The difference between anesthesia and analgesia lies in the effect that the type of drug has on pain levels. Analgesics are drugs that reduce pain but do not remove the sensation of pain altogether, such as the over-the-counter drug acetaminophen. Anesthesia refers to a complete removal of pain, and this is often accomplished by administering a drug that causes a loss in consciousness. Occasions exist in which both anesthesia and analgesia might be utilized, such as during and after surgery. After the anesthesia used during surgery has worn off, the patient might then be given an analgesic to reduce his or her pain during recovery.
Anesthesia and analgesia differ in their mechanism of action as well, with most analgesics being in pill form and most anesthetics entering the body in gas form via inhalation or liquid form via injection. Additionally, analgesics and anesthetics differ in their ability to target parts of the body. An analgesic generally affects the entire body, and anesthetics might be targeted toward a specific anatomical region.
Analgesics are classified into one of two categories: narcotics and non-narcotics. Narcotic analgesics might exist either as an opiates or as opioids. An opioid is a chemical that decreases pain through a complex reaction that involves the binding of multiple receptors that are specific to this chemical, and the term "opiates" describes a narcotic opioid alkaloid or a specific type of opioid. Both of these physiologically depressing substances serve as the base for many modern pain-relieving medications. Within the non-narcotic class of analgesics, acetaminophen is the most commonly used drug to relieve pain.
Anesthetics are classified into local anesthetics, regional anesthetics and general anesthetics. Local anesthetics such as lidocaine target a small area of the body, minimizing nerve activity only to that area while the patient remains conscious. Regional anesthetics block pain to a larger part of the body while the patient remains conscious, and they are injected near major nerves or in the spinal cord. General anesthetics are administered intravenously or inhaled in gaseous form, and affect both the brain and the body, leaving the patient unconscious.
Although anesthesia and analgesia are different, they are not opposing but rather accompanying methods of pain management. Anesthesia is usually accompanied by analgesia; but as previously stated, anesthesia is fundamentally different in that it seeks to remove sensation rather than simply decrease pain levels. Both methods of pain management act on the nervous system, but another differing characteristic of anesthesia and analgesia is that anesthesia is typically more invasive and requires more medical expertise in administration, and analgesics are often independently administered by a patient and might be available without a prescription.