Put the elderberries, eucalyptus leaves, apple (including the core), chile and lime juice in a pot and simmer for 15 minutes. Strain through a sieve, pressing with the back of a spoon to extract as much of the pulp as possible.
Skim off any scum, and then bottle in sterilized jam jars, putting a waxed disc, wax-side down, on top. Cover with a round of cellophane and secure with a rubber band or ribbon.
Take 1 generous tablespoon whenever you feel cold symptoms coming on.
The jelly will keep for up to 1 year in a cool dark place. Once opened, store in the refrigerator.