Learn about the side effects of lidocaine, from common to rare, for consumers and healthcare professionals. Toxicity from local anesthetics, including lidocaine, is clinically termed Local Anesthetic Systemic Toxicity (LAST). It is a rare but potentially life-threatening condition, affecting the central nervous system (CNS) and the cardiovascular system. Understanding potential adverse reactions, such as lidocaine toxicity, is important for patient well-being. This article explains what lidocaine toxicity involves, its causes, how to recognize its signs, and its management and prevention. Local anesthetic systemic toxicity (LAST) is a rare complication that can develop within minutes of receiving local anesthetics. It’s a medical emergency that causes nervous system and heart issues. This article talks about how lidocaine overdose happens, the signs and symptoms of lidocaine toxicity, and what to do if you think you've received or taken too much lidocaine. This topic will discuss the pathologic pharmacology, mechanisms, and clinical presentation of toxicity, predisposing factors, and prevention and management of LAST. Lidocaine is a local anesthetic and generally safe. However, it is possible to develop direct nerve and systemic toxicity with too much lidocaine. For more acute poisoning with a shorter anticipated duration (e.g., local anesthetic systemic toxicity), higher doses may be reasonable for a shorter period (e.g., 500-1,000 ml infused over 30-60 minutes). Lidocaine toxicity is not only determined by the total dose (usually 4.5 mg/kg) but also by the rate of absorption, which is dependent on the blood flow of that tissue. We present a rare case of lidocaine-induced systemic toxicity in a healthy 33-year-old female who underwent an elective procedure as an outpatient. Our aim is to raise awareness among general internists to identify the warning signs of local anesthetic toxicity.