When Does Fever After Surgery Become a Concern?

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

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 your temperature could go up after you have surgery. It also discusses ways to prevent and treat a fever.

Taking Your Temperature

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. You could 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 a temperature on their forehead or in the ear.

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

Causes

Surgery-related fevers can be caused by:

• Infections in a specific area, such as pneumonia, urinary tract infection, an infected incision, or abscess
• Septicemia, an infection that reaches the blood
• Blood transfusion
• Deep vein thrombosis (DVT), blood clots that form in veins
• Peritonitis, an infection in the abdomen caused by a leak at the surgical site

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

Low-Grade Fever

A fever is considered low-grade if your temperature is 1 or 2 degrees above the normal reading of 98.6 degrees. It's a good idea to let your surgeon 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 surgeon right away. You may need medical attention.

It's also a good idea to let your surgeon 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 surgeon know if you have a fever in this range. You may need to take some steps 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.

Treatment

A low-grade fever may not need treatment other than medications such as Tylenol or Advil. These medications are used to bring down your 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 medication may 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 infection is not the only reason for a spike in temperature.

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

Prevention

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.

Summary

It isn't uncommon 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 surgeon 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're having nausea, vomiting, shortness of breath, disorientation, or signs of wound infection.

A Word From Verywell

A fever can be alarming when you are recovering from surgery. 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 you should watch it closely and let your healthcare provider know if it worsens.