A sudden, noticeable lump on the head following a minor collision or fall is a common result of a head injury. This bump, often called a “knot” or “goose egg,” is a subgaleal hematoma. It represents localized swelling and bruising when blood vessels beneath the scalp are ruptured by blunt force trauma. While alarming, most head bumps are minor and resolve with simple home care, though any head injury requires caution.
Understanding What Causes the Bump
The appearance of a knot on the head results from damage to the blood vessels in the scalp tissue. The scalp is highly vascular, containing a dense network of small arteries and veins that break easily when compressed against the skull. When these vessels tear, blood leaks into the surrounding tissue layers, forming a collection of pooled blood known as a hematoma.
The bump becomes distinct and firm due to the specific anatomy of the head. The space just under the galea aponeurotica—a dense, fibrous layer—is a loose connective tissue layer. This allows the released blood to quickly accumulate. Since the swelling cannot easily spread outward beyond the skull, the blood is forced to protrude, creating the characteristic dome or egg shape.
Immediate First Aid Treatment at Home
Immediate care for a head bump focuses on reducing blood flow to limit the size of the hematoma and control swelling. Cold compression is the most effective first aid method. Apply a cold pack or ice wrapped in a thin towel directly to the bump immediately after the injury occurs.
The cold temperature causes vasoconstriction, narrowing the blood vessels and slowing internal bleeding. Keep the cold pack on the area for 10 to 20 minutes, then remove it for 30 minutes to allow the skin temperature to normalize before reapplying. This cycle can be repeated for the first 24 to 48 hours to manage swelling and pain.
Rest is necessary immediately following a head injury. For pain relief, acetaminophen is the preferred over-the-counter medication. Avoid using NSAIDs like ibuprofen or aspirin in the initial hours, as these medications can interfere with blood clotting and potentially increase bruising.
Critical Symptoms Requiring Emergency Care
While most head bumps are harmless, certain signs and symptoms indicate that the injury may be more severe and require immediate medical attention. Any loss of consciousness, even for a brief moment, necessitates an emergency room visit. A headache that becomes progressively worse over time or is unusually severe is a red flag that could signal increased pressure inside the skull.
Repeated vomiting or persistent nausea following the injury may be a sign of a concussion or more serious complication. Changes in mental status, such as confusion, slurred speech, sudden dizziness, or difficulty with balance, also warrant urgent medical evaluation. The injured person should be monitored closely for any changes in behavior, such as unusual irritability, excessive drowsiness, or difficulty waking up.
Unequal pupil sizes, where one pupil is noticeably larger than the other, is a sign of pressure on the brain. Other urgent symptoms include seizures, clear fluid or blood draining from the ears or nose, or any weakness or numbness in the limbs. If any of these symptoms appear during the 24 to 48 hours following the head bump, seek immediate emergency care, as they may indicate an intracranial hematoma or another serious traumatic brain injury.
Expected Healing Timeline and Resolution
The process of a head knot resolving follows a timeline as the body works to reabsorb the pooled blood. Swelling from a simple hematoma typically reaches its maximum size within the first 24 to 48 hours after the injury. After this initial peak, the lump will begin to gradually soften and decrease in size as the body breaks down the trapped blood cells.
The appearance of the overlying skin will change as the hematoma resolves, a process known as bruising. The area may transition through colors, starting from a reddish-purple, then shifting to blue or black, and finally turning shades of green and yellow before fading completely. This color progression reflects the breakdown and reabsorption of hemoglobin from the pooled blood.
Most small, superficial head knots will resolve completely within one to two weeks with home care. If the lump persists beyond two weeks, or if it changes in size, texture, or causes increasing pain, consult a healthcare provider. A persistent lump may require professional examination to ensure the underlying cause is not complex.