Neostigmine is water-soluble, an ionized compound that reversibly inhibits the enzyme acetylcholinesterase. Its FDA indication is for the reversal of the effects of non-depolarizing neuromuscular blocking agents after surgery. The use of neostigmine is primarily found in the context of the reversal of neuromuscular blockade during the administration of anesthesia to patients undergoing surgery that require muscle relaxation. This activity outlines the indications, mechanism of action, methods of administration, important adverse effects, contraindications, monitoring, and toxicity of neostigmine so that providers can direct patient therapy to optimal outcomes in anesthesia reversal.