How long does it take for lidocaine to take effect?

　　The onset time of lidocaine varies depending on the route of administration. With local injection, it typically takes effect within 5–15 minutes. When applied topically or administered as a spray, lidocaine acts more rapidly, usually taking effect within 1–3 minutes, quickly blocking nerve conduction to relieve pain or suppress sensation. If adverse reactions such as rash or dizziness occur after use, medical attention should be sought promptly.

　　Local injection is a commonly used clinical method. For example, during dental procedures or minor surgical operations, lidocaine is injected subcutaneously or around nerves. The drug needs to penetrate into the nerve tissue to take effect, resulting in a slightly slower onset; however, its duration of action is longer, typically lasting 1–2 hours, which meets the requirements for most short-duration procedures.

　　Topical application or spraying is primarily used for surface anesthesia of the skin or mucous membranes, such as managing minor skin injuries or relieving pain from oral ulcers. Since the drug acts directly on superficial nerve endings without needing to penetrate deeper tissues, it has a rapid onset. However, its effect is relatively short-lived, usually lasting 15–30 minutes, making it suitable for brief and superficial analgesic needs.

　　It is important to note that lidocaine is a prescription medication and must be used under medical supervision. Avoid purchasing and applying it yourself, especially on broken skin. Store it out of reach of children. Inform your doctor of any history of allergies before using the medication to ensure safe use.