Common side effects and minor risks associated with anesthesia

Most side effects of general anesthesia are minor in people who are otherwise healthy and they can be easily managed by your anesthesia care team. Some of the most common ones are discussed below.

1. Nausea and vomiting after surgery (also called postoperative nausea and vomiting)

How common is it?
Post-operative nausea and vomiting (PONV for short) is one of the most common side-effects that occurs in the first 24 hours after your surgery. It affects 20-30% of patients. However, nearly half of all patients who do not have PONV in the hospital, experience nausea and/or vomiting in the first few days after discharge.

Who is at risk?

For adults, there are many factors that increase the risk of having PONV. Firstly - being female, not smoking (the only benefit from smoking, but definitely not worth it!) and having a history of motion sickness or PONV after a previous surgery.

Then some anesthetic drugs and painkillers - most commonly those gases that keep you asleep, the morphine-like painkillers (called opioids in medical terms) and laughing gas (called nitrous oxide in medical terms). The morphine-like painkiller’ used for pain relief after surgery (commonly used by the acute pain service) do a good job in relieving pain, but are a common reason for nausea on the first and second day after surgery.

Lastly, some surgeries are known to carry a high risk for PONV. These include surgery on the ear or intestines and laparoscopic surgery (key-hole surgery) for operations on the female organs.

If more of these factors apply to you - the higher your risk to have PONV. See below.

Can it be prevented and/or treated?

It is important to inform your anesthetist that you had this problem in the past. Your anesthetist can choose a different way of giving your anesthetic. When possible, a regional anesthetic (where the ‘gases’ and ‘morphine-like’ painkillers are not needed) significantly reduces your risk of having PONV in the first few hours after your surgery.

The drugs used to prevent or treat PONV are known as antiemetics. If you are a low-risk patient - no drugs to prevent PONV are needed. If you are at moderate risk, at least one drug should be given to prevent PONV. If you have many risk factors (see paragraph above) a mix of ‘antiemetics’ should be used for prevention. If our efforts to prevent your PONV fail, antiemetics will also be offered in the recovery room.

The morphine-like painkillers used for pain relief after surgery (commonly used by the acute pain service) does a good job in relieving pain, but are a common reason for nausea on the first and second day after surgery.

Key reference:
Guideline for the management of postoperative nausea and vomiting.
J Obstet Gynaecol Can 2008; 30:600-616

2. Sore throat

How common?

Sore throat and hoarseness in the first hours to days after anesthesia occurs in up to 40% of patients (13).

Who is at risk?

The following increase your risk:. Being female; younger than 50 years old and having a general anesthetic lasting more than 3 hours.

Can it be prevented and/or treated?

Having a regional anesthetic (link bold word to regional anesthesia) will completely prevent this problem. However, if you need a general anesthetic, your anesthetist may chose a smaller size for the device used to help you breath during surgery. Some drugs have also been proven to be beneficial, such as a freezing medication or an anti-inflammatory medication. In addition, the use of some over the counter substances such as Tantum or Strepsils can help alleviate acute sore throat pain.

Key reference:
Complaints of sore throat after tracheal intubation: a prospective evaluation.
Eur J Anaesthesiol 2005; 22:307-311.

3. Teeth damage

How common is it?

Teeth damage is a rare but very unfortunate complication of general anesthesia, roughly occurring in 1:2000-cases. The most frequently injured teeth are the upper front ones (the upper incisors) (25;26).

Who is at risk?

Patients mostly at risk for dental injury are those with poor dental health and where the anesthetist have had difficulty to ‘get the breathing tube down’ (called a ‘difficult intubation).

Can it be prevented?

Although the anesthetists are always very careful, prevention of dental damage is not always possible. Several devices have been used such as mouth-guards and bite-blocks but provide no guarantee. Moreover, these devices may make it more difficult to place to place the breathing tube.

Key reference:
Dental injury associated with anesthesia: a report of 161,687 anesthetics given over 14 years.
J Clin Anesth 2007; 19:339-345.

4. Shivering/Chills

How common is it?
Shivering after an anesthetic is an occurs in the early recovery phase after anesthesia in approximately 25-50% of patients.

Who is at risk?

Cooling down is the most common cause. Other causes including include pain, fever and stress after surgery. It seems to be more common in males and after longer surgeries, but it is quite rare in elderly patients.

Can it be prevented and/or treated?

While we try to reduce the drop in body temperature, is itit is impossible to completely prevent it. There are also a few drugs that can be used either to prevent and/or to treat post-operative shivering.

Written by:
Dr  Sinziana Avramescu, MD (Resident Physician)

Reviewed by:
Dr Martin van der Vyver, MBChB, FRCPC (Specialist Anesthetist)

Date created:
October 22, 2010

Key reference:

Postanaesthetic shivering. Epidemiology, pathophysiology and approaches to prevention and management.
Minerva Anestesiol 2003; 69:438-442.