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What are the Most Common General Anesthesia Side Effects?

Timber Shelton
Timber Shelton

General anesthesia is used for most major surgeries and has a very low rate of serious side effects. It does carry more risks than local or regional anesthesia, but the side effects are generally minor and pass quickly. A person who has been given general anesthesia may experience headache, nausea and tiredness, but these issues are generally temporary. Only rarely do serious issues like allergic reactions, breathing problems or strokes occur.

Temporary Side Effects

A headache can be a side effect of general anesthesia.
A headache can be a side effect of general anesthesia.

Some of the potential general anesthesia side effects are due to mechanical damage to the body from the breathing tube that the anesthetist may place down the throat and into the airway to help the patient breathe while unconscious. The insertion and removal of the tube can cause injury or irritation to the throat and larynx, and often leaves the throat feeling very sore and dry. Hoarseness, coughing, and muscle spasms in the voice box or bronchial tubes in the lungs can all occur, but are uncommon. In rare cases, the teeth or other parts of the mouth and throat may be damaged when the equipment is inserted; a loose tooth could be knocked out, for example.

A patient being given general anesthesia by gas.
A patient being given general anesthesia by gas.

An increase in blood pressure and heart rate also are common general anesthesia side effects, but don't normally cause lasting complications. There may be bruising where an intravenous (IV) line was inserted along with muscle pain. Many people are tired and confused when they wake up, which may lead to coordination problems or even aggression if the person doesn't know where he or she is; these usually pass within 10 or 15 minutes, although a general feeling of tiredness can last longer.

Tiredness may develop after surgery involving general anesthesia.
Tiredness may develop after surgery involving general anesthesia.

Among the most common issues after a patient wakes up from a general anesthetic are headaches, feeling nauseous and vomiting. Patients are usually asked to fast before surgery, which leaves the stomach empty and makes vomiting less likely. A medical professional can also provide anti-nausea medication.

Shivering or trembling also is a very common side effect that occurs in about 40% of patients. This is partly due to the heat loss that usually occurs in cold operating rooms, but also can be a direct result of the anesthesia — the body's temperature thermostat resets while under general anesthesia, allowing it to tolerate the colder temperatures. When a patient wakes up, the body's thermostat returns to normal and may react to a lingering low body temperature by shivering.

Serious Side Effects

An increased heart rate is one sign a patient under anesthesia may be rousing.
An increased heart rate is one sign a patient under anesthesia may be rousing.

Serious general anesthesia side effects and complications during surgery are rare, but possible. Allergic reactions, infections, and lung problems can potentially occur. Heart problems and stroke are unlikely, but are also potential risks, and a condition called malignant hyperthermia, where a patient develops a dangerously high fever, is also a possibility. Waking up during surgery, called anesthesia awareness, is also known to happen, but only occurs in about 1 in 14,000 cases. The chance of dying after receiving general anesthesia is about 1 in 250,000, though this is rarely due to the anesthesia alone.

Vomiting may be a side effect of general anesthesia.
Vomiting may be a side effect of general anesthesia.

During the surgery, the anesthesiologist will pay careful attention to the patient's breathing, heart rate, and other vital signs. Anesthesiologists are trained to look for allergic reactions and other serious general anesthesia side effects, and they can react quickly to treat any that develop.

Though very rare, some serious side effects of general anesthesia can occur within a time span of two weeks after surgery. Some patients may experience pale or yellow skin or eyes, or unexplained body pain. Severe headache, nausea, or weakness may also occur. Black or bloody vomit or stool or unexplained weight loss are also indicators of a serious reaction. Anyone who experiences one or more of these side effects after undergoing general anesthesia should a visit a medical professional or the emergency room.

Risk Factors

Many factors, including a patient’s age and current health, play a part in how he or she will respond to general anesthesia. Heart, lung, circulatory, and nervous disorders may increase the risk of problems. Medical history, drug or food allergies, and previous reactions to anesthesia are important risk factors that the patient should talk about with the surgeon or anesthesiologist. In some cases, there may be less dangerous forms of anesthesia that can be used on people who are at a high risk.

Patients should also tell the surgeon and anesthesiologist which prescription medications, herbal supplements, or over-the-counter drugs they are taking. The use of alcohol, tobacco, or illegal substances can also affect the risks of anesthesia, so these should also be discussed prior to the operation taking place. People who use opiates or cocaine may be more likely to experience anesthesia awareness, for example.

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Discussion Comments


I know someone who had teeth extracted under general anesthesia about two weeks ago. Everything went well, but since then she keeps having these panic attacks to the point she can no longer drive. The hospital could not find anything unusual. She doesn't feel like she's stressed about anything and no longer drinks soda or anything with caffeine. She is only on medication for high blood pressure and that is controlled. What could be the cause of these attacks?


Does the removal of wisdom teeth hurt?


I had two of my bottom wisdom teeth out three days ago. It was done under local anesthesia. It was supposed to last only two hours, however, the right side of my bottom lips is still numb. Is this normal?


@anon303922: For dental surgery, you won't be out that long, and you'll probably be in recovery for a little while. How loopy you are depends on how you react to anesthesia. Everyone is different. You will want someone to drive you home.

Make sure you follow your doctor's post-operative care instructions to the letter. Mine were: get my meds filled, go home, take some pain meds with something sweet and carbonated, and go to bed. You probably won't feel like much of anything the rest of the day. Mostly, you'll just feel really sleepy. Go with that. Sleep when you need to. It can take a while for the body to completely get rid of that stuff.


Do you go all loopy or lost afterwards? I am going to have four teeth removed.


@anon279480: It is probably normal. Anytime you have dental surgery, you tend to swallow some blood. This can make stool dark. Happened to me when I had my wisdom teeth out.


My boyfriend had some teeth pulled and it has been roughly two days. Since then after being put to sleep he has had black stool. Is this normal?


My sister just underwent an appendectomy last sunday. Three days after, she still cannot stand for five minutes because, she will be nauseated and will experience severe headache. Up to now she was just lying still. We are worried.


after general anesthesia, my patient was unable to swallow. what could have happened, when can he start swallowing again?


Can you tell me some more about cardiac anesthesia? My father in law is going in for heart surgery in a month or two, and we're trying to learn all we can about what he's going to be going through.

I would also like to know more about the anesthesia complications that can happen during a cardiac surgery, just to be prepared for the worst.

He's pretty old, and has had a bad heart for some time now, so we're all pretty worried about him. Any information you have would be extremely helpful.



@earlyforest -- There are actually a lot of things you can do to help tone down side effects from general anesthesia both before and after your surgery.

First, before you have your surgery your doctor will meet with you to explain the procedure. During this meeting, you should tell him or her about any allergies you have, and any medications you are taking. That way they can be sure to watch out for any unexpected complications during the surgery.

Next, make sure that you don't eat anything for about eight hours before your surgery, and don't drink anything for two hours before your surgery. This will help keep you from throwing up during or after the procedure. It's also a good idea to take an anti-nausea medication before your surgery, as long as your doctor OKs it.

After the surgery, there are a few things you can do as well. You should probably keep some throat lozenges on hand in case of hoarseness or a sore throat, and you can also gargle with saltwater to soothe your throat and help it heal.

If you still feel nauseous, you can ask your doctor if it's OK to take an anti-nausea medication. Also, stick to the BRAT diet, and avoid sugary drinks.

Finally, just give yourself time to heal. The side effects of general anesthesia affect everyone differently, so go with what your body tells you.

Good luck!


Hi -- I'm going in to have an appendectomy next month, and I think that they're going to use a general anesthetic. I was wondering what I could do to minimize some of the side effects after the general anesthesia.

I've read several different articles on the subject, but this was really the clearest one that I saw, so I was wondering if you could give me some advice.

I'm not really sure what kind of anesthesia machine they're going to be using or anything, so I can't help you there, but if you could just give me some general tips I'd really appreciate it.


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    • A headache can be a side effect of general anesthesia.
      By: Subbotina Anna
      A headache can be a side effect of general anesthesia.
    • A patient being given general anesthesia by gas.
      By: reflektastudios
      A patient being given general anesthesia by gas.
    • Tiredness may develop after surgery involving general anesthesia.
      By: Karin & Uwe Annas
      Tiredness may develop after surgery involving general anesthesia.
    • An increased heart rate is one sign a patient under anesthesia may be rousing.
      By: beerkoff
      An increased heart rate is one sign a patient under anesthesia may be rousing.
    • Vomiting may be a side effect of general anesthesia.
      By: Tom Wang
      Vomiting may be a side effect of general anesthesia.