Hydrastis tincture works good. Or Léo Désilets' s Resisthe tincture (my usual), it contains Hydrastis, echinacea and 6 other plants. I haven't had a cold in ages it helps. Other things that will help:
Green tea
Ginseng
Ginger
Mint
*Do consult a doctor BEFORE taking ANY plant products, they may have interactions, side effects and like any meds may not be suitable for everyone.