Can you get a fever from an injury?

September 22, 2025 •

4 min read

An injury triggers a complex response from your body's immune system, which can result in a rise in temperature as part of the healing process. However, a fever after an injury can signal a normal inflammatory reaction or a more serious underlying issue like an infection or internal trauma. Understanding can you get a fever from an injury is crucial for knowing when to monitor your symptoms and when to seek immediate medical attention.

Quick Summary

An injury can cause a fever, which is the body's natural inflammatory reaction to trauma, a defense mechanism against an infection, or a sign of a more serious internal issue. A high or persistent fever, especially if accompanied by other concerning symptoms, should prompt immediate medical evaluation. The timing and severity of the fever can offer clues about its cause and importance.

Key Points

Inflammatory Response: Your body's immediate reaction to trauma releases cytokines, which can trigger a mild, short-term fever.
Infection Risk: Fevers developing days after an injury are often a sign of an infection, especially if accompanied by worsening pain, swelling, or pus.
Brain Injury: A traumatic brain injury can disrupt the brain's temperature regulation, leading to a fever that requires medical attention.
Internal Damage: Fever can be a subtle warning sign of hidden internal injuries, bleeding, or blood clots that may not have obvious external symptoms.
When to Act: High or persistent fevers, along with worrying symptoms like confusion or spreading redness, indicate a need for immediate medical care.
Professional Diagnosis: Medical professionals can use physical exams, lab tests, and imaging to pinpoint the specific cause of a post-injury fever.

The Body's Inflammatory Response to Trauma

When you sustain an injury, whether a minor cut or a significant trauma, your body's immune system activates a protective process called inflammation. This is the first step in healing and involves a cascade of cellular and chemical reactions.

The Role of Cytokines

During this process, damaged cells release signaling molecules known as cytokines into the bloodstream. These pyrogenic (fever-inducing) substances act on the hypothalamus, the brain's temperature-regulating center, to increase the body's temperature. This elevation can help the immune system function more effectively by enhancing white blood cell activity and potentially inhibiting the growth of certain pathogens.

Acute Inflammation: This is the immediate, short-term response to injury. You may experience localized symptoms like heat, swelling, and redness, in addition to a mild, systemic fever.
Systemic Inflammatory Response Syndrome (SIRS): In cases of severe trauma, the inflammatory response can become widespread, affecting the entire body. This can lead to a significant and potentially dangerous fever.

Infection as a Cause of Post-Injury Fever

One of the most concerning causes of a fever after an injury is an infection. This can happen in several ways:

Wound Infection: Any break in the skin, such as a cut or scrape, can allow bacteria to enter. If the wound is not cleaned and cared for properly, an infection can take hold. Symptoms like increasing redness, swelling, warmth, and pus can accompany the fever.
Internal Infections: After a severe injury or surgery, internal wounds or damaged tissue can become infected. This may not be immediately obvious from the outside, and a fever could be one of the only early signs.
Sepsis: If an infection spreads to the bloodstream, it can lead to sepsis, a life-threatening medical emergency. This condition is often marked by a high fever, chills, rapid breathing, and confusion.

Specific Injuries and Their Link to Fever

Different types of injuries carry different risks for causing a fever:

Traumatic Brain Injuries (TBI)

Head trauma can directly affect the brain's ability to regulate body temperature. A concussion or more severe TBI can cause a neurogenic fever, which is directly related to the brain injury itself. Fever is a common symptom in patients with TBI, and its presence can sometimes be associated with the severity of the injury.

Internal Injuries and Blood Clots

Blunt force trauma from an accident, such as a car crash or a fall, can damage internal organs or blood vessels, even without visible external wounds. This damage can cause internal bleeding or clots, which trigger a systemic inflammatory response and can lead to a fever.

Post-Surgical Fever

Following surgery, it is common to experience a mild, low-grade fever within the first 48 hours. This is typically due to the body's inflammatory response to the trauma of the procedure. However, a fever that is high or persists for several days may indicate an emerging infection at the surgical site or another complication.

Comparison: Inflammatory vs. Infectious Fever

Understanding the potential source of your fever is important. Here is a simplified comparison:


Feature	Inflammatory (Trauma Response) Fever	Infectious Fever
Timing	Often begins within hours of the injury or surgery.	Typically develops later, often 24 hours to several days after the injury.
Severity	Usually mild to moderate and may resolve quickly.	Can be mild or high and may persist or worsen over time.
Duration	Short-lived, often resolving within 48 hours.	Longer lasting, may get progressively worse.
Accompanying Symptoms	Localized pain, swelling, and redness around the injury site.	Signs of wound infection, chills, body aches, confusion, or increased pain.
Underlying Cause	The body's immune system reacting to tissue damage.	Pathogens (bacteria or viruses) invading the body.

When a Post-Injury Fever Requires Medical Attention

While some fevers are a normal part of healing, you should always be cautious. A fever can be a warning sign of a dangerous underlying problem. You should seek immediate medical attention if you experience any of the following:

A high fever: For adults, a temperature of 103°F (39.4°C) or higher requires immediate evaluation.
Persistent fever: If a fever lasts for more than 48 hours or worsens, it's a cause for concern.
Worsening symptoms: If you notice that your pain, swelling, or redness is increasing after the initial 48 hours, see a doctor.
Signs of infection: Any discharge (especially if foul-smelling), pus, or red streaks extending from a wound should be promptly assessed.
Neurological symptoms: Confusion, dizziness, severe headache, or an altered mental state combined with a fever could indicate a serious issue.
Signs of sepsis: Chills, rapid heart rate, low blood pressure, and confusion are all signs of a systemic infection that needs immediate emergency care.

How a Medical Professional Diagnoses the Cause

To determine the cause of a post-injury fever, a doctor will conduct a comprehensive evaluation. This may include:

Physical examination: Checking vital signs, assessing the injury site, and reviewing overall health.
Imaging studies: X-rays, CT scans, or MRIs to look for internal injuries, fractures, or bleeding.
Laboratory tests: Blood tests, including a complete blood count (CBC) to check for signs of infection or inflammation, and blood cultures if a bacterial infection is suspected.

Conclusion

A fever after an injury is not always a sign of a dire emergency, but it is a signal from your body that should never be ignored. It can indicate a natural healing process or a more serious underlying problem like an infection, internal bleeding, or brain trauma. The key is to be vigilant and aware of your symptoms. By paying close attention to the severity, duration, and accompanying signs of your fever, you can make an informed decision about when to seek professional medical advice. For more information on the immune response, you can consult reliable sources like the Cleveland Clinic's breakdown of inflammation.

Frequently Asked Questions

A fever can start within hours of an injury as part of the initial inflammatory response, or it may develop days later, particularly if an infection is brewing.

No, a mild, low-grade fever in the first 48 hours after an injury or surgery is often a normal part of the body's inflammatory healing process. However, any persistent or high fever should be medically evaluated.

Yes, a concussion or other traumatic brain injury (TBI) can cause a fever by damaging the area of the brain that controls body temperature. This is known as a neurogenic fever.

Seek medical attention immediately if your fever is very high ($>103°F$), if it persists or worsens, or if it is accompanied by other serious symptoms like confusion, difficulty breathing, or signs of an infection around a wound.

Common signs of an infected wound include increasing redness, swelling, warmth, pain, pus, foul odor, and red streaks spreading away from the wound site.

In some cases, yes. The body's natural shock and adrenaline response can mask pain, making a fever one of the few initial clues that there is a hidden internal injury or infection.

Fevers can result from a wide range of injuries, including significant blunt force trauma, surgical procedures, bone fractures, deep tissue damage, and traumatic brain injuries.

Mild fevers can often be managed with rest, hydration, and staying cool, but you should always consult a doctor before using over-the-counter fever reducers, especially after a significant injury, to ensure you don't mask a more serious issue.