I swear by black elderberry extract. If it were only placebo effect I don't know why nothing I tried before that ever worked for me. I pretty much have to get on it as soon as I start feeling a little run down like I'm going to catch something, and if I do, either I won't catch the cold at all, or I'll get well super fast.
But +1 on the allergens. I treat all of mine year round. It takes months to build up to a full dosage, so there's really no point in going off shots once the season is over (never mind there's something I'm allergic to in every season anyhow ).
Everything I know, I learned by crashing.
2007 Cannondale Synapse Feminine 3 - SI Turbomatic Gel Flow
2003 Trek Navigator 200 - Specialized Jett 155