Garlic extract works wonders on a cold. Me and my dad buy these little pills that have this, and whenever we get sick we take about 20 a day. Sounds heavy I know, but they're really small and it's only garlic jiuce after all. Every time we do this we're cured within 2-3 days.

Of course I've found 8 grams Vitamin-C (spread out throughout the day) + 400IU Vitamin-E to work even better, usually curing me by the next morning.