wyganowska-Swiatkowska, Malgorzata Kotwicka, Paulina Urbaniak, Agnieszka Nowak, Ewa Skrzypczak-Jankun, Jerzy Jankun Int J Mol Med. 2016 Jun; 37(6): 1594–1600. Published online 2016 Apr 7. doi: 10.3892/ijmm.2016.2550
  7. FDA warns about rare but serious allergic reactions with the skin antiseptic chlorhexidine gluconate. S. Food & Drug Administration. 9 Feb. 2017,
  8. Ioannis Tsourounakis, Angela A. Palaiologou‐Gallis, Diana Stoute, Pooja Maney and Thomas E Lallier, Effect of Essential Oil and Chlorhexidine Mouthwashes on Gingival Fibroblast Survival and Migration, Journal of Periodontology, 84, 8, (1211-1220), (2013).
  9. Kolahi J, Soolari A. Rinsing with chlorhexidine gluconate solution after brushing and flossing teeth: a systematic review of effectiveness. Quintessence Int. 2006;37(8):605–612.
  10. Schmidt, V. Zyba, K. Jung, S. Rinke, R. Haak, R.F. Mausberg and D. Ziebolz, Effects of octenidine mouth rinse on apoptosis and necrosis of human fibroblasts and epithelial cells – an in vitro study , Drug and Chemical Toxicology, 10.1080/01480545.2017.1337124, 41, 2, (182-187), (2017).
  11. I. R. Teixeira, A. M. L. Denadai, R. D. Sinisterra and M. E. Cortés, Cyclodextrin modulates the cytotoxic effects of chlorhexidine on microrganisms and cells in vitro , Drug Delivery, 10.3109/10717544.2013.879679, 22, 3, (444-453), (2014).
  12. Mehmet Sağlam, Uğur Arslan, Şerife Buket Bozkurt and Sema S. Hakki, Boric Acid Irrigation as an Adjunct to Mechanical Periodontal Therapy in Patients With Chronic Periodontitis: A Randomized Clinical Trial, Journal of Periodontology, 84, 9, (1297-1308), (2013).
  13. “The Advantages and Disadvantages of Chlorhexidine Mouthwash.” 1 Feb. 2020,
  14. Polimeni, G., Xiropaidis, A. V., & Wikesjö, U. M. (2006). Biology and Principles of Periodontal Wound Healing/Regeneration. Periodontology 2000, 41, 30-47. Retrieved from
  15. Van Maanen-Schakel NW, Slot DE, Bakker EW, Van der Weijden GA. The effect of an oxygenating agent on chlorhexidine-induced extrinsic tooth staining: a systematic review. Int J Dent Hyg. 2012;10(3):198–208. doi:10.1111/j.1601-5037.2012.00555.x
  16. Van Strydonck DA, Demoor P, Timmerman MF, van der Velden U, van der Weijden GA. The anti-plaque efficacy of a chlorhexidine mouthrinse used in combination with toothbrushing with dentifrice. J Clin Periodontol. 2004;31(8):691–695. doi:10.1111/j.1600-051X.2004.00546.
  17. Wyganowska-Swiatkowska, M., Kotwicka, M., Urbaniak, P., Nowak, A., Skrzypczak-Jankun, E., & Jankun, J. (2016). Clinical implications of the growth-suppressive effects of chlorhexidine at low and high concentrations on human gingival fibroblasts and changes in morphology. International Journal of Molecular Medicine, 37, 1594-1600. Retrieved from

About the Author

Lou Shuman is the CEO of Cellerant Consulting Group, dentistry’s leading corporate incubator and accelerator. He is a venturer in-residence at Harvard’s i-Lab, co-founder of LightForce Orthodontics, a member of the Oral Health advisory board and founder of the Cellerant Best of Class Technology Awards. He was selected in 2021 by Global Summits Institute one of the World’s Top 100 Doctors.