Sunless tanning (also known as UV-free tanning, self tanning, spray tanning).
Artificial sunscreen absorbs ultraviolet light and prevents it from reaching the skin. It has been reported that sunscreen with a sun protection factor (SPF) of 8 based on the UVB spectrum can decrease vitamin D synthetic capacity by 95 percent, whereas sunscreen with an SPF of 15 can reduce synthetic capacity by 98 percent (Matsuoka et al., 1987).
A safe and effective method of sunless tanning is consumption of certain carotenoids — antioxidants found in some fruits and vegetables such as carrots and tomatoes — which can result in changes to skin color when ingested chronically and/or in high amounts. Carotenoids are natural, and unlike many sunless tanning products, are long-lasting. In addition, carotenoids have been linked to more attractive skin tone than suntan.
Carotenaemia (xanthaemia) is the presence in blood of the yellow pigment carotene from excessive intake of carrots or other vegetables containing the pigment resulting in increased serum carotenoids. It can lead to subsequent yellow-orange discoloration (xanthoderma or carotenoderma) and their subsequent deposition in the outermost layer of skin. Carotenemia and carotenoderma is in itself harmless, and does not require treatment. In primary carotenoderma, when the use of high quantities of carotene is discontinued the skin color will return to normal. It may take up to several months, however, for this to happen.
Carotenoids safe in chronic high doses
Due to its strong color and non-toxicity, lycopene is a useful 
Carotenoids not safe in chronic high doses
A sunless-tanning product is tanning pills which contain beta-carotene.
However, chronic, high doses of synthetic β-carotene supplements have been associated with increased rate of lung cancer among those who smoke. This may be prevented by combining β-carotene with lycopene that is found in lung tissue and is valuable in protecting lymphocytes from NO2 damage found in lung cancer.
Canthaxanthin is most commonly used as a color additive in certain foods. Although the FDA has approved the use of canthaxanthin in food, it does not approve its use as a tanning agent. When used as a color additive, only very small amounts of canthaxanthin are necessary. As a tanning agent, however, much larger quantities are used. After canthaxanthin is consumed, it is deposited throughout the body, including in the layer of fat below the skin, which turns an orange-brown color. These types of tanning pills have been linked to various side effects, including hepatitis and canthaxanthin retinopathy, a condition in which yellow deposits form in the retina of the eye. Other side effects including damage to the digestive system and skin surface have also been noted. The FDA withdrew approval for use of canthaxanthin as a tanning agent, and has issued warnings concerning its use.
The most effective sunless tanning involves the use of lotions and sprays that contain dihydroxyacetone (DHA) as the active ingredient. DHA is not a dye, stain or paint, but causes a chemical reaction with the amino acids in the dead layer on the skin surface. This is similar to the Maillard reaction, a process well known to food chemists that causes the browning that occurs during food manufacturing and storage. It does not involve skin pigmentation nor does it require exposure to ultraviolet light to initiate the color change. The effect is temporary and fades gradually over 3 to 10 days.
These products are available as gels, lotions, mousses, sprays and wipes, some of which also use contact dermatitis.
Professional spraytan applications are available from spas, salons and gymnasiums by both hand-held sprayers and in the form of sunless or UV-Free spray booths.
September 2012 also saw a surge in debate within the United Kingdom regarding the inhalation of DHA through spray tanning. While the quantities inhaled would have to be considerably higher than an average consumer or even spray tan technician would be exposed to, press coverage on the issue has resulted in increased consumer diligence with regard to the level of DHA and other ingredients in their spray tanning products, and a move toward more naturally-derived spray tan solutions. An EU Directive published by the Scientific Committee of Consumer Safety to eventually limit DHA content of spray tan products to 14% has also been cited within this discussion.
DHA has been approved for cosmetic use by the FDA.vitiligo patients.
Although gels, lotions or sprays that contain DHA are said to be the most reliable and useful, there are other types of products on the market. Tanning accelerators—lotions or pills that usually contain the amino acid tyrosine—claim that they stimulate and increase melanin formation, thereby accelerating the tanning process. These are used in conjunction with UV exposure. At this time, there is no scientific data available to support these claims.
Afamelanotide in a subcutaneous implant form is currently undergoing clinical trials and being developed by a company in Australia.
Bronzers are a temporary sunless tanning or bronzing option. These come in powders, sprays, mousse, gels, lotions and moisturizers. Once applied, they create a tan that can easily be removed with soap and water. Like make-up, these products tint or stain a person's skin only until they are washed off.
They are often used for “one-day” only tans, or to complement a DHA-based sunless tan. Many formulations are available, and some have limited sweat or light water resistance. If applied under clothing, or where fabric and skin edges meet, most will create some light but visible rub-off. Dark clothing prevents the rub-off from being noticeable. While these products are much safer than tanning beds, the color produced can sometimes look orangey and splotchy if applied incorrectly.
A recent trend is that of lotions or moisturizers containing a gradual tanning agent. A slight increase in color is usually observable after the first use, but color will continue to darken the more the product is used.
Air brush tanning is a spray on tan performed by a professional. An air brush tan can last five to ten days will fade when the skin is washed. It is used for special occasions or to get a quick dark tan. At-home airbrush tanning kits and aerosol mists are also available.
Most sunless tanning products do not contain 
Risks of inhaling or ingesting DHA are not known. People are advised to close their eyes or protect them with goggles and to hold their breath or wear nose plugs while they have a spray-on tanning applied.
September 2012 saw a surge in debate within the United Kingdom regarding the inhalation of DHA through spray tanning. While the quantities inhaled would have to be considerably higher than an average consumer or even spray tan technician would be exposed to, press coverage on the issue has resulted in increased consumer diligence with regard to the level of DHA and other ingredients in their spray tanning products, and a move toward more naturally-derived spray tan solutions. An EU Directive published by the Scientific Committee of Consumer Safety to eventually limit DHA content of spray tan products to 14% has also been cited within this discussion.
The European Commission Scientific Committee on Consumer Safety has issued a comprehensive 2010 Opinion on DHA in which the committee concluded that DHA and spray tanning did not pose risk to the consumer.
Many self tanners use chemical fragrances which may cause skin allergies or may trigger asthma. Furthermore, some of them contain parabens. Parabens are preservatives that can affect the endocrine system.
Tanners can stain clothes. It is therefore important to look for fast drying formulas and wait around 10 to 15 minutes for the product to dry before dressing.
After self-tanner is applied, the skin may be especially susceptible to free-radical damage from sunlight, according to a 2007 study led by Katinka Jung of the Gematria Test Lab in Berlin. Forty minutes after the researchers treated skin samples with 20% DHA they found that more than 180 percent additional free radicals formed during sun exposure compared with untreated skin.
- Di Mascio (1989) pp. 532–538
- 21 CFR 73.585
- Australia New Zealand Food Standards Code“Standard 1.2.4 – Labelling of ingredients”. http://www.comlaw.gov.au/Details/F2011C00827. Retrieved 2011-10-27.
- UK Food Standards Agency: “Current EU approved additives and their E Numbers”. http://www.food.gov.uk/safereating/chemsafe/additivesbranch/enumberlist. Retrieved 2011-10-27.
- “In Vivo Formation of Maillard Reaction Free Radicals in Mouse Skin”. Journal of Investigative Dermatology. http://www.nature.com/jid/journal/v117/n3/full/5601203a.html. Retrieved 2011-10-24.
- http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=73.1150 Code of Federal Regulations, Title 21, Volume 1, §73.1150 Listing of color additives exempt from certification
- “Induction of skin tanning by subcutaneous administration of a potent synthetic melanotropin”. Vol. 266 No. 19, November 20, 1991. Journal of the American Medical Association. 1991. http://jama.ama-assn.org/cgi/content/abstract/266/19/2730. Retrieved 2008-10-13.
- “WebMd.com – Choosing the Best Sunscreen”. http://www.webmd.com/healthy-beauty/features/whats-best-sunscreen. Retrieved 2010-07-05.
- “Fresh Indulgence – Keeping Your Skin Safe”. http://www.freshindulgence.co.uk/index.php?route=information/news&news_id=30. Retrieved 2012-11-05.
- “How To Address Spray Tan Safety Concerns”. http://www.freshindulgence.co.uk/index.php?route=information/news&news_id=27. Retrieved 2012-11-05.
- “High DHA Percentage Tanning Solutions”. http://www.freshindulgence.co.uk/index.php?route=information/news&news_id=7. Retrieved 2012-11-05.
- “Choose a Natural Self-tanner”. http://www.greenyour.com/body/personal-care/sun-care/tips/choose-a-natural-self-tanner. Retrieved 2010-07-05.
- K Jung, M Seifert, Th Herrling, J Fuchs “UV-generated free radicals (FR) in skin: Their prevention by sunscreens and their induction by self-tanning agents.” Spectrochim Acta A Mol Biomol Spectrosc. 2008 May;69(5):1423-8. Epub 2007 Oct 10. 
This article uses material from the Wikipedia article Sunless Tanning, which is released under the Creative Commons Attribution-Share-Alike License 3.0.