Health experts have moved to reassure British vapers in the wake of a severe respiratory illness that has killed at least five people and hospitalised many more in the US.

More than 450 possible cases – all linked to vaping – among otherwise “healthy young people” are being investigated, US officials said on Friday.

They have reported that affected individuals have experienced respiratory symptoms including a cough, shortness of breath, and fatigue. Some also experienced vomiting and diarrhoea. Symptoms worsened over a period of days or weeks before admission to hospital.

The outbreak has led to fears that vapers in the UK could also be affected. However, Martin Dockrell, head of Tobacco Control at Public Health England, drew a distinction between vaping in the US and the UK. He said reports suggested that most cases in the US had been linked to people using illicit vaping fluid, bought on the streets or homemade, some containing cannabis products, like THC, or synthetic cannabinoids, like spice.

“Unlike the US, all e-cigarette products in the UK are tightly regulated for quality and safety by the Medicines and Healthcare Products Regulatory Agency and they operate the yellow card scheme, encouraging vapers to report any bad experiences,” he said.

Deborah Arnott, the chief executive of the health charity Action on Smoking and Health, said that to date no serious side-effects had been reported in the UK. “In Britain, you can check on the Medicines and Healthcare Products Regulatory Agency (MHRA) website whether the product you’re using has been notified and can be legally sold.”

This point was backed by Prof Linda Bauld, a public health expert at Edinburgh University. “It seems highly unlikely that widely available nicotine-containing vaping products, particularly of the type regulated in Europe, are causing these cases,” she said. “All the evidence to date suggests that illicit marijuana vaping products (THC oils) are the cause. In particular, a compound called tocopherol acetate may be the culprit.”

Paul Aveyard, a professor of behavioural medicine at the University of Oxford, said: “These cases are worrying and need investigating but advice from all official bodies in the UK is that it is always preferable to vape than to smoke. These reports should not change that advice.”