You feel groggy because anesthesia does not stop all at once, and your brain and body need time to wake back up. After general anesthesia, you are often drowsy in recovery, may not remember the first few minutes, and can have sleepy thinking, slow reflexes, or poor judgment for hours. Some people also feel sick, shivery, confused, or have a sore throat from the breathing tube. These effects usually get better within minutes to hours, but some recovery effects can last longer, and you should avoid driving and other risky tasks for at least 24 hours after general anesthesia.

The “hungover” feeling can come from the anesthesia itself, pain medicines, or the surgery. Common side effects listed by the sources include drowsiness, nausea or vomiting, chills or shivering, sore throat, muscle aches, itching, and confusion or memory loss. Recovery staff monitor your breathing, heart rate, blood pressure, and temperature, and they can give medicine for pain or sickness if needed. Verify the exact plan with your surgical or anesthesia team in case they want something different for you.