There isn’t any medicine that can prevent a cold once you’ve got it. A paracetamol based hot drink such as “Lemsip” will make you feel better. There are also sprays which reduce the swelling in your nose and allow you to breath easily. There are many different makes of cold remedy, and it doesn’t matter which one you get, as they all contain the same active ingredients!
Actually I take large doses of Vitamin C when i feel a cold coming on and have only had one bad cold in about 2-3 years. Don’t forget to get lots of rest!
I think the medication you are thinking of is Airborne. It supposedly heads off colds at the first appearance of symptoms.
The efficiency has not been proved because it cannot be proved. In fact, the evidence is in the cure.