Ancient Egyptian pharaohs wore kohl eyeliner made from lead-based minerals to shield their eyes from the sun's glare and prevent infections.

Ancient Egyptian kohl was far more than a cosmetic choice—it was a sophisticated pharmaceutical innovation used as early as 4000 BCE. Groundbreaking research published in Analytical Chemistry by scientists from the Louvre Museum and the CNRS revealed that authentic kohl contained two synthetic lead salts: laurionite and phosgenite. These compounds do not occur naturally and required complex chemical synthesis, a process that took weeks to complete.When these lead salts contacted the skin, they stimulated nitric oxide production. Nitric oxide is a crucial signaling molecule that strengthens the immune response by increasing blood flow and activating white blood cells. This was vital for Egyptians living near the Nile, where stagnant water bred frequent bacterial eye infections such as conjunctivitis. The kohl functioned as a continuous, low-dose antibacterial treatment.Beyond its medicinal benefits, the dark color of galena (lead sulfide) served a physical protective function. Similar to the eye black worn by modern athletes, the dark pigment absorbed incoming solar radiation rather than reflecting it into the eye, dramatically reducing the intense glare of the desert sun. By merging mineralogy and chemistry, the ancient Egyptians created a multifunctional product that safeguarded both vision and health for thousands of years.