When Does Fever After Surgery Become a Concern?

A fever after surgery is one of the most common complications that patients face. In fact, over half of all surgery patients will have a higher than normal temperature in the days following their procedure, for various reasons.

causes of fever after surgery
Verywell / Emily Roberts

The good news about postoperative fevers is that most are not serious and can be easily treated with ibuprofen or acetaminophen, or nothing at all. In fact, for some low-grade fevers, no treatment is necessary. The bad news is that in some cases a fever after surgery can be the first sign of a major problem.

Any fever after surgery needs to be taken seriously and monitored closely. 

If you have a fever after your surgery, your surgeon may or may not prescribe antibiotics. Some surgeons prefer to prescribe "prophylactic" antibiotics for all of their surgery patients. Others will wait until testing indicates that antibiotics are necessary. In some cases, an antibiotic won't successfully treat a fever, because infection is not the only reason for an increase in temperature.

The more time that passes between the day of your surgery and the day of your fever, the less likely the fever is to be related to your surgery, especially if weeks have passed with no issues.

Taking Your Temperature

Taking your temperature daily in the week following your surgery is a smart and easy way to keep an eye on your health during your recovery. A fever can be an early warning that something isn't quite right, even before you start to feel ill.

For adults, taking an oral (mouth) temperature is the most common method; however, if you have been drinking hot or cold beverages, wait 20 minutes or take an axillary (armpit) temperature instead.

For infants, a rectal (anal) temperature may be easiest. Children, like adults, should avoid taking oral temperatures after drinking hot or cold beverages, and may do best with devices that take a temperature at the forehead or ear. Ideally, you will check your temperature at the same time each day.

Causes of Fever After Surgery

Fever for reasons related to the surgery include:

Non-Surgical Reasons for Fever

Just because you had surgery recently does not mean that surgery is the reason for the fever. It is possible to have the flu a few days after surgery, just as it is possible to have an unrelated infection.

Common non-surgical causes of fever:

  • Viruses, such as the flu or the common cold
  • Strep throat, a bacterial infection
  • Neurological ​fever, a type of fever is caused by a brain injury that will not respond to normal interventions, such as Ibuprofen
  • Other infections unrelated to surgery

Low-Grade Fever

A low-grade fever is the most common complication after surgery. You should make your surgeon aware if you have a low-grade fever, which is a temperature that is 1 or 2 degrees above the normal reading of 98.6 degrees.

A fever of 99 is very common after surgery, especially the first week after surgery with a healing incision. A fever, along with an incision that does not appear to be healing well is absolutely a cause to update your surgeon and to possibly seek medical attention.

If your low-grade fever persists for several days, notify your surgeon that the fever has not resolved.

Moderate Fever

A fever ranging from 100.6 to 102 F is considered a moderate level of fever. Report the fever to your surgeon, and take action if your surgeon feels it is necessary.

Seek medical attention if your fever is accompanied by symptoms such as nausea, vomiting, an unexplained increase in pain, disorientation, drainage or angry redness around your incision, or any other condition that suggests that your recovery is not going as planned such as shortness of breath.

A fever greater than 102 in an adult is high enough to warrant a trip to the emergency room. Also, seek medical attention if your fever does not respond to a dose of Advil (ibuprofen) or Tylenol (acetaminophen) after an hour.

High Fever

A high fever, which is a fever higher than 102 F in adults, requires immediate medical attention. This could mean that you have a serious infection, there is a problem with your surgical site, or you are reacting to a medication.

Notify your surgeon if you develop a fever over 102 F and seek medical help, whether it is from your surgeon, family practice physician, urgent care, or emergency room.

You could potentially receive antibiotics, have blood tests and blood cultures drawn, or even be seen by your own surgeon if they are very concerned.


The cause of a fever may not be obvious, and a low-grade fever may not even warrant treatment beyond over the counter medications such as Tylenol or Ibuprofen. These medications are used to decrease body temperature.

Often, a fever between 99 and 101 is allowed to run its own course without medication. Higher temperatures typically require greater attention and may require testing to identify the cause.

If you are taking pain medication that contains Tylenol or Advil routinely to manage your pain after surgery, you could potentially have a fever and not realize it as these medications work to reduce fever as well as pain.

Bringing down a fever with medication may not be good enough. You may have an infection that requires prescription antibiotics to treat, specialized wound care, or both. With higher fevers, blood, urine, and wound cultures are often done to make sure the blood, urinary tract, and surgical wound are not growing a bacterial infection. 

Many surgeons will err on the side of caution and begin antibiotics before the culture results are available in order to prevent an infection that may be present from worsening.


You can take simple steps to help prevent an elevated temperature after surgery by working to prevent an infection.

A Word From Verywell

A fever can be alarming when you are recovering from surgery, but it is important to keep in mind that a low-grade fever is very common—almost expected—in the days following surgery. A mild fever isn't an emergency, but it should be watched closely and your healthcare provider notified if it worsens.

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Article Sources
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  1. Abdelmaseeh T, Oliver T. Postoperative Fever. StatPearls Publishing. 2019.

  2. Meier K, Lee K. Neurogenic Fever: Review of Pathophysiology, Evaluation, and Management. J Intensive Care Med. 2017;32(2):124-129.  doi:10.1177/0885066615625194

  3. Rao J, Singh A. Evaluation of postoperative pyrexia in general surgery patients in Medicity Institute of Medical Sciences, Ghanpur, Medchal, India. International Surgery Journal. 2018;5(6). doi:10.18203/2349-2902.isj20182014

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