Anesthesia allows surgery and other medical procedures to proceed while minimizing pain or distress for the patient. While it is generally safe and effective, anesthesia is not without its risks and side effects. Common side effects include nausea, dizziness, and sore throat, which typically resolve on their own. However, clinicians must be aware of uncommon side effects of anesthesia and be able to swiftly implement treatment or supportive measures as needed.
One of the more uncommon but concerning side effects of anesthesia is Postoperative Cognitive Dysfunction (POCD). POCD can manifest as memory loss, confusion, or difficulty concentrating after surgery. The exact cause is not fully understood but may involve a combination of inflammation, stress responses, and reduced oxygen levels to the brain during surgery—while most patients recover fully, it can cause significant temporary challenges in daily life 1–3.
A rare but life-threatening reaction, malignant hyperthermia occurs in individuals with a specific genetic predisposition. Triggered by certain anesthetic agents, malignant hyperthermia leads to a rapid increase in body temperature, muscle rigidity, and severe metabolic disturbances. Immediate treatment with the drug dantrolene and cessation of triggering agents are crucial to prevent fatal complications 4,5.
Anesthesia awareness is a rare and distressing experience in which patients partially awaken during surgery and can feel pain or hear sounds. This typically occurs when the balance between muscle relaxants and sedatives is disrupted. Anesthesia awareness is more likely in emergency surgeries or when lower doses of anesthesia are used due to specific medical conditions. Psychological counseling can help patients cope with any psychological impacts if this occurs 6,7.
Anesthesia, especially regional blocks, can sometimes lead to nerve injury, causing numbness, tingling, or weakness in the affected area. This is usually temporary, but in rare cases, the damage can be long-lasting. Factors contributing to this risk include prolonged surgical positioning, underlying health conditions, and accidental needle trauma during the anesthetic procedure 8,9.
Some individuals may have an allergic reaction to anesthetic drugs or other substances used during surgery, such as latex or antiseptics. Symptoms range from mild skin rashes to severe reactions like anaphylaxis, which can cause breathing difficulties, low blood pressure, and swelling. Preoperative allergy testing can help identify risks in susceptible individuals 10,11.
In rare instances, muscle relaxants used in anesthesia may not wear off as expected, leading to prolonged paralysis. This can be particularly distressing if the patient is conscious but unable to move or communicate; rapid intervention and monitoring can help manage this side effect 12,13.
Finally, postoperative vision loss is an exceptionally rare complication of surgery and anesthesia, most commonly associated with surgeries requiring prolonged face-down positioning, such as spinal surgeries. This is often due to reduced blood flow to the optic nerve and requires urgent medical attention 14,15.
While uncommon, these side effects of anesthesia highlight the importance of comprehensive preoperative evaluations, communication between patients and their healthcare providers, and careful intraoperative monitoring. While patients should remember that severe side effects from anesthesia are rare, clinicians must always be vigilant and prepared to respond in emergencies.
References
1. Rundshagen, I. Postoperative Cognitive Dysfunction. Dtsch Arztebl Int 111, 119–125 (2014). doi: 10.3238/arztebl.2014.0119
2. Brodier, E. A. & Cibelli, M. Postoperative cognitive dysfunction in clinical practice. BJA Educ 21, 75–82 (2021). doi: 10.1016/j.bjae.2020.10.004.
3. Zhao, Q., Wan, H., Pan, H. & Xu, Y. Postoperative cognitive dysfunction—current research progress. Front. Behav. Neurosci. 18, (2024). doi:10.3389/fnbeh.2024.1328790
4. Sinha, A. K., Kumari, P., Vaghela, M. M., Sinha, C. & Kumar, B. Postoperative Malignant Hyperthermia- A Medical Emergency: A Case Report and Review of Literature. J Clin Diagn Res 11, PD01–PD02 (2017). doi: 10.7860/JCDR/2017/20531.9493.
5. Malignant hyperthermia – Symptoms & causes – Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/malignant-hyperthermia/symptoms-causes/syc-20353750.
6. Sandhu, K. & Dash, H. Awareness During Anaesthesia. Indian J Anaesth 53, 148–157 (2009).
7. Anesthesia Awareness. Cleveland Clinic https://my.clevelandclinic.org/health/articles/anesthesia-awareness.
8. Hewson DW, Bedforth NM, Hardman JG. Peripheral nerve injury arising in anaesthesia practice. Anaesthesia (2018). doi: 10.1111/anae.14140.
9. Chui, J., Murkin, J. M., Posner, K. L. & Domino, K. B. Perioperative Peripheral Nerve Injury After General Anesthesia: A Qualitative Systematic Review. Anesth Analg 127, 134–143 (2018). doi: 10.1213/ANE.0000000000003420.
10. Dewachter, P., Mouton-Faivre, C., Emala, C. W. & Riou, B. Anaphylaxis and Anesthesia: Controversies and New Insights. Anesthesiology 111, 1141–1150 (2009). doi: 10.1097/ALN.0b013e3181bbd443
11. Mali, S. Anaphylaxis during the perioperative period. Anesth Essays Res 6, 124–133 (2012). doi: 10.4103/0259-1162.108286.
12. Zaphiratos, V., McKeen, D. M., Macaulay, B. & George, R. B. Persistent paralysis after spinal anesthesia for cesarean delivery. Journal of Clinical Anesthesia 27, 68–72 (2015). doi: 10.1016/j.jclinane.2014.08.003.
13. Syal, K., Sood, A., Bhatt, R. & Gupta, H. Prolonged post spinal anaesthesia paralysis. Indian J Anaesth 59, 376–378 (2015). doi: 10.4103/0019-5049.158757
14. Roth, S. Perioperative visual loss: what do we know, what can we do? Br J Anaesth 103, i31–i40 (2009). doi: 10.1093/bja/aep295.
15. Grover, V. & Jangra, K. Perioperative vision loss: A complication to watch out. J Anaesthesiol Clin Pharmacol 28, 11–16 (2012). doi: 10.4103/0970-9185.92427