Aspartame has been accused of 105 side effects (alright sort of an exaggeration but not quite) however I have only had a doctor, Dr. Eugene Smith of Sydney Nova Scotia, confirm one of them: Heart Palpitations in weakened circulatory systems. Fetal, renal, pulmonary side effects have been claimed but never substantiated. All in all, most artificial sweeteners are defined as bad because of a panicked crusade started in the 80's against almost all chemical sounding food additives, aspartame and monosodium glutamate getting the worst of it.