When it comes to medical treatment, it's essential to ensure that the correct dosage is given to avoid any harmful consequences. Sometimes, the dosage may be too high, and it is necessary to use synonyms that convey the same message. Some examples of synonyms for "excessive dosage" include "overdose," "unnecessary amount," "unsafe level," "toxic amount" and "lethal dose." It's important to note, however, that these synonyms should be used carefully and only when the dosage is proven to be harmful and dangerous. Therefore, it's crucial to consult with a medical professional to determine the right dosage and avoid any negative effects of medication.