What Is Postoperative Fever?

Written by Sadiya Ansari
Medically Reviewed by Zilpah Sheikh, MD on August 13, 2025
5 min read

Fever after surgery is very common. Most cases are harmless and go away on their own.

Postoperative fever is when your temperature goes above 102.2 F on any day after surgery or above 100.4 F on any two consecutive days after surgery.

Postoperative fever affects up to 90% of people who have surgery. Any type of surgery causes injury and inflammation. Part of your body's response to this injury and inflammation can be fever. Aside from this inflammatory response, atelectasis is the most common cause of postoperative fever.

Fever after surgery can be serious, so it needs to be examined. There are a lot of different conditions that can cause postoperative fever. Doctors use the Five Ws to classify the conditions that can cause you to run a fever after surgery.

Wind. This category addresses problems with your lungs, including pneumonia. It's an infection in your lungs. Pneumonia is the third most common complication after surgery and usually leads to a longer hospital stay. In some cases, it can be dangerous and even fatal. ‌

Water. This refers to a fever caused by a urinary tract infection. If you had a urinary catheter during your surgery, you have a greater chance of getting a UTI.

Wound. Infections that happen at or near the surgical site are referred to as surgical site infections. You can have a superficial surgical site infection in the skin. It can also be a more serious infection involving the tissues and organs. 

Walking. Fevers that are caused by deep vein thrombosis fall under this category. Deep vein thrombosis happens when you get a blood clot in a vein deep inside your body, usually in your leg. You have a better chance of deep vein thrombosis after surgery because you aren't moving as much as usual. A pulmonary embolism, which is a blood clot in your lungs, is also in this category.‌

Wonder drugs. This category covers fevers caused by medicine and blood products. If you're given medicine during your surgery that causes a bad reaction, you may get a fever. It can sometimes be short-lived and clear up on its own. It may also be a serious reaction that has to be treated immediately.‌

There can be other causes as well, including:

You can expect to have a slight fever in the first two days after you have surgery. Unless you have other symptoms as well, your doctor will probably monitor your condition. You likely won't need a workup.

If you have other symptoms or a high or persistent fever, you will need additional tests to find out the cause. Your doctor may order other tests, including: 

How your medical team will treat your postoperative fever will depend on the cause. Options include:

  • Oxygen
  • IV fluids
  • Antibiotics or other medicines
  • Incentive spirometry, which is a device to help you expand your lungs
  • Blood thinners
  • Compression stockings
  • Referral to a specialist

What can I do at home to manage postoperative fever?

  • Rest.
  • Hydrate.
  • Take over-the-counter medication such as ibuprofen.
  • Track your temperature and any other symptoms.
  • Look at your wounds for any changes.

If you have any of the following signs of infection after your surgery, let your doctor know: 

  • A fever higher than 101 F
  • A low-grade fever for more than 48 hours
  • Pus or more drainage from your incision
  • More swelling
  • Redness or warmth at the site of your incision
  • A foul smell coming from the incision‌

You should also call if you're coughing up or vomiting blood, or if you have:

  • Severe headache or other pain
  • Loss of appetite
  • Problems breathing
  • Chest pain
  • Dark or bloody bowel movements
  • A tear in your incision
  • Redness or pain near your incision
  • Constipation or diarrhea
  • Very tired feeling‌

Even if you don't have any of the symptoms above, call your doctor if you just generally feel worse than when you left the hospital, or if you have any other symptoms that concern you.

If you have a weakened immune system and are concerned about your fever (even if your symptoms aren’t this advanced), contact your doctor.

"Although some fevers are completely benign, some can be red flags for something going on underneath," says Shalwa Mohidul, MD, who specializes in emergency general surgery at Emory University. 

Possible complications that a fever might be a sign of include:

  • Infection
  • Deep vein thrombosis
  • Pulmonary embolism
  • Atelectasis, which can have further complications, such as pneumonia
  • An inflammatory response to the stress of surgery, which can develop into systemic inflammatory response syndrome (SIRS). This can attack your body, damage organs, and even cause death.
  • Sepsis, which happens when the immune system overreacts to an infection and triggers SIRS. It is life-threatening and requires immediate treatment.

A mild fever after surgery is common and usually reflects your body’s response to the stress of a procedure. You can treat it at home by resting, staying hydrated, and using over-the-counter medication for comfort. It’s important to track your fever and symptoms. Contact your doctor if your fever rises above 101 F, a lower-grade fever lasts longer than two days, or you have any other concerning symptoms along with a fever.

Can stress cause postoperative fever? 

No, day-to-day stress can't cause a fever; it’s the stress your body has been put under during surgery that causes a fever.

Is fever after surgery always a sign of infection?

No, a low-grade fever is common after surgery. The condition could be a sign of something other than an infection.

What causes chills after surgery?

After surgery, chills can be a sign of many things, including infection or your body resetting its temperature after going under anesthesia.

Is 99.9 F temperature normal after surgery?

Yes, this is considered normal after surgery, but if a low-grade fever continues for two or more days or if there are signs of infection, contact your doctor.