Clinical effectiveness of lidocaine lasts between 1 1/2 to two hours depending on the half-life, according to Drugs.com. The half-life of lidocaine can double and last between three and four hours for patients with liver dysfunction.
Despite the half-life of lidocaine being two hours, the drug is extensively metabolized rapidly, thereby increasing the rate of absorption, which can cause death, reports Everyday Health. The difference in length of time lidocaine lasts in the body is also dependent on the water content, body weight as well as liver and renal functions, as revealed by Drugs.com. Renal dysfunction has no effect on the length of time lidocaine lasts in the body, but it speeds up metabolite accumulation.