Reality: Zinc, vitamin C and Echinacea have all been heralded as natural immune-system boosters. Unfortunately, there’s no good evidence that any of these products can actually ease the symptoms of a cold in adults or kids. Always talk to your child’s doctor before giving your child any supplements or medicines. 

Source: https://www.avera.org/services/wellness-preventive/health-wellness-information/the-truth-about-colds–flu/