Children from the age of four onwards can take Optibac Probiotics For Those On Antibiotics. The strains in this supplement have not been tested on infants and babies so we cannot recommend that under fours take it. Younger children who need to take antibiotics can be given our Babies & Children supplement, which is suitable for all ages from birth onwards. This supplement contains the renowned Lactobacillus rhamnosus GG strain which has been widely researched in children taking antibiotics(5,6). For children of all ages, once their course of antibiotics has been completed we recommend they take one of our children's products for at least a couple of months to complement the gut microbiome.