Paraffin-based skin creams may be linked to hundreds of deaths, a senior firefighter has warned.
Chris Bell, a watch commander with West Yorkshire Fire and Rescue Service, said the creams - used to treat a variety of skin conditions, including eczema and psoriasis - are safe to use.
But he warned they can become flammable when they soak into fabrics, clothing, bandages and dressings, then come into contact with a cigarette, naked flame or other heat source.
"Hundreds of thousands of people use them, we're not sure how many fire deaths might have occurred but it could be into the hundreds," he told the BBC.
His comments come after an investigation by BBC 5 live Investigates and Inside Out Yorkshire and Lincolnshire found only seven of 38 products containing paraffin that are licensed in the UK carry warnings on their packaging.
"People are using paraffin-based skin products to treat eczema and psoriasis and various other skin creams, putting it all over their bodies and different parts of themselves - treating themselves for those different skin conditions," Mr Bell told 5 live.
"But unfortunately, that cream can get into fabrics, clothing, bandages and dressings, and become flammable.
"The creams are safe to use in their own right, but if that person is exposed to a naked flame or some other heat source, they can go up."
The Medicines and Healthcare products Regulatory Agency advises patients using paraffin-based products not to smoke, use naked flames, or go near anything that may cause a fire while creams are in contact with dressings or clothing.
Its advice states: "Patients' clothing and bedding should be changed regularly -- preferably daily -- because emollients soak into fabric and can become a fire hazard."