By supplying the nicotine that smokers are addicted to without the harmful components of tobacco smoke, e-cigarettes can prevent most of the harm from smoking and are likely to be beneficial to UK public health, the RCP's study concluded.
Smokers should be "reassured and encouraged" to use them, while the public can be reassured that e-cigarettes are much safer than smoking.
In addition, while the RCP acknowledged the need for "proportionate regulation", it also suggested that regulation should not be allowed to "significantly [inhibit] the development and use of harm-reduction products by smokers". Regulatory strategies should both ensure product safety and encourage smokers to use the product instead of tobacco.
"The growing use of electronic cigarettes as a substitute for tobacco smoking has been a topic of great controversy, with much speculation over their potential risks and benefits," Professor John Britton, chair of the RCP’s Tobacco Advisory Group, said.
"This report lays to rest almost all of the concerns over these products, and concludes that, with sensible regulation, electronic cigarettes have the potential to make a major contribution towards preventing the premature death, disease and social inequalities in health that smoking currently causes in the UK. Smokers should be reassured that these products can help them quit all tobacco use forever."
Last year, a study by Public Health England found e-cigarettes were 95 per cent less harmful than traditional cigarettes.
The RCP's new, comprehensive 200-page report has examined the science, public policy, regulation and ethics surrounding e-cigarettes and non-tobacco sources of nicotine, addressing some of the key controversies around vaping since e-cigarettes were first introduced in 2007.
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As well as concluding that e-cigarettes are not a gateway to smoking, the study also found there is no evidence that e-cigarettes result in the normalisation of smoking. It also found e-cigarette use is likely to lead to successfully quitting tobacco smoking that would not otherwise have happened.
Tobacco smoking remains that biggest avoidable cause of death, disability and social inequality in the UK, which has around 8.7m smokers, or 18 per cent of the population.
Half of all lifelong smokers die early, losing an average of three months of life expectancy for every year smoked after the age of 35.
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The RCP acknowledged that the possibility of some long-term harm from e-cigarette use cannot be dismissed, but said it is likely to be "very small, and substantially smaller than that arising from tobacco smoking".
With "appropriate product standards" that minimise exposure to other ingredients, it should be possible to reduce health risks even further.
Ram Moorthy, deputy chair of the board science at the British Medical Association, said: "This report provides much needed insight and evidence which will help inform the debate on e-cigarettes. It is certainly interesting to see the RCP assessment of tobacco harm reduction, which recognises the potential for e-cigarettes to reduce harm associated with tobacco use.
"E-cigarettes are increasingly being used by current and ex-smokers to help cut down and quit smoking, so regulation should focus on making sure that these devices are safe and effective for those wanting to stop smoking, and ensuring their marketing does not appeal to children and young people.
"Doctors want to see strong regulation of e-cigarettes. Regulating e-cigarettes as a licensed medicinal product best reflects their use for harm reduction and ensures their effectiveness, quality, and safety."