Safety update on gentian violet antiseptic
HSA is aware that Health Canada had issued a safety alert in June 2019 to warn that gentian violet (GV)-containing antiseptic may potentially increase the risk of carcinogenicity. To ensure safe use of GV-containing products in Singapore, HSA has conducted a benefit-risk assessment of these products.
About gentian violet1-5
GV is an antiseptic with antibacterial, antifungal and antihelminthic properties. The documented therapeutic uses of topical GV-containing products include the treatment of bacterial skin infections and fungal infections. Although GV’s exact mechanism of action has not been elucidated despite its long history of use (more than a century), several mechanisms have been postulated, including the formation of free radicals and the induction of oxidative stress in bacteria. GV has been reported to be effective against Candida albicans and Gram-positive bacteria, particularly Staphylococcus sp, due to its ability to penetrate the bacterial cell wall. A systemic literature review also suggested that GV could be used to eradicate or disrupt biofilms in ear, nose, and throat (ENT) infections.
Safety alert from Health Canada6-7
In June 2019, Health Canada issued a safety alert on the potential risk of carcinogenicity with GV-containing products. The alert was based on Health Canada’s review of available animal studies in the scientific literature, suggesting that oral exposure to GV in animals has been associated with the development of cancer.
In Canada, GV-containing products have been reported to be used on skin, mucous membranes (e.g. in nose, mouth and vagina), open wounds and on the nipple of a nursing mother to treat oral thrush in infants. Although Health Canada did not receive any cancer reports with the use of GV products, the agency highlighted its concerns over the potential oral exposure in infants as it had received adverse event reports (non-cancer) associated with the use of GV for oral thrush in two infants (aged two and five months). In response, the manufacturer of the only registered GV product (Gentiane Violet Liquid Topical) voluntarily discontinued the sale of the product in Canada.
Carcinogenicity of gentian violet5, 8-12
HSA has reviewed the available scientific literature and noted that current evidence on the carcinogenicity of GV has mainly been observed with high-dose oral exposure to GV in animal studies. Tumours were observed in various organs (e.g. liver, thyroid, reproductive organs) following two years of oral exposure to mid to high doses (up to 600ppm) of GV in rats and mice. There was insufficient evidence to suggest that the same cancer-causing effect with high-dose oral exposure to GV in animals could be extrapolated to the low-dose external application of GV in humans. To date, there have also been no local and international reports of cancer definitively linked with GV use in humans.
Local situation and HSA’s advisory
In Singapore, GV is not a commonly used antiseptic, possibly due to the advent of newer and more effective antiseptics. However, there are some clinicians who use GV topically for the short-term management of certain acute conditions, such as skin erosion conditions, stoma care and ear infections, when other therapeutic options may not be as effective.
Based on available data, the current evidence on potential risk of carcinogenicity with GV appears to be mainly limited to high-dose oral exposure to GV in animal studies. Nonetheless, healthcare professionals need to be aware of this risk. As GV remains a useful therapeutic option for certain acute conditions, to ensure safe use of the product, healthcare professionals are reminded that GV-containing antiseptic is limited to short-term external use only.
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- https://oehha.ca.gov/media/downloads/crnr/gentianviolethid011719.pdf (Jan 2019)
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