Lidocaine is one of the most commonly used local anesthetics and may also be used in the treatment of arhythmia and serious skin irritation. It is used in both medicine and dentistry. It was developed in 1943 and first marketed in 1949. Its primary benefits as a local anesthetic are its rapid action (initially within seconds with full effect within minutes) and it's intermediate duration, wearing off within a few hours.
It should be avoided in patients with heart block, patients with a history of adverse reaction to the drug, patients with low blood pressure, patients with bradycardia and in patients with a pacemaker.
Lidocaine rarely causes adverse reactions and those are almost always due to improper administration of the drug by the physician. Dosage must be watched as if the drug is allowed to spread through the patient's system (such as what might happen if it is directly injected into a vein in error), the risk of adverse reaction increases.
When used as an anesthetic, lidocaine is usually injected into the skin or muscle. However, for other uses, it is available as a pill, liquid or patch.
Cocaine is occasionally cut with lidocaine because it can fool the user into thinking that the sample is purer as the numbness from lidocaine is actually greater than that from cocaine.