Is a Fever After Surgery Serious? (2024)

A fever after surgery, also called post-operative fever, is one of the most common complications patients face. Estimates reveal that fever occurs early in the postoperative period in 20% to 90% of patients, and both children and adults can experience fever after surgery.

Is a Fever After Surgery Serious? (1)

The good news is that most fevers are not serious. They can be treated with Advil (ibuprofen) or Tylenol (acetaminophen). Some low-grade fevers don't need treatment at all. The bad news is that a fever after surgery can sometimes be the first sign of a problem.

This article explains some of the reasons you could have a fever after surgery. It also discusses ways to treat and prevent a fever.

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

Causes of Fever After Surgery

Surgery-related fevers can result from a variety of causes.

Lung Problems

Two post-surgery complications that can cause fever include atelectasis and pneumonia.

Atelectasis is one of the most common causes of fever after surgery, occurring in 90% of people receiving general anesthesia. Anesthesia causes the little air sacs (alveoli) within your lungs to deflate, leading to areas of the lung collapsing.

Pneumonia is a lung infection that inflames the air sacs, sometimes filling them with fluid or pus. The infection can come from bacteria, viruses, and fungi, or can be caused by aspirating (inhaling) food or liquid.

Urinary Tract Infection (UTI)

A urinary tract infection (UTI) can cause a fever post-surgery. If you had a urinary catheter during your surgery, you have a greater chance of getting a UTI.

Other Infections

Other infections that would cause fever after surgery include:

  • An infected wound or abscess
  • An infected incision where surgery was done or from a central line site
  • Septicemia: an infection that reaches the blood
  • Peritonitis: an infection in the abdomen caused by a leak at the surgical site

Blood Clots

A deep vein thrombosis (DVT) is a blood clot that forms in a vein, usually the leg. If you aren't moving as much as usual after surgery, DVTs are more likely to develop.

A pulmonary embolism is another type of blood clot that can lodge in the lungs.

Medication Reaction

Post-surgery fevers can also be caused by blood transfusions or medicines given during surgery that cause a bad reaction. The fever may clear up on its own, but may also be a serious reaction that needs to be treated immediately.

Non-Surgical Causes

Just because you had surgery recently does not necessarily mean the procedure is the reason for the fever.It is possible to have the flu a few days after surgery. It's also possible to have an unrelated infection.

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

Common non-surgical causes of fever include:

  • Viruses, such as the flu or a cold
  • Strep throat, a bacterial infection
  • Neurological ​fever caused by a brain injury
  • Other infections


A fever may or may not be related to your surgery. Fevers can come from infections that are localized near your surgical wound or infections somewhere else in your body.

Taking Your Temperature

A fever after surgery is defined as a temperature higher than 100.4 F (38 C) on two consecutive postoperative days or greater than 102.2 F (39 C) on any postoperative day.

If you are staying in the hospital after surgery, the healthcare staff will take your temperature regularly.

If you go home right after surgery, taking your temperature daily in the week after surgery is a smart and easy way to keep an eye on your health as you recover. A fever can be an early warning that something isn't quite right, even before you start to feel ill.

Adults can usually get an accurate reading by taking their temperature by mouth. If you have had a hot or cold drink, wait 20 minutes before checking your temperature. You can also place the thermometer under your armpit instead.

For infants, it may be easier to use a rectal thermometer.

Keep in mind that children should also avoid hot or cold drinks if you're taking their temperature by mouth. Some children do best when you use a device that reads the temperature on their forehead or in the ear.

Ideally, check your temperature at the same time each day.

Low-Grade Fever

A fever is considered low-grade if your temperature is one or two degrees above the normal reading of 98.6 degrees. It's a good idea to let your healthcare provider know if you have a low-grade fever.

A fever of 99 F is very common, especially in the first week while your incision is healing. If you have a fever and your incision isn't healing well, tell your healthcare provider right away. You may need medical attention.

It's also a good idea to let your healthcare provider know if a low-grade fever does not go away after a few days.

Moderate Fever

A fever between 100.6 and 102 F is considered moderate. Let your healthcare provider know if you have a fever in this range. They may recommend treatment to resolve the problem.

It's important to seek medical care If you have a fever plus any of these symptoms:

  • Nausea
  • Vomiting
  • Unexplained increase in pain
  • Disorientation or confusion
  • Pus or drainage from your incision
  • Redness near your incision
  • Shortness of breath

These symptoms can be a sign that a problem is developing.

You should also seek medical care if your fever does not come down within an hour after a dose of Advil or Tylenol.

High Fever

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

Let your healthcare provider know if you have a fever over 102 F. Seek medical help, whether it is from your surgeon, your family physician, urgent care, or the emergency room.

Treatment for Post-Operative Fever

A low-grade fever may not need treatmentother than medications such asTylenol or Advil.These medications are usually effective for treating a fever.

If you are taking pain medication that contains Tylenol or Advil to manage your pain, you could have a fever and not realize it. That's because these medications typically lower fever and treat pain at the same time.

Bringing down a fever with medicationmay not be enough.You may have an infection that requires prescription antibiotics. You may also need specialized wound care.

In some cases, an antibiotic won't successfully treat a fever. That's because antibiotics won't treat an infection caused by a virus or fungus and an infection is not the only reason for a spike in temperature.

If you have a high fever, your healthcare provider may doblood, urine, and wound cultures.A culture allows your healthcare team to identify which bacteria or other organism is growing in a sample of tissue or fluid. Once your healthcare team knows which organisms are there, they can choose a medication to target the infection.

Some surgeons begin antibiotics before the culture results are available, and some prescribe antibiotics for all of their surgery patients. Their goal is to prevent any infection from getting worse.

Others wait until a test shows that antibiotics are necessary.

How to Prevent Fever After Surgery

You can take simple steps to prevent an infection.

  • Check your incision daily until it is completely healed.
  • Wash your hands before and after touching your incision.
  • Drink lots of water to help prevent a urinary tract infection.
  • Do proper incision care and dressing changes.
  • When physically able and approved by your healthcare team, increase mobility and activity.


It is very common to have a slight fever after surgery. If you have a fever between 99 and 101 F, it may go away on its own or with over-the-counter medication. Even so, it's a good idea to let your healthcare provider know about it.

A fever could be a sign that you're developing an infection somewhere in your body. Your healthcare team can do tests to determine exactly what's causing the problem. You may need antibiotics or another treatment.

A fever over 102 F requires medical attention. It's also vital to get medical care right away if you have nausea, vomiting, shortness of breath, disorientation, or signs of wound infection.

Frequently Asked Questions

  • Can you get a fever after tooth extraction?

    Yes, you can get a fever after tooth extraction, such as during the removal of wisdom teeth. If a person shows signs of a fever after tooth extraction, they should contact their healthcare provider. Even if it is a low-grade fever, it is better to be safe than sorry.

  • Is it normal to have chills after surgery?

    It is normal to have chills after surgery. While it doesn't happen to everyone, chills, shivering, and overall coldness are a few side effects of being under general anesthesia. These effects might be caused by the anesthetic affecting nerve signals being transferred to the brain, but the exact reason for chills is unknown. Your healthcare provider should notify you of these possible side effects before surgery.

Is a Fever After Surgery Serious? (2024)


When should I be worried about a fever after surgery? ›

If your body temperature is higher than usual by more than two degrees, it's best to contact your doctor right away. You may need additional treatment, including: antibiotics to treat an infection, either near the surgical site or in another part of your body.

Is it OK to have fever after surgery? ›

Postoperative fever is a temperature higher than 102.2 F on any day after surgery or 100.4 F on any two consecutive days after surgery. Fever after surgery is very common. Most cases are harmless and go away on their own.

How much fever is normal after surgery? ›

A have a low-grade fever (less than 101.5°F) during the first week after your surgery is common. This is a normal response by your body to the stress of surgery.

Does a fever after surgery always mean infection? ›

In most patients, postoperative fever is due to a benign cause and resolves spontaneously. Patients with deep vein thrombosis and pulmonary embolism usually have a low-grade fever that resolves within a few days of treatment.

When should I go to the ER after surgery? ›

Common postoperative reasons to be readmitted to the hospital are: Postoperative infection. Fever, worsening pain, skin warmth, redness at the surgical site, drainage like pus from your surgical site and ongoing lack of energy can signal a postoperative infection that may require medical treatment like IV antibiotics.

What are the signs of sepsis after surgery? ›

How does sepsis occur after surgery?
  • Increasing redness around the incision.
  • Pus or other fluid coming from the incision.
  • Warmer than usual skin around the incision.
  • Increased pain around the incision.
  • Fever.
  • Fatigue.

Why is day 3 after surgery the worst? ›

Tissue injury, whether accidental or intentional (e.g. surgery), is followed by localized swelling. After surgery, swelling increases progressively, reaching its peak by the third day. It is generally worse when you first arise in the morning and decreases throughout the day.

What are the 5 W's of postoperative fever? ›

Wind, water, walking, wound, wonder drug.

What is a high temperature for a fever? ›

What is a high temperature? Normal body temperature is different for everyone and changes during the day. A high temperature is usually considered to be 38C or above. This is sometimes called a fever.

How long after surgery can you get an infection? ›

Types of surgical site infections

An SSI typically occurs within 30 days after surgery. The CDC describes 3 types of surgical site infections: Superficial incisional SSI. This infection occurs just in the area of the skin where the incision was made.

Why is temperature important after surgery? ›

“Consequently, body temperature typically decreases about four degrees Fahrenheit in unwarmed surgical patients. This sort of moderate hypothermia can cause serious complications including blood loss and wound infections.” Warming surgical patients to help prevent hypothermia is now the standard-of-care.

What is considered a low-grade fever? ›

While body temperatures vary, most of us have an internal temperature around 98.6 degrees Fahrenheit. A temperature slightly higher than that is still normal. When your temperature is between 100.4 and 102.2, you have what is considered a low grade fever.

What is a spike in temperature after surgery? ›

Pyrexia (fever) refers to a raised body temperature, typically greater than 37.5c. It is common in surgical patients, either normal immediate post-operative response or as feature of a specific post-operative complication.

What is the most common infection after surgery? ›

Infections after surgery are caused by germs. The most common of these include the bacteria Staphylococcus, Streptococcus, and Gram negative bacilli.

Does a fever always mean bacterial infection? ›

So if you have a fever, basically it [almost always] means you have an infection," Dr Young said. But both bacteria and viruses can cause fevers and there's no specific difference between a fever caused by bacteria and one caused by viruses.

What is the most common post op fever? ›

The most common causes of postoperative fever are often summarized for medical students by a mnemonic beginning with the letter W. The classic list consists of five W's – Wind, Water, Wound, Walking, and Wonder Drugs, but two other causes should also be considered – Wing/Waterway and (W)abscess.

What are 5 common causes of post op fever? ›

Title: Cause of Post-Operative Fever
  • Wind - Pneumonia, aspiration, pulmonary embolism, and atelectasis.
  • Water - urinary tract infection.
  • Walking - Deep Venous Thrombosis or pulmonary embolism.
  • Wound - surgical wound infection.
  • Wonder drugs - Drug fever, or infection due to indwelling lines, or a reaction to blood products.
Jan 18, 2014

When should I be worried about a 100.5 fever in adults? ›

Adults. Call your health care provider if your temperature is 103 F (39.4 C) or higher.

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