There are several reasons why you shouldn't be taking caffeine pills. For instance, if you are a child under 12 years old, are trying to become pregnant, are pregnant or are breastfeeding, and if you are taking any of the following medications: - Ephedrine - Echinacea - Cimetidine - Ketoprofen - Phenobarbital - Phenytoin We recommend speaking to your doctor if you are taking any medication daily, even if we haven't named it in this article, as we do not qualify to give medical advice.