Suncreme and Lipsalve
Suncream needs to be at least factor 30 as UV exposure on the high glaciers is really vicious; bring two small tubes rather than one big one so it's easier to carry. Total sunblock face whitening zinc oxide cream is as effective as it is unstylish.
An anti-sun lipstick is essential as lips are particularly vulnerable; it can also be used to top up sensitive areas like the tops of ears and under the nose.
Quantity: 1 or 2 of each