Understanding: What are the side effects of anesthesia?

October 10, 2025 •

4 min read

According to the American Society of Anesthesiologists, most side effects of anesthesia are temporary and disappear within 24 hours, but patients and families often have questions and concerns. Understanding what are the side effects of anesthesia is a key part of surgical preparation and can help alleviate patient anxiety. This guide explores the common, rare, and type-specific side effects associated with different anesthetic methods.

Quick Summary

Anesthesia side effects range from common temporary issues like nausea, fatigue, and sore throat to rare, more serious complications. The type of anesthesia significantly influences the potential effects, with general anesthesia having broader systemic impacts and local anesthesia causing milder, localized issues.

Key Points

Anesthesia Type Matters: The side effects you experience depend significantly on whether you receive general, regional, or local anesthesia, with general having the most widespread effects.
Common Side Effects are Temporary: Post-surgery issues like nausea, fatigue, and a sore throat are very common but usually resolve within 24 hours to a few days.
Older Adults Face Higher Risks: Elderly patients are more susceptible to prolonged cognitive side effects, such as postoperative delirium or dysfunction, especially after major surgery.
Serious Complications are Rare: Major complications like anesthesia awareness or malignant hyperthermia are extremely uncommon due to modern monitoring and screening techniques.
Communication is Key: Disclosing your full medical history, medications, and any past anesthetic issues to your care team is vital for a safe anesthetic plan and recovery.
Recovery is Managed: Your anesthesia care team can actively manage and treat common side effects, like nausea and pain, during your recovery period.

Anesthesia is a medical intervention designed to block pain and sensation during surgery or medical procedures. While modern anesthesia is remarkably safe, it is not without potential side effects. These effects can vary significantly depending on the type of anesthesia used, the procedure's duration, and a patient's overall health.

General anesthesia side effects

General anesthesia places a patient in a state of controlled unconsciousness, and the side effects are often more extensive than with other types. As the effects of the medication wear off, common side effects include:

Postoperative Nausea and Vomiting (PONV): A very common occurrence, affecting up to 30% of the general population under general anesthesia and up to 80% of high-risk patients. PONV can be caused by the anesthetic drugs themselves, the opioids used for pain control, or motion during transport.
Sore Throat and Hoarseness: A breathing tube is often used during general anesthesia to ensure the patient receives adequate oxygen. This can cause minor throat irritation, which usually resolves within a few days.
Shivering and Chills: It is common for a patient's body temperature to drop slightly during surgery. Feeling cold and shivering upon waking up is a normal response as the body rewarms.
Drowsiness and Fatigue: It can take some time for the anesthetic drugs to fully clear the system. Patients often feel groggy and tired for several hours or even a couple of days after the procedure.
Muscle Aches: The muscle relaxant drugs used during general anesthesia, along with lying in one position for an extended period, can cause muscle soreness.
Temporary Confusion or Memory Problems: Patients, especially older adults, may experience temporary confusion, disorientation, or have trouble remembering things for a few hours after surgery. This is known as postoperative delirium.

Rare and serious complications of general anesthesia

While highly uncommon, more serious complications can occur:

Anesthesia Awareness: This is the rare event of a patient becoming conscious during surgery while under general anesthesia. It occurs in only 1 or 2 out of every 1,000 procedures and is often due to insufficient anesthetic dosage, particularly in high-risk surgeries like trauma or heart procedures.
Malignant Hyperthermia (MH): A potentially fatal, inherited reaction to certain anesthetic drugs, causing a rapid increase in body temperature and severe muscle contractions. Anesthesiologists screen for a personal or family history of MH to avoid triggering drugs.
Postoperative Cognitive Dysfunction (POCD): A more lasting cognitive impairment involving memory and learning difficulties, which can persist for weeks or months, primarily affecting older patients after major surgery.
Nerve Damage: Rare nerve injuries can result from improper patient positioning during a lengthy surgery.

Side effects of regional and local anesthesia

Regional and local anesthesia numb only a specific part of the body, leading to fewer and less severe side effects than general anesthesia.

Local Anesthesia: With a simple injection to numb a small area, side effects are usually limited to temporary stinging, bruising, or soreness at the injection site. Rarely, local anesthetic systemic toxicity (LAST) can occur, especially in infants under 6 months.
Regional Anesthesia (e.g., epidural, spinal block): This involves injecting anesthetic near a cluster of nerves. Side effects may include:
- Back Pain or Bruising: Minor soreness at the injection site is common.
- Post-dural Puncture Headache (PDPH): A severe headache can sometimes occur if spinal fluid leaks from the injection site. It is more common after spinal blocks.
- Difficulty Urinating: Temporary difficulty emptying the bladder can occur after a block that numbs the lower body.
- Temporary Weakness or Numbness: The intended effect of the block can linger slightly longer than the medication, causing temporary weakness or numbness in the arms or legs.

Managing anesthesia side effects

Most common side effects resolve on their own within hours or days, but there are management strategies to aid recovery. The American Society of Anesthesiologists provides detailed patient information on recovery, available through its "Made for This Moment" initiative, emphasizing that communication with your care team is key for managing any persistent symptoms.

Best practices for a smoother recovery:

For Nausea: Anti-nausea medications are often administered preemptively for high-risk patients. Slowly reintroducing liquids and mild foods after surgery can also help.
For Sore Throat: Drinking plenty of fluids, gargling with salt water, or using medicated throat lozenges can provide relief.
For Confusion: Having a familiar face present and a calm, quiet recovery environment can help orient a patient experiencing postoperative delirium.
For Fatigue: Rest is crucial. Avoid strenuous activities and major decisions for at least 24 hours after surgery involving general anesthesia.

Comparison of anesthesia types and side effects


Feature	General Anesthesia	Regional Anesthesia	Local Anesthesia
Effect	Puts entire body to sleep and unconscious.	Blocks pain in a specific, large region of the body.	Numb a small, specific area of the body.
Common Side Effects	Nausea, fatigue, sore throat, shivering, confusion, muscle aches.	Back pain, headache, temporary weakness, bruising.	Stinging, bruising, or soreness at injection site.
Rare Complications	Anesthesia awareness, malignant hyperthermia, nerve damage, POCD.	Nerve damage, epidural hematoma, infection.	Systemic toxicity (LAST), seizures.
Recovery	Slower return to normal function, potential for lasting effects.	Faster recovery time, localized effects wear off.	Minimal to no recovery time beyond procedure.

Conclusion

Anesthesia plays a critical role in modern medicine, enabling complex and life-saving procedures. While side effects, ranging from minor and temporary issues to rare, serious complications, are a possibility, they are generally well-managed by modern anesthesia protocols and monitoring. A patient's experience is heavily influenced by the type of anesthesia they receive. Communicating your health history and any concerns with your anesthesiologist is the most effective way to minimize risks and manage the effects of anesthesia. By preparing for common effects and understanding the rarity of serious risks, patients can approach surgery with greater confidence.

Frequently Asked Questions

Most common and minor side effects of anesthesia, such as nausea, drowsiness, and a sore throat, typically disappear within 24 hours of the procedure. Effects of general anesthesia can linger for a couple of days, while local effects wear off in a few hours.

Postoperative Nausea and Vomiting (PONV) is one of the most common side effects, affecting about 30% of patients who undergo general anesthesia. Nausea and vomiting can be caused by the medications used and other factors.

Yes, though rarely. The most notable long-term side effect is Postoperative Cognitive Dysfunction (POCD), which can cause memory and concentration problems lasting for weeks or months, particularly in older patients or after major surgery. Permanent nerve damage is a very rare risk.

Yes, temporary confusion or disorientation, known as postoperative delirium, is common, especially in older patients as they emerge from general anesthesia. It usually fades within a few hours or days.

Your anesthesiologist can give you anti-nausea medication before or during your procedure if you are at high risk. Afterward, slowly reintroduce fluids and bland foods and avoid strong smells.

A sore throat after general anesthesia is common due to the breathing tube. You can find relief by drinking plenty of water, using medicated lozenges, or gargling with salt water. Contact your doctor if the soreness persists for more than a week.

You should seek medical attention if you experience severe or persistent nausea and vomiting, chest pain, difficulty breathing, a high fever, severe headaches that won't go away, or any lingering numbness or weakness.