A nosebleed following a blow to the head is a common and alarming occurrence that often raises concerns about a concussion. While concussions are frequently associated with head impacts that also cause nosebleeds, the functional brain injury itself does not cause the bleeding. The nosebleed is almost always a result of direct physical trauma to the structures of the face, nose, or skull that happened simultaneously with the force that caused the concussion. Understanding the distinct nature of a concussion compared to a structural injury is necessary to properly evaluate the seriousness of the event.
Concussion is a Functional Injury, Not a Structural One
A concussion is classified as a mild traumatic brain injury (mTBI) that results from a biomechanical force transmitted to the head, causing a temporary disruption of neurological function. The injury is largely considered a functional one, meaning it alters how the brain works rather than causing gross physical damage that would be visible on standard medical imaging like a CT scan or MRI. This functional change involves a cascade of events at the cellular level, disrupting the brain’s neurochemical balance and energy metabolism.
Because a concussion is a functional injury, it does not involve the physical tearing of tissue or blood vessels within the brain that would lead to external bleeding from the nose or ears. The symptoms of a concussion—such as headache, confusion, dizziness, and memory problems—reflect this temporary disruption of brain processes.
A person can sustain a concussion and a structural injury, like a broken nose, from the same impact, which is why the two symptoms are often mistakenly linked. The force required to cause the brain to accelerate and decelerate suddenly inside the skull is often enough to also injure nearby facial structures. This distinction is important because the presence of a nosebleed points to a different set of physical damage that requires its own assessment.
Structural Causes of Nosebleeds Following Head Impact
The most common cause of a nosebleed after head trauma is direct impact to the face or nose, which is rich in small, fragile blood vessels. The nasal septum, the wall dividing the nostrils, contains a dense network of vessels close to the surface, making them highly susceptible to rupture even from a seemingly minor blow. When the face absorbs the impact, these vessels tear, leading to an anterior nosebleed that is usually easy to control with direct pressure.
More forceful trauma can result in nasal bone or septal fractures, where the broken bone fragments can lacerate the surrounding tissue and blood vessels, leading to heavier bleeding. Additionally, the impact can cause a septal hematoma, a collection of blood under the lining of the septum, which can sometimes bleed externally. In rare instances of severe force, trauma can fracture the bones at the base of the skull, which may cause a posterior nosebleed that originates deeper in the nasal cavity and is more difficult to manage.
Warning Signs Requiring Immediate Care
While many nosebleeds after a head injury are due to localized facial trauma, certain signs indicate a serious injury, such as a skull fracture or traumatic brain injury (TBI), which require immediate emergency medical attention. The most serious warning sign is the appearance of clear or watery fluid mixed with blood coming from the nose or ear. This fluid may be cerebrospinal fluid (CSF), the clear liquid that cushions the brain and spinal cord, suggesting a basilar skull fracture has created a tear in the protective barrier surrounding the brain.
A CSF leak is a serious condition because it provides an open pathway for bacteria to travel from the nasal cavity to the brain, significantly increasing the risk of meningitis. Other red flag symptoms include bruising around the eyes that appears without a direct injury to the eyes, known as “raccoon eyes,” or bruising behind the ears, called Battle’s sign. Both of these are strong indicators of a fracture to the base of the skull.
An immediate emergency evaluation is necessary if a nosebleed persists and cannot be stopped after 20 to 30 minutes of continuous pressure, or if it is accompanied by other severe symptoms:
- Severe, worsening headache or repeated vomiting.
- Any change in consciousness or alertness, including loss of consciousness.
- New problems with vision or speech.
- The onset of seizure activity following the impact.