Side effects of general anesthesia


General anesthesia are performed in thousands of clinics every day.

With the help of newer drugs and their special combinations, it is possible to keep the anesthetic risk as low as possible. Nevertheless, every procedure and every general anesthetic is associated with risks, side effects and fear.

Read more on the topic:

  • Risks of anesthesia
  • Fear of anesthesia / general anesthesia

The most common side effects after general anesthesia

Common side effects after general anesthesia are nausea and vomiting after anesthesia. One third of the anesthetized patients experience nausea, 25% vomit. On the one hand, this can be due to medication, on the other hand, the irritation of the windpipe or the nearby nerves.

  • Some patients experience hoarseness a short time after the procedure. This is caused by irritation of the vocal cords from the tube during the operation. In very few cases, the vocal cords are permanently damaged.
  • The so-called aspiration is another complication of general anesthesia. It can happen that gastric juice or water droplets get through the instruments into the lungs and can lead to pneumonia even days after the procedure. The patient's risk of aspiration decreases as the patient becomes sober. If it is an emergency operation before which the patient was not fasted, the risk of aspiration increases rapidly, with life-threatening consequences. In some cases, the medication can cause circulatory instability during and after anesthesia. In this case, the intervention must be shortened accordingly or the monitoring time after the intervention must be extended.
  • A very rare but serious complication of general anesthesia is so-called malignant hyperthermia. This is a genetic disease that breaks out when the anesthetic is given. The metabolic reactions begin to proceed rapidly, the body produces a lot of heat through tremors and the blood salts are unbalanced. This is a life-threatening condition. In this case, the general anesthesia must be stopped immediately. The active ingredient dantrolene is administered to the patient as an antidote. The patient may need to be monitored and ventilated for a long time after the occurrence of malignant hyperthermia. It is important that he can inform the doctors about this reaction for future interventions with general anesthesia.

Are you interested in this topic? Read more about this under: After-effects of general anesthesia


After general anesthesia, side effects such as nausea are quite normal.
The reason for this is that the patient is not only given various medications during the anesthesia, which ensure that he sleeps deeply and that he does not feel any pain during the operation, but also absorbs anesthetic gases.

The latter in particular leads to side effects such as nausea and vomiting after general anesthesia. Patients who do not smoke and who often get sick while traveling are particularly prone to experiencing side effects such as nausea after general anesthesia.

In general, women seem to experience side effects such as nausea, vomiting, and mild confusion more often after general anesthesia. If a patient also does not smoke, her brain is not used to any drug-like substances, so the drugs and anesthetic gases make her more difficult than a male patient who smokes regularly.

If a patient knows from her last operation that she suffers particularly badly from side effects such as nausea or vomiting after the general anesthesia, she can speak to the anesthetist (Anesthetists) mention this.
Shortly before the end of the operation, the anesthetist can inject the patient with a drug that can minimize the nausea after the operation. In general, this is mainly done for operations on the neck area, because the wounds in the neck area would make it bad if the patient had to vomit after the operation.

In general, however, it is not uncommon to experience side effects such as nausea or confusion after general anesthesia. Above all, the nausea usually disappears again within a day because the anesthetic gases have then been removed from the body and can no longer work in the brain on the receptors that make the patient sick.
In addition, it is usually the case that a patient does not feel any side effects such as nausea after general anesthesia and that he or she wakes up in the recovery room without any problems.
However, if there are side effects such as nausea after general anesthesia, the patient can inform a nurse or doctor at any time so that he can receive medication that suppresses the nausea.

You can find more information on this topic at: Nausea - causes, therapy and prognosis

Sore throat

In the case of general anesthesia, the patient is ventilated through a ventilation tube in the throat. This is necessary because with general anesthesia the muscles are immobilized with medication and the respiratory muscles become weaker and the respiratory center in the brain does not work normally.

This breathing tube leads to a sore throat in some people after the operation, because the mucous membrane is irritated. Sore throats are one of the most common after-effects of general anesthesia, but they usually subside after a few hours.

Would you like to learn more about this topic? Read our next article below: Sore throat and difficulty swallowing


Just like the sore throat, the hoarseness also comes from breathing with the breathing tube. The tube has to be led through the glottis into the windpipe and the glottis itself and the nerve responsible are irritated. The glottis can therefore not be opened completely normally after removing the ventilation tube, which leads to a hoarse pronunciation.

The hoarseness also subsides after a few hours in most cases. In rare cases, the vocal cords are injured during intubation, causing prolonged hoarseness.

Tooth damage

Intubation, the insertion of the ventilation hose, can in some cases lead to tooth damage. During intubation, the anesthetist uses a metal spatula, the laryngoscope, to lift the jaw and tongue to get a clear view of the larynx. If this metal spatula is used too jerkily or as a lever, it can hit your teeth.

Since some force is sometimes required during intubation, the affected teeth break off when they are struck. Tooth damage is difficult to prevent, especially with loose teeth. As a preventive measure, a silicone mouthguard can be placed between the teeth and the laryngoscope during intubation.

In the case of removable third teeth, these should be removed before the anesthesia. Patients should be advised of this risk prior to anesthesia. If tooth damage occurs during intubation, a dentist should be consulted promptly to initiate appropriate treatment for the injured tooth.

Other possible side effects after general anesthesia

a headache

In some cases, headache and headache with nausea occur after anesthesia.

Even if headaches are typical side effects of regional anesthesia such as spinal or epidural anesthesia, headaches are reported as side effects by some patients after general anesthesia.

If headaches occur after general anesthesia, the causes are rarely to be found in the anesthetic measures itself.
Most of the time, neither the drugs used nor the necessary procedures cause headaches directly. The classic side effects are nausea and confusion. However, headaches can occur after general anesthesia, even if they do not last long.

This is because the anesthesia affects the brain, which sometimes reacts sensitively to external stimuli.
Headaches after general anesthesia, however, have other reasons.One of them could be incorrect positioning during the operation. Headaches are conceivable as side effects, especially in long interventions that require the head to lie low.

It is also possible that the patient's fluid balance has become unbalanced during the operation. Although the anesthetist constantly monitors and corrects certain values ​​such as blood pressure and fluid balance, a headache-causing water shortage can occur.
These side effects are usually easy to treat by adding an infusion. Post general anesthetic headaches are more common in the elderly.

This has to do with the fact that this group of patients often brings accompanying illnesses with them, whereby cardiovascular problems and diseases of the lungs in particular can promote the occurrence of headaches.

In summary, it can be said that headaches are a rather rare side effect of general anesthesia and usually, if they occur, do not last long. Tablets such as paracetamol or ibuprofen can also be taken if you want to reduce the intensity and duration of the pain.
In contrast to general anesthesia, headache is one of the relatively common side effects associated with regional types of anesthesia that are restricted to the spinal cord.

You can read more detailed information on this topic in the following article: Causes of headache

Cardiac arrhythmias

People who already have a pre-existing heart condition can experience cardiac arrhythmias due to anesthesia. In most cases, these are elderly patients who suffer from cardiac insufficiency or atrial fibrillation and who are taking appropriate medication. But younger patients with inflammation of the heart muscle or congenital malformations can also be affected.

The anesthetic drugs have a very strong effect on the entire cardiovascular system and the volume administration also puts additional stress on the heart, which can trigger cardiac arrhythmias. In extreme cases, these mechanisms lead to ventricular fibrillation, which is equivalent to cardiac arrest.

You can find detailed information on this topic at: Arrhythmia

lung infection

Pneumonia can be triggered by very different mechanisms. General anesthesia is usually aspiration pneumonia. This is pneumonia caused by inhaling fluids or vomiting. Especially with general anesthesia, in which ventilation options other than classic intubation are used, vomit can quickly be inhaled.

Even small amounts are sufficient for this, so that even if the vomit is sucked off, pneumonia can develop. The most effective protection against aspiration pneumonia is classic intubation, as the path between the windpipe and esophagus is blocked.

Would you like more information about this? Read more about this under: Lung infection


Diarrhea can occur as a side effect following general anesthesia. However, this is usually unproblematic and quickly disappears. Just like nausea and vomiting, diarrhea can be caused, for example, by an intolerance reaction to the anesthetic or pain medication used.

If the diarrhea persists for a long time, care must be taken to balance the electrolyte balance and adequate fluid substitution, as the body loses both a lot of fluid and minerals through the watery stool. If diarrhea occurs after general anesthesia during abdominal surgery, it must also be taken seriously as a possible surgical complication.

If the diarrhea does not stop promptly, thorough follow-up checks should be carried out in the operating area in order not to overlook any other possible causes of the diarrhea.
Sometimes diarrhea following general anesthesia is also due to the decrease in stress.

Many people are very nervous about an upcoming operation, which can have an impact on digestion. Here, too, it is essential that a doctor should be examined if the diarrhea persists for a long time.

You can read more detailed information on this topic in the following article: Diarrhea - causes, therapy & prognosis

Hair loss

Many drugs have hair loss as a possible side effect and can often be detected in the hair even after months. The anesthetics, which are powerful drugs, are no exception. In addition, the body often reacts to stress with hair loss, and general anesthesia and an operation represent a pronounced stressful situation for the body.

The hair loss is usually only caused by more hair in the brush and not by bald spots. In addition, the hair loss is only a short-term consequence and stops by itself within a few days.

You may also be interested in the following article: Consequences of stress

Side effects on the eyes

A side effect of general anesthesia is that protective reflexes, such as blinking, do not work. Therefore, the eyes must be masked with a moisturizing gel to prevent the eyes from drying out.

Another side effect in people with increased intraocular pressure is a further increase in intraocular pressure due to the stress-induced increase in the sympathetic nervous system, a part of the autonomic nervous system. In this case, more aqueous humor is produced, which can drain more poorly. In rare cases, this leads to the detachment of the retina.


Depression and tiredness can occur as side effects or as a result of an operation with general anesthesia, but should usually subside after a short time. The main signs of depression are a depressed mood and a loss of interest and drive. You should consult a doctor, especially if these symptoms appear for the first time!

Larger operations can be a heavy burden not only on the body but also on the psyche. Situations typical of anesthesia such as loss of control, being at the mercy, feelings of numbness or fear of death can reactivate a trauma, particularly in the case of mentally pre-stressed patients or patients who have suffered a physical or emotional trauma.

Since the drugs used during anesthesia intervene briefly in the metabolism of the brain and depressive illnesses are associated with an altered brain metabolism, it cannot be ruled out that there is a connection, but this theory has not been proven. To prevent depression and the fear of the Before starting the procedure, the process and other questions should be discussed in detail with the responsible doctors.

Depression affects thousands of people every year and should not be underestimated. The next article will explain everything to you in detail about preventing depression: How to prevent depression

Memory problems

In the context of anesthesia, specific agents are often administered that are intended to induce retrograde amnesia. This means that patients should lose their memories after an often uncomfortable and painful procedure. Drugs that cause this memory-altering effect are, for example, benzodiazepines, which are administered to calm you down before the operation.

Anesthetics such as propofol or etomidate cause a loss of consciousness and anterograde amnesia, so that the patient cannot remember the time during the operation. These drugs act on so-called GABA receptors in the brain and lead to amnesia.

However, these receptors also have the property of blocking the transition of information from short to long-term memory, which is intensified by the anesthetic drugs.

This effect is also desirable to a minor extent and ensures that the patient does not remember the previous operation (retrograde amnesia).
This influence on the memory only takes place during the active time of the respective medication (possibly a few hours after the operation). Long-lasting, permanent disorders and changes in memory are usually not to be expected from anesthesia.

Restricting memory beyond the end of the operation is undesirable. Although this is mostly only temporary, it can also last for months or, in rare cases, be permanent. Older patients over 60 years of age are particularly affected. Patients over 60 are monitored more closely to prevent this complication.

In addition, attempts are being made to use regional anesthesia procedures more frequently, which have a lower risk of such complications.
In the case of permanent memory impairment after an operation under anesthesia, physical causes or complications during the operation should be excluded.

Duration of memory disorders

These types of side effects after general anesthesia are usually self-limiting, so that the confusion disappears after hours or at most a few days. However, it is not infrequently described that even when the patient is discharged, there may still be isolated deficits in the ability to remember and think. For example, the car is no longer found in the parking lot.

In some cases, what is known as cognitive dysfunction can occur as a much more negative type of side effect after general anesthesia. This is confusion that only occurs days or weeks after an operation and usually has a worse prognosis than postoperative delirium.

Concentration is restricted and the ability to think is reduced. In older people, this form of confusion sometimes turns into dementia, which cannot be reversed. What exactly causes all these side effects after general anesthesia is poorly understood. Overall, confusion is one of the frequent side effects that are taken into account. A clinic should only be returned to if symptoms persist.

Side effects of general anesthesia in the elderly

Elderly people are generally exposed to the same risks under general anesthesia as younger people. Injuries can occur when inserting the ventilation tube (intubation), afterwards sore throats caused by slight injuries to the mucous membrane can occur.

Injury to teeth during intubation is also possible. Furthermore, allergic reactions to the anesthetics or painkillers used can occur. In the area of ​​the puncture site of venous and / or arterial accesses, bruises may remain or inflammation may develop. Aside from these general anesthetic risks, there is some evidence that general anesthesia affects older people more than young people.

The already aged organism often takes longer to fully recover from general anesthesia. In addition, so-called transit syndrome, or postoperative delirium, occurs more frequently in patients aged 60 and over after the operation. This is characterized by persistent states of confusion after waking up from general anesthesia.

As a result, most patients tend to be apathetic and withdrawn postoperatively (hypoactive delirium), other patients suffer from hallucinations and severe states of restlessness (hyperactive delirium).

Other suspected side effects of general anesthesia in old age are a prolonged impairment of thinking and an increased risk of dementia. However, the latter is controversial and not clearly attributable to general anesthesia. It could also be the operation itself, which allows a previously unknown dementia to progress faster due to the associated physical stress.

It is noticeable, however, that older people often need several months following general anesthesia to find their way around their everyday life completely and without restrictions. The exact circumstances of the cognitive impairment of older people following general anesthesia have not yet been conclusively clarified, as ongoing studies are delivering sometimes contradicting results.

Forgetfulness after general anesthesia

Some people, especially the elderly, develop continuity syndrome after using general anesthesia. In terms of the behavior of those affected, this resembles dementia, but it usually disappears after a few days.

A slight confusion in the first few hours after anesthesia can, however, be observed in almost all those affected and usually subsides within a few hours. This is an aftereffect of the anesthetic medication, which has not yet been completely broken down and is therefore a natural reaction of the body.

Confusion after general anesthesia

Some of the substances used in anesthesia cause confusion in patients. These substances include benzodiazepines such as midazolam, which are administered to calm you down before an operation. Major surgical interventions can lead to confusion, disorientation and even aggressive behavior.

A term for this condition that is now somewhat out of date is the so-called “transit syndrome”, as the changes usually recede completely (are consistent). There is no known therapy here. However, the patients should be monitored by means of an ECG and blood pressure control.

The state of confusion can last for hours, days and in rare cases even longer. Other physical causes of confusion after surgery with anesthesia include low blood sugar or a lack of oxygen. Surgical complications, such as encephalopathy (a disease of the brain), also lead to confusion and should be treated by a doctor.

This side effect can be easily understood through the profound influence on processes in the brain and consciousness such as the elimination of motor and sensory perception.

The technical term for confusion after general anesthesia is "postoperative delirium'.
Confusion is one of the most common side effects of general anesthesia, with 5-15% affected patients, which can increase by up to 50% in difficult and long-lasting operations.

There are big differences in the form, duration and time of occurrence. In general, confusion can occur in any patient, the elderly being the most common. As a rule, the confusion begins right after waking up or a few hours afterwards and does not last long. During this time, patients are severely limited in their thinking and attention.

Both temporal and spatial orientation are difficult in many cases. In addition, disturbances of the sleep-wake cycle can occur as further side effects and problems such as loss of appetite and lack of affect can be observed.

The majority of patients suffer from the hypoactive form of delirium, that is, they lie quietly in bed with slowed reflexes and reactions. There is a tendency to sleep. About 15% develop a hyperactive form with agitation and delusions.

Side effects of general anesthesia in children

Certain side effects can also occur in children following general anesthesia. Very young children are often very restless, crying, or screaming for 10-15 minutes after they wake up. This is due to a brief state of confusion caused by general anesthesia. Some children complain of nausea or vomit following general anesthesia.

However, this is not very common. In addition, the ventilation tube inserted before the operation can lead to a sore throat, which will quickly improve as soon as the child has eaten and drunk something.

Otherwise, the same risks and side effects of general anesthesia apply to children as to adult patients. For example, there may be intolerance to the medication, bleeding or bruising in the area of ​​the puncture site of venous / arterial accesses and in the case of nerve damage, sensory disturbances may remain in the corresponding area.

Overall, however, nowadays general anesthesia are uncomplicated in the vast majority of cases, even in children.

Read more on the subject at: General anesthesia in children

Duration of side effects after general anesthesia

Unfortunately, it is not always possible to predict in advance how long side effects will last after general anesthesia.
However, the duration of side effects after general anesthesia is usually limited to a certain period of time, depending on how long the operation lasted, whether there were any complications and how the patient reacts individually to the anesthetic gases and the medication administered.

Since especially female patients who do not smoke and who get sick quickly, more often have problems with the after-effects of anesthesia, these patients often experience a longer duration of side effects after general anesthesia.

The reason for this is the fact that various receptors are addressed in the brain during anesthesia, which, for example, are also addressed during smoking. If a patient is used to this, because he smokes more often, the brain reacts to the usual stimulus no differently than usual.

However, if a patient is not used to this stimulus, the stimulation of the receptors by the anesthetic gases and the medication given during general anesthesia leads to an imbalance in the brain. The patient notices this after the operation through side effects such as confusion and nausea.

How long the side effects persist after general anesthesia depends, on the one hand, on how well the brain copes with the substances that are administered during the operation.
On the other hand, the duration of the side effects after general anesthesia depends on how quickly the patient's body can process the drugs and gases administered under general anesthesia. This depends on the one hand on the physical fitness of the patient and on the other hand on the function of the liver and kidneys.

In elderly patients in particular, the duration of side effects after general anesthesia is often much longer than in healthy and fit patients. How long the side effects of general anesthesia will last is difficult to estimate, but the patient usually has to expect to struggle with the side effects the first day after a major operation under general anesthesia.

From the second day onwards, however, there should be a clear improvement up to and including freedom from symptoms. In rare cases, however, the duration of the side effects after general anesthesia may last much longer and the patient may still experience nausea or recurring states of confusion for up to 6 weeks after the operation.
In addition, in rare cases, the duration of the side effects after general anesthesia is so long that the patient develops a disease of its own.

Depression in particular (postoperative depression) that occurs after an operation under general anesthesia can be triggered by general anesthesia and will not go away on its own. How long the side effect of general anesthesia lasts in this case depends above all on the personal commitment of the patient, as he should consult a psychologist or psychiatrist as early as possible in the event of depression with lack of drive and listlessness so that the depression cannot solidify.

In general, however, a so-called chronification of a disease after general anesthesia is very rare and the duration of the side effects after anesthesia is often only a few hours to days.

How long the side effects will last after general anesthesia can never be precisely estimated.
In general, the longer the operation and the more susceptible the patient to the anesthetics (because he doesn't smoke, he gets sick easily etc.), the longer the side effects last after general anesthesia.