The most important thing about this 'cure' is that you start the treatment immediately when you feel like getting a cold, slightly coarce throat etc.
I recommend canarian honey rum for this cure. Pour one shot or swig it straight from the bottle, hold it in your mouth and gargle in your throat. You must do this atleast twice a day, preferably in the morning and in the evening. Between these two shots you must keep drinking drinks such as home made red/black currant juice mixed with sugar and hot water. Hot chocolate will also suffice or honey mixed with hot water. As a bonus you can mix rum in hot chocolate if you're not working that day

Repeat this for atleast 2 days, 3 days to be safe. This may kill your cold altogether but if not it will atleast tame it down so much you will hardly notice you have a cold. (Thank you Tiare for reminding me to post this).