Possible Complications of Anesthesia

Anesthesia is generally safe, but complications can occur. Local anesthesia carries the lowest risk, and general anesthesia the highest. An allergic reaction to an anesthetic agent can be life threatening and can occur with any type of anesthesia. Drug allergies remain unknown until the substance is ingested, so many people are unaware of them.

There are generally few adverse reactions to local anesthesia. Some patients experience nausea and vomiting, but that is usually caused by the sedative. There may also be soreness at the injection site.

Regional anesthesia has a higher risk of side effects and complications, including the following:

  • Temporary weakness or paralysis of the affected area
  • Headache following spinal and epidural anesthesia. This usually begins within 12 to 24 hours after surgery and can last a week or longer. It may be caused by a loss of spinal fluid that occurs when the anesthetic is injected. Headache is often accompanied by nausea, vomiting, dizziness, light sensitivity, and a stiff neck.
  • Hypotension (low blood pressure)
  • Inability to urinate (usually temporary and relieved by catherization)
  • Backache

Much less frequently, infection, nerve damage, or permanent paralysis can occur.

Because it affects the entire body, general anesthesia has the potential to cause the greatest number of side effects and complications. Most side effects clear up within 24 hours or so. The most common ones are:

  • Sore throat (caused by the devices used to keep the airway open)
  • Drowsiness or feeling tired hours after surgery
  • Nausea and vomiting
  • Headache, dizziness, and vision problems
  • Damage to teeth (caused by airway devices)

General anesthesia also carries the risk for serious complications. The patient's risk depends on several factors including age, sex, allergies, overall health, underlying medical conditions, and current use of tobacco, alcohol, and drugs. Serious complications include the following:

  • Stroke
  • Heart attack
  • Brain damage
  • Death

In August 2012, results of a study published in Pediatrics indicated that anesthesia before the age of 3 may increase the risk for deficits in language and abstract reasoning. Researchers stress that parents should not delay necessary surgery because of these findings, but they should talk with their child's doctors about any concerns.

Certain inhaled anesthetics can trigger a disorder called malignant hyperthermia in people who carry the gene for it. When exposed to these anesthetic agents, the metabolism speeds up, the muscles become rigid, and body temperature rises (may even exceed 110ยบ F). If this disorder is known to run in the family, the patient must inform the anesthesiologist before surgery.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 01 Nov 2001

Last Modified: 21 Aug 2012