Chlorhexidine is a widely used antiseptic and disinfectant in medical and nonmedical environments. The major advantage of chlorhexidine over most of the other compounds lies in its substantivity. It binds to hard and soft tissues in the mouth enabling it to act over a long period after use. Bacterial counts in saliva consistently drop to between 10 and 20% of baseline after single rinses and remain at this level for at least 7 hrs and probably more than 12 hrs.
Compared to its ubiquitous use, allergic contact dermatitis from chlorhexidine has rarely been reported and so its sensitization rate seems to be low. The prevalence of contact urticaria and anaphylaxis due to chlorhexidine remains to be unknown. Although rare chlorhexidine can cause immediate hypersensitivity, sometimes taking the form of acute urticaria that may result in anaphylactic shock which is even rarer.
The various tests which can be used to confirm the allergic reactions to chlorhexidine are as follows:
– Prick tests.
– Intradermal reactions.
– Sulfidoleukotriene stimulation test (CAST: Cellular antigen stimulation test).
– Patch test.
Hypersensitivity and other adverse reactions to chlorhexidine are rare, but its potential to cause anaphylactic shock is probably underestimated.
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