What vitamins is your toddler on?

Hi All, What other vitamins do you give your LO?? My LO just has the daily NHS Healthy Start vitamin drops (contains - Water, Glycerol, Vitamin C, Emulsifier, Polysorbate 80, Vitamin A, Vitamin D and Propylene glycol). But with this cold weather flu season I want to top them up but I always get worried of giving her too much vitamins or mixing them.