Whenever you have surgery, anesthesia helps you get through the procedure without pain. While anesthesia acts mostly during the operation, some effects may persist afterward. The types of after-effects depend primarily on whether you are fully asleep -- as with general anesthesia -- or receive regional or local anesthesia. Nausea, vomiting and sleepiness are among the most common effects after general anesthesia. With all types of anesthesia, most effects resolve within the first 24 hours after surgery.
Temporary Effects After General Anesthesia
General anesthesia can produce a number of effects that occur primarily in the first few hours after awakening. They typically disappear within 24 hours, as anesthesia medications leave the body. If symptoms persist after this, they are usually caused by other factors, such as the use of painkillers or the after-effects of surgery itself. Common temporary effects include nausea, vomiting, sleepiness, dizziness, difficulty urinating and impaired thinking. Difficulty with urination may require insertion of a drainage tube into the bladder. Nausea and vomiting are generally treated with medications.
Short-Term Effects After General Anesthesia
Some effects may persist for a few days after general anesthesia. Mild sore throat and hoarseness are common examples of these short-term effects. Several factors may contribute to these two symptoms, such as pressure from a breathing tube that is often used during general anesthesia, breathing in dry air and anesthesia gases, and being required to avoid eating or drinking for a period of time before surgery. Succinylcholine, an anesthesia muscle relaxant medication, may produce short-term generalized muscle pains.
Confusion -- known as postoperative delirium -- is another possible short-term effect. It is more common in older individuals, especially after major surgery. Anesthesia may play a role in the development of postoperative delirium, but other factors likely contribute as well, including the use of painkillers, the stress of surgery and simply being in the hospital.
Long-Term Effects After General Anesthesia
General anesthesia is very unlikely to cause long-term effects. A possible exception is cognitive impairment lasting beyond the first couple days after surgery, known as postoperative cognitive dysfunction (POCD). It is characterized by decreased ability to remember and think. The impairment is often mild, usually resolves within 3 to 6 months and is more common in older people and after major surgery. Although anesthesia has been suggested as a factor contributing to POCD, its role is uncertain. Authors of a February 2014 review article in "Current Opinion in Anaesthesiology" indicated that the main cause of POCD is brain inflammation caused by the surgery itself.
Effects After Regional Anesthesia
During regional anesthesia, local anesthetic medication is injected at a specific location, producing numbness and muscle weakness in a certain area of the body. In spinal anesthesia, for example, local anesthetic is injected into the fluid around the spinal cord to produce numbness and weakness in the lower part of the body. After surgery, numbness and weakness persist for a period of time that depends on the location of the injection and the type of anesthetic medication. Some forms of regional anesthesia can last up to 24 hours.
Spinal anesthesia may cause difficulty urinating in the first several hours after surgery until bladder sensation returns. It may also produce a headache -- called a postdural puncture headache -- that is present when sitting or standing but disappears when lying down. This headache may persist for several days and can be severe. Sedative medications are often injected through a vein when people receive regional anesthesia during surgery. These medications may cause symptoms similar to, but generally not as severe as, the temporary effects seen after general anesthesia.
Effects After Local Anesthesia
During local anesthesia, local anesthetic medication is injected directly into the area of surgery. This type of anesthesia is generally reserved for minor operations in a small area of the body. Numbness produced by the anesthetic may persist for a few hours after surgery. As with regional anesthesia, if sedative medications are used, they may produce mild, temporary effects.
Because of the possibility of temporary sleepiness, dizziness and impaired thinking after general anesthesia, it is generally recommended that people avoid driving, operating machinery, making important decisions or consuming alcohol for the first 24 hours after surgery. These same precautions are also recommended when sedative medications are used with regional or local anesthesia.
When to Seek Medical Attention
Seek medical attention if you have temporary or short-term effects of general anesthesia that are severe or last longer than expected. After regional anesthesia, obtain prompt medical care if you notice the following:
- significant pain at the injection site
- blood or other fluid leaking from the injection site
- numbness or weakness persisting beyond the time expected
for your specific type of anesthesia
- International Anesthesiology Clinics: Cognition, Anesthesia and Surgery
- Anesthesiology Clinics: Peripheral Nerve Blocks for Ambulatory Surgery
- Anesthesiology Clinics: Postoperative Urinary Retention
- Anesthesiology Clinics: Postoperative Issues: Discharge Criteria.
- Current Opinion in Anaesthesiology: Cerebral Protection: Inflammation, Endothelial Dysfunction and Postoperative Cognitive Dysfunction
- Deutsches Arzteblatt International: Postoperative Cognitive Dysfunction
- British Journal of Anesthesia: Postoperative Cognitive Dysfunction and Dementia -- What We Need to Know and Do