The document discusses three natural remedies for the common cold: Echinacea, vitamin C, and zinc. Echinacea is an herb that may enhance immune function and has antiviral properties, but research on its effectiveness is mixed. Vitamin C supports the immune system and may slightly reduce cold symptoms duration and severity. Zinc also supports the immune system and may have antiviral effects, but can cause side effects when taken orally. All three remedies have potential side effects like rashes, nausea, and copper deficiency.