The active ingredient in the tanning solutions we use, Vani-T, is dihydroxyacetone (DHA). Whilst DHA may sound like a dangerous chemical concoction, it is in fact a colourless sugar. DHA causes a chemical reaction with the amino acids of the outer most layer of the skin and it is this reaction that causes the colour of the skin to change, producing a beautiful natural tan. DHA starts to react with the skin within 1 hour of the tan application and continues to do so for several more hours, causing a darker reaction the longer it is left to react with the skin.