A nasal spray designed to produce a glowing tan is “potentially dangerous”, experts say.

The British Medicines and Healthcare products Regulatory Agency has issued a warning over Ubertan, which is being advertised and sold illegally in UK gyms, beauty salons and online.

Tests carried out on the product have revealed it contains an unlicensed compound called melanotan II, which is similar to a hormone that increases the production of melanin in the skin, causing it to darken.

The MHRA said melanotan II is unlicensed and could have side effects. There is also no evidence proving it is safe or that it works.

Another version of Ubertan tested by the MHRA contained the unlicensed herbal extract forskolin, which has the potential to lower blood pressure and promote secretion of hormones from the thyroid.

Head of the MHRA’s medicines borderline section David Carter said: “Putting your health on the line just in order to get a tan is just really not worth the risk.

“None of these products have been clinically tested and as a result there is no way of knowing just how serious the side-effects could be, or the impact on your health.”