What are the implications of a chlorhexidine (CHG) allergy?

From the Guidelines

Chlorhexidine allergies should be taken seriously and avoided in all products, including mouthwashes, skin preparations, and certain medical devices, due to the risk of severe anaphylaxis, as highlighted in the most recent study from 2019 1. If you have a chlorhexidine allergy, it is crucial to inform healthcare providers before any medical procedure and wear a medical alert bracelet to ensure emergency personnel are aware of this allergy. Some key points to consider include:

• Alternative antiseptics such as povidone-iodine, alcohol-based solutions, or benzalkonium chloride can be used instead of chlorhexidine products.
• For oral hygiene, consider using diluted hydrogen peroxide rinses or essential oil-based mouthwashes instead of chlorhexidine products.
• The immune system mistakenly identifies chlorhexidine as harmful, triggering the release of histamine and other inflammatory chemicals, which can lead to anaphylaxis, as noted in a study from 2014 1.
• The prevalence of chlorhexidine allergies has increased as the antiseptic has become more widely used in healthcare settings, so vigilance is important, especially if you've had previous unexplained reactions during medical procedures, as discussed in a study from 2009 1.
• In cases of emergency surgery where no information is available, use of regional, inhalational, or both anaesthetic techniques should be favored to minimize i.v. drug exposures, and use of latex, chlorhexidine, NMBAs, and antibiotics from the penicillin or cephalosporin group should be avoided if possible, as recommended in the 2019 study 1.
• If chlorhexidine is contraindicated due to sensitivity or allergy, povidone-iodine solution (preferably with alcohol) is a reasonable substitute and should be used, as suggested in the 2020 guideline 1.

From the FDA Drug Label

Warnings For external use only Allergy alert This product may cause a severe allergic reaction. Symptoms may include: wheezing/difficulty breathing shock facial swelling hives rash If an allergic reaction occurs, stop use and seek medical help right away Do not use if you are allergic to chlorhexidine gluconate or any other ingredient in this preparation

• Chlorhexidine allergy is a serious concern, as the product may cause a severe allergic reaction.
• Symptoms of an allergic reaction to chlorhexidine include:
  • Wheezing/difficulty breathing
  • Shock
  • Facial swelling
  • Hives
  • Rash
• If an allergic reaction occurs, stop use and seek medical help right away 2.

From the Research

Chlorhexidine Allergy Overview

• Chlorhexidine is a synthetic bisbiguanide antiseptic that has been used in healthcare since 1954 3.
• Allergy to chlorhexidine has been increasingly reported, particularly in perioperative and medical procedural settings, with hypersensitivity reactions ranging from mild cutaneous reactions to anaphylaxis or death 3, 4, 5.

Clinical Manifestations and Diagnostic Methods

• Symptoms of chlorhexidine allergy can range from mild skin symptoms to life-threatening anaphylaxis 4, 5, 6.
• Testing for chlorhexidine allergy is based on skin testing and in vitro testing, with skin prick testing and specific IgE having high sensitivities and specificities 6.

Management and Preventive Measures

• Severe cases of chlorhexidine allergy can be managed with intravenous fluids, steroids, and epinephrine (adrenaline) 7.
• Allergy risks can be mitigated by better warning and training clinicians, recording and screening patient histories for CHX presensitization from prior exposure, and prestocking procedure carts and rooms with injectable epinephrine and other rapidly acting anti-inflammatory medications 7.
• Prompt referral to a specialist allergy centre ensures appropriate investigations, diagnosis, and management of chlorhexidine allergy 4.

Product-Related Risks

• Many products and medical devices contain chlorhexidine, sometimes with poor labeling, which can lead to accidental or recurrent reactions in chlorhexidine-allergic patients 3, 7, 4.
• Catheters, semisolids, and fluid products are common categories of medical products associated with allergic reactions to chlorhexidine 7.