Why your body runs warm after surgery
Surgery is controlled injury. The body responds with inflammation, and inflammation can raise your temperature even when there is no infection at all. The StatPearls review of postoperative fever (Azmat and Martingano, updated 2026) explains that a mild fever in the first 48 to 72 hours after routine surgery is often considered normal. It cites a working threshold of up to 38.6 °C (101.5 °F) for that early window. In that period the cause is usually not infectious. Likely culprits include the body's inflammatory response, the effects of anesthesia, fluid shifts, small areas of collapsed lung, or a collection of blood.
That is reassuring, but it is not a reason to ignore a thermometer. "Normal early fever" is a judgment for your surgical team, made with the rest of your symptoms in view. It is not a rule to apply on your own.
Timing is the most useful clue
The StatPearls review groups post-operative fever by when it starts, because the likely causes shift over time.
| When it starts | What clinicians tend to consider | What you should do |
|---|---|---|
| Within 24 hours | Mostly reactions to the surgery and anesthesia themselves, and less often a reaction to a drug or transfusion | Tell the nurse or surgeon. Report it right away if you have breathing problems, a racing heart or confusion. |
| Days 1–3 | Usually non-infectious causes, including the lungs not fully expanding | Tell the team the same day. Do the breathing exercises and walking you were given. |
| After day 3 | Infection becomes more likely. The review says fever after about 96 hours leans infectious, and fever lasting past days 4–5 warrants investigation. | Contact the surgeon the same day and expect to be examined. |
The review also notes that a deep surgical site infection typically shows up from around day four. It brings higher fever along with wound pain, redness, warmth and sometimes pus. If you have a wound concern rather than a fever question, our guide to wound separation after plastic surgery covers how an opening wound is triaged.
The causes that are not about the wound
Patients tend to assume any fever means an infected incision. Clinicians run through a wider list, and some of the items are urgent:
- Lungs. Shallow breathing because of pain, a tight garment or abdominal tightening after a tummy tuck can leave parts of the lung under-inflated. StatPearls notes this commonly appears 24 to 72 hours after major surgery, sometimes with a mild cough and slight breathlessness.
- Blood clots. StatPearls lists deep vein thrombosis and pulmonary embolism among non-infectious causes of fever. The American Society of Plastic Surgeons' tummy tuck safety page lists deep vein thrombosis and heart and lung complications among the risks of that operation. A fever with calf swelling, chest pain or shortness of breath is an emergency.
- Urinary infection. StatPearls links post-operative urinary infection mainly to urinary catheters. If you had one, mention burning or frequent urination.
- Medications. A drug fever can begin within 24 to 48 hours of starting a new medicine, antibiotics included.
How to measure it so the number means something
Colombian thermometers and clinic staff use Celsius. Know the conversions before you need them:
| Celsius | Fahrenheit |
|---|---|
| 37.5 °C | 99.5 °F |
| 38.0 °C | 100.4 °F |
| 38.6 °C | 101.5 °F |
| 39.0 °C | 102.2 °F |
- Pack your own digital thermometer and use the same one every time.
- Write down the time, the reading and any medicine taken in the previous few hours. Fever-reducing painkillers such as acetaminophen (paracetamol, often sold in Colombia as acetaminofén) can bring the number down and hide the trend.
- Don't take a reading straight after a hot drink, a shower or a long spell under blankets and compression.
- Record what else is going on: wound appearance, drain output and its colour if you have drains, pain level, breathing, appetite and urination.
A message that says "38.3 at 14:00, two hours after acetaminophen, left side of abdomen redder and more painful since this morning" gets a much better response than "I feel hot."
A simple escalation plan
Agree on this with your surgeon before surgery, and make sure your companion or recovery-house staff know it.
Go to emergency care now
- Shortness of breath, chest pain or coughing up blood.
- Confusion, extreme drowsiness, fainting or a racing heartbeat.
- Fever with rapidly spreading redness, or a wound that is dark or very painful.
- A painful, swollen calf or leg together with fever or breathing symptoms.
Call the surgeon the same day
- Any fever starting after day three.
- A fever that keeps rising, or that returns once acetaminophen wears off.
- A fever with increasing wound redness, warmth, swelling, pus or a bad smell.
- Cloudy or foul-smelling drain fluid, or burning when you urinate.
Mention it at your next check, and keep logging
- A low-grade reading in the first two days that is steady or falling, while you otherwise feel as expected.
Before surgery, find out which hospital your surgeon uses for complications and save its address. Ask too who answers the after-hours number. A recovery house can take your temperature and help you message the clinic, but it cannot examine your lungs or order blood tests. Our recovery houses guide explains what those services usually include.
What an evaluation usually involves
If your surgeon asks you to come in, it helps to know what to expect, so the visit doesn't feel like an overreaction. The StatPearls review describes a structured workup that starts with an examination and checks of breathing, oxygen levels and circulation. Depending on what the examination suggests, it may then include:
- Blood tests such as a blood count and inflammation markers.
- Blood cultures, ideally taken before antibiotics are started.
- Urine tests, or a culture of wound or drain fluid.
- Imaging: a chest X-ray, an ultrasound or CT scan, or a Doppler ultrasound of a swollen leg to look for a clot.
Not every patient needs all of these, and the order depends on the findings. The point is that working out a fever usually takes tests a recovery house can't do. Starting antibiotics "just in case" over WhatsApp is not the same as finding the cause.
Set it up before surgery day
Fever-ready checklist
- A digital thermometer of your own, and the Celsius conversions saved on your phone.
- A one-page log: time, temperature, medicines taken, wound, drains, breathing, pain.
- The surgeon's after-hours number, and who actually answers it.
- The name and address of the hospital your surgeon uses for complications.
- A companion or recovery-house contact who knows the emergency signs above.
- Your medication schedule written out, so fever-reducing doses are easy to see.
Fever and your flight home
An unexplained fever is a reason to tell your surgeon before you travel, not to stay quiet so you can keep your booking. A long flight adds immobility to whatever is causing the fever, and you would be leaving the team that knows your operation. If your surgeon wants to examine you, go, even if checkout is in the morning. Our article on when you can fly after plastic surgery covers the wider clearance question.
If a fever begins after you get home, contact your surgeon and also see a doctor locally. Remote advice can't take blood, listen to your chest or scan your leg. Bring your operative report and discharge medication list.
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Message on WhatsAppFrequently asked questions
Is 38 °C a fever after surgery?
38.0 °C is 100.4 °F, a commonly used fever threshold. The StatPearls review notes that low-grade readings up to about 38.6 °C in the first 48–72 hours are often considered normal after routine surgery. Report any reading to your team so they can interpret it.
Can I just take acetaminophen and wait?
Take only what your surgeon prescribed. Remember that it can lower the number without fixing the cause. Note the time of each dose so your team can read the trend correctly.
Is a fever on day one usually an infection?
Usually not. According to StatPearls, fever in the first 48–72 hours is most often caused by non-infectious factors. Infection becomes more likely from around day four.
Should I call my surgeon or go to the hospital?
For breathing problems, chest pain, confusion, fainting or a rapidly worsening wound, go to emergency care. For other fevers, especially new ones after day three, call the surgeon the same day.
What if the fever starts after I fly home?
Contact your surgeon and see a local doctor promptly. Bring your operative report and medication list so they can assess you quickly.