Yes disclosing tablets or solutions are safe to use. Plaque disclosing agents use dye and material like food dyes, erythrosine and fluorescein that are not harmful to your health. Keep in mind that disclosing material shouldn’t be swallowed. If your kid is very young (below 6 years of age) and have problems in swishing, you need a pediatrician or a dentist’s help and advise on how to use disclosing solutions and tablets.