The star ingredient in the new Murad Rapid Dark Spot Correcting Serum (£75) is tranexamic acid, which helps inhibit the production of tyrosinase in the skin — the enzyme that allows the overproduction of melanin in the first place, leading to dark spots and hyperpigmentation. We spoke to Dr Amelie Seghers, consultant dermatologist at London's Cadogan Clinic, a while back about tranexamic acid for a story on skin-care acids and learned that "tranexamic acid is a drug originally designed to reduce blood loss and is on the World Health Organisation (WHO) list of essential drugs precisely for this reason. Over time, it became clear that it has additional benefits such as improving the pigmentation seen in melasma," she explained. "It works by disrupting the the formation of melanin and the way it is transferred to skin cells and has excellent qualities in improving the appearance of postinflammatory hyperpigmentation and melasma with fewer side effects compared to hydroquinone."