Neostigmine is a medication primarily used to treat myasthenia gravis, a condition that causes muscle weakness. It works by inhibiting the enzyme acetylcholinesterase, which breaks down the neurotransmitter acetylcholine. By increasing acetylcholine levels, neostigmine helps improve communication between nerves and muscles, enhancing muscle strength. Additionally, neostigmine is sometimes used to reverse the effects of certain muscle relaxants used during surgery. It can also help with bladder and bowel function in specific medical situations. Common side effects may include nausea, increased salivation, and muscle cramps.