First Defense is completely safe and non-toxic for infants and children of all ages and may be used to support the immune system at the first sign of any acute symptom, e.g. cold, cough, flu, fever, sinusitis, sore throat or ear infection. It is also recommended for use at the first sign of any susceptibility to infection, e.g. increase in nasal mucus, changes in mood or energy level, as well as periodically to increase natural defense responses. A homeopathic Formula.