In addition to DHA (derived from beet root), the Tropic Sun Drops Gradual Tanning Facial Serum (£22) also contains something called plant allo-melanin, which is a particularly clever ingredient that mimics the colour of your own melanin (the pigment that determines skin and hair colour) to create a more subtle, natural-looking tan. It also contains antioxidant-rich passion fruit extract, to brighten up dull skin, and coconut water, which has electrolytes and amino acids to instantly hydrate. The result? A gentle, highly nourishing facial serum that creates a subtle golden tan. "Finally a facial tanner that does't cause spots or irritate my sensitive skin!" one reviewer on the site said of the formula.