This really does work!
Cold viruses transmit themselves mostly when you pick them up on your hands and then rub your eyes or pick your nose, giving them a direct route to the nasal lining where they multiply in the warm damp conditions. This is why you should always wash your hands first thing on getting into your house especially from shopping and public transport.
I've tried this three times now and it really works: as soon as you get that heady dizzy feeling, sore throat and mild fever and you start sneezing, you need to take urgent action to prevent the virus from multiplying.
First get a bottle of Corsodyl mouthwash. It's expensive in Boots, cheaper in supermarkets and even cheaper in places like Bodycare Toiletries. Gargle with this four times a day, covering your mouth with a tissue because it's very bubbly. At the same time get a small bottle of Vicks First Defence or the Boots own equivalent. This is a solution of saline with carrageenan gel to make it gooey. It works by mimicking the body's own defence: snot. Follow the instructions and spray it up each nostril, it isn't too bad and what it does is to trap the viruses in a hostile gooey solution and carry them away down your throat where you swallow them and your stomach acid deals with them. I also take zinc tablets because there is evidence that zinc reinforces the ability of the nasal mucosa to resist infection. Don't bother with vitamin C, this particular fallacy has grown up because researchers discovered that your ability to absorb vitamin C is reduced when you have a cold; there's no medical evidence that taking it helps stave off a viral infection.
Keep gargling and squirting and stay warm. I also think a good sweat in a hot bath raises the body's temperature and helps kill off viruses but I may be wrong on that one.