"Nicotine solution" refers to a liquid formulation containing nicotine dissolved in a solvent, typically propylene glycol (PG) or vegetable glycerin (VG). This solution is commonly used in various applications, including pharmaceuticals, nicotine replacement therapy (NRT), e-liquids for electronic cigarettes (vapes), and research. In pharmaceuticals and NRT products, nicotine solution is used to deliver controlled doses of nicotine to individuals seeking to quit smoking. In e-liquids, nicotine solution is an essential ingredient that provides the desired nicotine concentration for vaping. Nicotine solutions may vary in nicotine concentration, allowing users to choose their preferred nicotine strength. Proper handling and storage precautions should be followed when dealing with nicotine solutions due to their toxicity.