A traveller should never venture far without his personal bottle of Hydrogen Peroxide and his trusty Alum stone. I took neither, to a place of insanely high heat and humidity, and suffered the indignity of smelling like a stale baby’s nappy from constant, leaking perspiration, and then having to suffer the ritual outbreak of tingling pustules on my lower lip that turned over a number of days into a crusty, pizzalike protrusion that bled every time I opened my mouth.

I thought I had the answer to the cold sores, though. I had been reliably informed that repeated applications