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Supporting Your Practice

Can Chlorhexidine (CHX) Provoke an Allergic Reaction?

Chlorhexidine has been used by dentists, medical doctors, and the general public for decades. Known for its disinfecting and antiseptic properties, CHX is commonly used as a topical skin disinfectant, a mouthwash, and in pharmaceutical products. But for some, patients and care providers alike, Chlorhexidine can cause an allergic reactions ranging from moderate to deadly.

Dr. Mark Donaldson is back on Oasis to explore CHX and share information that dentists need to know to prevent allergic reactions in patients under their care.

About Dr. Mark Donaldson

Mark Donaldson, BSP, RPH, ACPR, PHARMD, FASHP, FACHE, is a Clinical Professor in the Department of Pharmacy at the University of Montana in Missoula, Clinical Associate Professor in the School of Dentistry at the Oregon Health & Sciences University in Portland, Oregon and Adjunct Professor, in the Faculty of Dentistry at the University of British Columbia.

He has a special interest in dental pharmacology and has lectured internationally to both dental and medical practitioners. He has spent the last 20 years focusing on dental pharmacology and dental therapeutics and is a leader in the field. Dr. Donaldson has published numerous peer-reviewed works and textbook chapters. He has practiced as a clinical pharmacy specialist, clinical coordinator and director of pharmacy services at many healthcare organizations in both Canada and the United States. 

Dr. Donaldson is also the 2019 recipient of the Special Friend of Canadian Dentistry Award conferred on an individual or organization outside of the dental profession in appreciation for exemplary support or service to Canadian dentistry and/or to the profession as a whole.

During this discussion, Dr. Donaldson talks about:

  • The history of CHX, when it was introduced into dental practices.
  • Contemporary safety statistics and recommendations.
  • Challenges, potentially due to over use.
  • Typical uses for in dentistry.
  • Products on the market that typically contain CHX.
  • Types of allergic reactions caused by CHX.
  • Steps dentists can take to avoid an allergic reaction.
  • Where to look for allergic symptoms (urticaria or hives) outside of the mouth.
  • Counselling patients on the hazards of overexposure to CHX.

Access the full text of the article (PDF)

Read/download the transcript of the conversation (PDF)

Oasis Moment/Preview (1.38″)

Full Conversation (13.49″)

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Until next time!

CDA Oasis Team



  1. David Okamura May 18, 2019

    A much safer and more effective product is made by American Biotech Labs (ablsilver.com) in Utah. They have more than 60 research studies that confirm that their silver sol containing products in liquid and gel form are unsurpassed in killing all micro-organisms (bacteria,viruses fungi) and even the antibiotic resistant strains such as MRSA, c.difficile, Malaria can also be treated very effectively. I have been using their products in my dental practice for over 10 years with outstanding outcomes for my patients and myself and family. Dr. Andrew Willoughby in Prince George BC first encountered ABL products in 2004. He has done a lot of research with their products and found that their silver sol solution has had profound effect on patient outcomes surgically, periodontally, endodontically, and restoratively. He has been involved with ABL since 2009. Unfortunately, their products are not readily available and very few are even aware of the existence of such a powerful antibiotic. Its effect on wound healing is almost miraculous. Their Tooth Gel contains their silver sol solution and Xylitol-a winning combination- The beauty of using their liquid 10ppm solution as a mouth rinse is not only does it reduce the micro-organisms in your mouth, but it can be ingested as a prophylactic for general health without affecting the gut flora. Its safety is well documented.

  2. Hilary Pada June 13, 2019

    Could you please comment on the effects on our water sources of having broad use of spitting silver sol containing products down the drain. What is the impact on lakes, rivers and streams, as well as the needed bacterial colonies for safe waste-water treatment in our communities?

    1. David Okamura June 13, 2019

      Hi Hillary
      I would recommend that you contact ABL (American Biotech Labs) ablsilver.com directly for their response. I do know that there are studies of the effect of sterilizing dental lines with their silver sol solution which demonstrate that it is a very effective anti-microbial – better results than is possible with gluteraldehyde. Dr Andrew Willoughby of Prince George BC has done some studies with ABL silver in his practice with really positive outcomes He might be a source to answer your concerns

      Dave Okamura

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