The front of the medal shows a Swiss soldier wearing the M1918 helmet, which was introduced in 1918 and was unique to the Swiss army. Before that, Swiss soldiers wore a 'kepi' type soft cap. Incidentally, this is said to be one of the longest-running helmet designs in modern history, as it continued in use until the early 1970s (with only minor changes to the liner etc.)!
On the back is an inscription in French, German and Italian, superimposed over a Swiss national cross. The inscription states: "Swiss national donation for our soldiers and their families."
Image at left (1919 newspaper article) courtesy of Christian Schülé.
Above is a poster appealing for funds for the 'Don National'. Source: University of Montreal.
Now another example of the medal image, this time on a cigarette case: