Parents have been warned to keep head lice treatments away from naked flames due to the risk of them igniting children's hair.
The Medicines and Healthcare products Regulatory Agency (MHRA) has issued a drug safety alert advising pharmacists to tell people about the risk of fires when they discuss options to treat head lice.
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Ten cases of serious burns associated with the use of head lice removal products have been reported to it since 2007.
The MHRA said those administering head lice treatments either to others or themselves should always read the instructions first as some have the potential to ignite when in the presence of an open flame - such as when lighting cigarettes.
Users who buy treatments in supermarkets or other shops where a pharmacist is not available to warn them of the risks need to be aware of the importance of reading the instructions that come with them to make sure they are used safely and correctly.
Dr Sarah Branch, deputy director of MHRA's vigilance and risk management of medicines (VRMM) division, said: "It's important parents and carers know always to keep away from a naked flame, including cigarettes, when using these head lice treatments.
"People can continue to use these head lice removal products safely - like all medical products, a simple check of the instructions will ensure safe, easy and effective use.
"Patient safety is our highest priority and we encourage people to report any incidents involving head lice removal products to MHRA using our yellow card scheme."