I have been used 50 mg zinc for improving common cold symptoms. Search pubmed for "cold symptoms zinc" and you will see many studies. Zinc supplementation is beneficial for MS, too. Before taking it, ask your doctor, so that you have a professional opinion, but AFAIK it is completely safe. Stay away from echinacea because it could be detrimental when used by MSers.
Shortest joke: "We may not be able to cure MS but we can manage its symptoms."