Hello,
There are not really any products or medications to boost the immune system unfortunately. Echinacea is sometimes used to prevent colds, however this product is not really proven effective for this. It is the same thing for probiotics. Given the questionable effectiveness of these products, I would not recommend them.
Unfortunately, frequent colds are a normal part of children's development. It is actually normal for children to have more colds per year than adults.
The best way to prevent these is through hygiene. For example: washing hands frequently, teaching children to sneeze into their elbows, cleaning toys and surfaces frequently, not sharing utensils and glasses, etc.
Also, the only way to truly strengthen a child's immune system is to follow the recommended immunization schedule. In addition, the Canadian Paediatric Society recommends flu vaccination for children.
I hope this answers your questions.
Catherine Deslandes student in pharmacy
Supervised by Alexandre Chagnon pharmacist