Intracranial Hematoma: The Head Injury That Can Turn Dangerous Weeks Later
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is an intracranial hematoma and why is it dangerous?
An intracranial hematoma is a collection of blood within the skull that presses on the brain, most often after a head injury, though symptoms may not appear for days, weeks or months. Warning signs include worsening headache, vomiting, confusion, slurred speech and drowsiness. Because it can be life-threatening, it usually requires immediate emergency treatment, which may include surgery.
What the research says
A drain left in place after burr-hole surgery cut the chance of a chronic subdural hematoma coming back. In a randomized trial of adults having burr-hole drainage of a chronic subdural hematoma (108 assigned a drain, 107 no drain), the hematoma recurred and needed redrainage in 9.3% of patients with a drain versus 24% without, and deaths at 6 months were 8.6% versus 18.1% (Santarius et al., Lancet, 2009 [2]).
Steroid tablets reduced repeat surgery but led to worse overall recovery. In a UK trial of 748 adults with symptomatic chronic subdural hematoma (mean age 74; 94% had surgery), a favorable outcome at 6 months was reported in 83.9% of those given a 2-week course of dexamethasone versus 90.3% given placebo; repeat surgery for recurrence was less common with dexamethasone (1.7% vs 7.1%), but adverse events were more frequent (Hutchinson et al., New England Journal of Medicine, 2020 [3]).
What is an intracranial hematoma?
An intracranial hematoma is a collection of blood within the skull. The blood may collect in the brain tissue itself or underneath the skull, where it presses on the brain.
It is usually caused by a blood vessel that bursts in the brain. It can also result from a head injury, such as one from a car accident or a fall.
Some head injuries that cause only a short period of unconsciousness turn out to be minor. An intracranial hematoma is different. It is potentially life-threatening and usually requires immediate treatment, which might include surgery to remove the blood.
The 8 symptoms of an intracranial hematoma
Symptoms may develop right after a head injury, or they may take weeks or longer to appear. There can be a period of time without any symptoms after the injury. This symptom-free window is called the lucid interval.
Over time, pressure on the brain increases and produces some or all of the following symptoms:
Symptom | What it looks like |
Worsening headache | A headache that keeps getting worse |
Vomiting | Repeatedly throwing up |
Drowsiness | Progressive sleepiness and gradual loss of consciousness |
Dizziness | Feeling unsteady or off-balance |
Confusion | Trouble thinking clearly |
Unequal pupils | Pupils that are different sizes |
Slurred speech | Speech that becomes unclear |
Paralysis | Loss of movement on the opposite side of the body from the head injury |
As more blood fills the brain or the narrow space between the brain and the skull, additional symptoms may appear, including feeling very sleepy or sluggish, seizures, and loss of consciousness.
A critical feature of intracranial hematomas is the lucid interval: a period after a head injury when someone seems fine, followed by worsening pressure on the brain that produces symptoms hours, days, or weeks later.
The 3 types of intracranial hematoma
The location of the bleeding determines the type of hematoma and how it behaves. There are three categories.
Type | Where the blood collects | Typical behavior |
Subdural hematoma | Between the brain and the dura mater, the outermost protective layer | Can be acute, subacute, or chronic; bleeding may be slow and appear weeks or months later |
Epidural hematoma (extradural) | Between the outer surface of the dura mater and the skull | Often drowsiness or coma from the moment of injury; one affecting an artery can be deadly without prompt treatment |
Intracerebral (intraparenchymal) hematoma | Inside the brain tissue itself | Many causes beyond injury, including aneurysm, high blood pressure, and tumors |
Subdural hematoma
A subdural hematoma occurs when blood vessels burst between the brain and the outermost of three protective layers that cover the brain, the dura mater. The leaking blood forms a hematoma that presses on brain tissue. A hematoma that keeps growing can cause gradual loss of consciousness and possibly death.
Subdural hematomas come in three forms, all of which require medical attention as soon as symptoms appear. Prompt medical care may prevent permanent brain damage.
Form | How it develops |
Acute | The most dangerous type; generally caused by a bad head injury, and symptoms usually appear immediately |
Subacute | Symptoms take time to develop, sometimes days or weeks after a head injury |
Chronic | The result of less severe head injuries; causes slow bleeding, and symptoms can take weeks or even months to appear |
With chronic subdural hematomas, you might not remember hurting your head. For example, bumping your head while getting into the car can cause bleeding, especially if you are on a blood-thinning medicine.
Epidural hematoma
An epidural hematoma occurs when a blood vessel bursts between the outer surface of the dura mater and the skull. Blood then leaks between the dura mater and the skull to form a mass that presses on brain tissue. The most common cause is a head injury. This type is also called an extradural hematoma.
Some people with an epidural hematoma remain conscious. But most become drowsy or go into a coma from the moment of injury. An epidural hematoma that affects an artery in the brain can be deadly without prompt treatment.
Intracerebral hematoma
An intracerebral hematoma occurs when blood pools in the tissues of the brain. It is also called an intraparenchymal hematoma, and it has many causes.
Cause | How it leads to bleeding |
Head injury | Can result in multiple intracerebral hematomas |
Ruptured aneurysm | A bulging blood vessel breaks open |
Poorly connected arteries and veins | A condition present from birth |
High blood pressure | Strains the blood vessels in the brain |
Tumors | Can bleed into brain tissue |
Certain diseases | Some diseases cause sudden leakage of blood into the brain |
What increases your risk
Activities that raise the risk of a serious head injury, such as riding a motorcycle or bicycle without a helmet, also raise the risk of an intracranial hematoma.
Risk factor | Why it matters |
Increasing age | The risk of a subdural hematoma increases with age |
Daily blood thinners | Taking aspirin or another blood-thinning medicine daily increases risk |
Alcohol use disorder | Raises the risk of a subdural hematoma |
Poorly connected brain blood vessels from birth | Increases the risk of an intracerebral hematoma |
Brain aneurysm | A bulging blood vessel in the brain increases risk |
High blood pressure | Increases the risk of an intracerebral hematoma |
Brain tumors | Can cause intracerebral bleeding |
If you are an older adult, even mild head trauma can cause a hematoma. This is especially true if you are taking a blood-thinning medicine or an anti-platelet medicine, such as aspirin. Importantly, a head injury can cause an intracranial hematoma even if there is no open wound, bruise, or other obvious damage.
When to seek emergency care
An intracranial hematoma can be life-threatening and needs emergency treatment.
Seek immediate medical attention after a blow to the head if you or someone you know experiences loss of consciousness, a headache that does not go away, or vomiting, weakness, blurred vision, or trouble staying steady.
If you do not notice symptoms right after a hit to the head, watch for physical, mental, and emotional changes in the days that follow. For example, if someone seems fine after a head injury and can talk but later becomes unconscious, seek immediate medical care.
Even if you feel fine, ask someone to watch you. Memory loss after a blow to your head can make you forget about the blow. Someone you tell is more likely to recognize the warning signs and get you medical attention.
How an intracranial hematoma is diagnosed
Diagnosing an intracranial hematoma can be a challenge because people with a head injury may seem fine at first. Healthcare professionals usually assume that bleeding inside the skull is the cause of a loss of consciousness after a head injury until proved otherwise.
Imaging techniques are the best ways to determine the position and size of a hematoma.
Test | How it works |
CT scan | A sophisticated X-ray machine linked to a computer produces detailed images of the brain; you lie on a movable table guided into a large doughnut-shaped machine. It is the most commonly used imaging scan to diagnose intracranial hematomas |
MRI scan | A magnetic field and radio waves make computerized images; you lie on a movable table guided into a tube |
Angiogram | If there is concern about a possible aneurysm or other blood vessel issue, this test uses X-rays and a special dye to produce pictures of blood flow in the brain's blood vessels |
Treatment: from monitoring to surgery
Intracranial hematomas that are small and produce no symptoms do not need to be removed. However, symptoms can appear or worsen days or weeks after the injury. As a result, you might have to be watched for neurological changes, have your intracranial pressure monitored, and undergo repeated head CT scans.
If you take blood-thinning medicine, such as warfarin (Jantoven), you may need therapy to reverse the effects of the medicine and reduce the risk of further bleeding. Options for reversing blood thinners include giving vitamin K and fresh frozen plasma.
Surgical options
Intracranial hematoma treatment often involves surgery. The type of surgery depends on the type of hematoma.
Surgical option | When it is used |
Surgical drainage | Used if the blood is in one area and has changed from a solid clot to a liquid; a small hole is created in the skull and suction removes the liquid |
Craniotomy (removing part of the skull) | Used for large hematomas; a section of the skull is opened to remove the blood |
Recovery
Recovery after an intracranial hematoma can take a long time, and you might not recover completely. The greatest recovery happens up to six months after the injury, usually with lesser improvement after that. If you continue to have neurological symptoms after treatment, you might need occupational and physical therapy.
Coping and support during recovery
Patience is important for coping with brain injuries. The majority of recovery for adults happens during the first six months. Then you might see smaller, more-gradual improvements for up to two years after the hematoma.
Recovery step | What it involves |
Get enough sleep | Sleep at night and rest in the daytime when you feel tired |
Ease back into activities | Return to typical activities gradually as you feel stronger |
Avoid contact sports | Do not participate in contact and recreational sports until your doctor says it is OK |
Check before driving or operating machinery | Your reaction times will likely have slowed; check with your healthcare team before driving, playing sports, riding a bicycle, or operating heavy machinery |
Check before taking medicine | Ask your healthcare team before taking any medicine |
Avoid alcohol | Do not drink alcohol until you have recovered fully; alcohol may slow recovery and too much increases the risk of a second injury |
Keep memory notes | Write down things you have trouble recalling |
Share important decisions | Talk with someone you trust before making important decisions |
Preventing a head injury in the first place
To prevent or minimize a head injury that may cause an intracranial hematoma, three habits stand out.
Wear a helmet and make sure your kids wear helmets too. Wear an appropriate and properly fitted helmet during any activity that could result in head injury. This includes contact sports, bicycling, motorcycling, skiing, horseback riding, skating, skateboarding, and snowboarding.
Buckle your seat belt and make sure your kids are buckled in every time you drive or ride in a motor vehicle.
Protect young children. Always use properly fitted car seats. Pad countertops and edges of tables, block stairways, and attach heavy furniture or appliances to the wall to prevent tipping. Keep children from climbing on objects that are not safe or steady. Place safety gates on stairs and guards on windows.
Conclusion: A head injury is not always "just a bump"
An intracranial hematoma is one of the most dangerous possible outcomes of a head injury, precisely because it can hide behind a symptom-free period. The bleeding presses on the brain, symptoms can build for days or weeks, and the condition usually requires immediate emergency treatment. The practical takeaway is simple: take any significant blow to the head seriously, know the warning signs, have someone watch you afterward, and seek emergency care if a worsening headache, vomiting, confusion, slurred speech, or drowsiness appears.
If you or someone you know has a head injury with any warning signs, call emergency services now — do not wait to see if symptoms improve.
Frequently asked questions
1. What is an intracranial hematoma?
An intracranial hematoma is a collection of blood within the skull, usually from a blood vessel that bursts in the brain or from a head injury. The blood presses on the brain and can be life-threatening, usually requiring immediate treatment.
2. What causes an intracranial hematoma?
The most common cause is a head injury from motor vehicle or bicycle accidents, falls, assaults, or sports injuries. In older adults, even mild head trauma can cause one, especially when taking blood-thinning medicine such as aspirin.
3. Can a hematoma appear weeks after a head injury?
Yes. Symptoms may take weeks or longer to appear, and a symptom-free "lucid interval" is common. Chronic subdural hematomas can take weeks or even months to cause symptoms, sometimes from a minor bump you do not remember.
4. What are the warning signs of a brain bleed after a head injury?
Warning signs include a worsening headache, vomiting, drowsiness, dizziness, confusion, unequal pupils, slurred speech, and weakness on the opposite side of the body from the injury, along with possible seizures and loss of consciousness.
5. Should I see a doctor after hitting my head if I feel fine?
Seek emergency care after a blow to the head if there is loss of consciousness, a persistent headache, or vomiting, weakness, blurred vision, or trouble staying steady. Even if you feel fine, ask someone to watch you for physical, mental, and emotional changes.
6. What are the three types of intracranial hematoma?
The three types are subdural (between the brain and the dura mater), epidural or extradural (between the dura mater and the skull), and intracerebral or intraparenchymal (inside the brain tissue).
7. How is an intracranial hematoma diagnosed?
Through imaging tests: a CT scan (the most commonly used), an MRI scan, or an angiogram if an aneurysm or blood vessel problem is suspected.
8. Does every intracranial hematoma need surgery?
No. Small hematomas that produce no symptoms do not need to be removed but are monitored with neurological checks, pressure monitoring, and repeated head CT scans. Surgery, such as drainage or a craniotomy, is used when the hematoma is large or causing symptoms.
9. How long does recovery take after an intracranial hematoma?
Recovery can take a long time and may not be complete. The greatest recovery happens within six months of the injury, with smaller improvements possible for up to two years.
10. How can I prevent an intracranial hematoma?
Prevent head injuries by wearing a properly fitted helmet during risky activities, buckling your seat belt every time you drive, and childproofing your home with car seats, padding, safety gates, and secured furniture.
Further Reading
Brain Aneurysm Foundation. Home. Brain Aneurysm Foundation. Accessed October 30, 2026. https://www.bafound.org/ — patient resources on brain blood vessel problems
American Association of Neurological Surgeons. Traumatic Brain Injury. AANS. Accessed October 30, 2026. https://www.aans.org/patients/conditions-treatments/traumatic-brain-injury/ — neurosurgical guidance on traumatic brain injury and its complications
Sources
Mayo Clinic Staff. Intracranial hematoma - Symptoms and causes. Mayo Clinic. June 8, 2024. https://www.mayoclinic.org/diseases-conditions/intracranial-hematoma/symptoms-causes/syc-20356145
Santarius T, Kirkpatrick PJ, Ganesan D, et al. Use of drains versus no drains after burr-hole evacuation of chronic subdural haematoma: a randomised controlled trial. Lancet. 2009;374(9695):1067-1073. PMID 19782872. https://doi.org/10.1016/S0140-6736(09)61115-6
Hutchinson PJ, Edlmann E, Bulters D, et al. Trial of dexamethasone for chronic subdural hematoma. New England Journal of Medicine. 2020;383(27):2616-2627. PMID 33326713. https://doi.org/10.1056/NEJMoa2020473
Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read here.
Comments