Massive or chronic Levothyroxine intoxication will result to thyrotoxicosis that may lead to cardiac arrhythmia, heart failure and coma. In acute over dosage, gastric lavage, induction of emesis, or administration of activated charcoal may be initiated to reduce gastrointestinal absorption of Levothyroxine. Symptomatic and supportive treatment is given along with hospitalization during Levothyroxine intoxication. Symptomatic treatment for sympathetic over activity includes the administration of Propranolol. It is highly recommended to have extended follow-up check up on Levothyroxine intoxication since symptoms of toxicity may be delayed. This is due to gradual peripheral conversion of T4 to its active form T3.