Medicines watchdogs have warned the public about the health risks of using unlicensed tanning injections and nasal sprays.
The Medicines and Healthcare products Regulatory Agency (MHRA) issued an alert over products containing the substance melanotan.
These products are being sold over the internet but also in gyms, beauty parlours and tanning salons.
The MHRA said it had received 18 reports of 74 separate reactions suspected to be caused by melanotan since 2008, including stomach and heart problems as well as blood and eye disorders.
The agency has now closed down 72 websites offering melanotan in the last three months and plans to continue monitoring websites targeting UK consumers.
Products called Melanotan I, Melanotan II and Ubertan work by increasing levels of melanin - a pigment which determines skin colour - in the body, leading to a tan.
But none of the products containing melanin have been approved for use in the UK and carry the risk of serious side-effects.
The products can also be injected, carrying an extra risk of infection from needles.
The MHRA issued to warning to alert those sicking a quick pre or post-holiday tan about the potential pitfalls of using the illegal products.
Lynda Scammell, the MHRA’s senior policy advisor for enforcement, said: “People should not be fooled that this is a shortcut to getting a tan safely.
“These tanning products have not been approved for use in the UK and there are no guarantees that they are safe, of an acceptable quality or effective in use.”
Nina Goad, from the British Association of Dermatologists, said: “It is worrying that people seem to be ignoring the warnings about tanning injections.
“There are several reports of people’s health suffering as a result of using such products, which illustrates why people should stick with safer ways of getting a tan, such as self-tanning lotions.
“The very fact that it is illegal for sale in the UK should serve as the strongest warning against injecting a substance into your body for which we don’t yet have the full safety data.”
People who have experienced a side-effect from one of the products can report it via mhra.gov.uk/yellowcard