KiddieBoost and Congesto-K Kiddie Spritzer are both good remedies for the immune system and colds/flu. You can also boost his immune system with a good multi-vitamin, lots of vitamin C (maybe via a juice he likes such as orange juice) and making sure he’s getting very healthy meals. Plenty of water is also a must. I would highly encourage you to talk to your son’s doctor if you have any concern over his condition. I am quick to treat myself or my adult children with natural methods, but when a small child is ill, I would always err on the side of caution and seek professional medical advice as well.