Public Health England (PHE) has spoken out amid calls for vaping to be banned following six deaths in the US.
Reports of the vaping-related deaths prompted some calls for e-cigarettes to be banned.
But PHE responded on Twitter by saying despite the risks, vaping is safer than tobacco and more effective in helping people quit than willpower alone.
The agency said: "Our advice on e-cigarettes remains unchanged - vaping isn't completely risk-free but is far less harmful than smoking tobacco.
"There is no situation where it would be better for your health to continue smoking rather than switching completely to vaping.
"All UK e-cigarette products are tightly regulated for quality and safety by @MHRAgovuk. It's important to use UK-regulated e-liquids and never risk vaping home-made or illicit e-liquids or adding substances, any of which could be harmful.
"Smoking kills thousands every year and creating a smoke-free generation is one of our top priorities. Vaping is a fraction of the risk of smoking and makes it much more likely you'll quit successfully than relying on willpower alone.
"The sooner you stop smoking completely the better."
Several deaths in the US were attributed to a "mystery lung disease" that doctors think may be linked to vaping.
President Donald Trump said he will back a federal ban on thousands of e-cigarette flavours.
But the head of Tobacco Control, Martin Dockrell, said there is a clear distinction between vaping in the US and the UK.
He told The Guardian: "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."
