A bump after you knock your head is usually the body’s normal reaction, not a sign of damage underneath. Lumps that show up with no injury at all are most often harmless cysts or growths in the skin or bone. A big bump doesn’t mean a worse injury: the danger of a head injury shows in how the person acts and feels, not in the size of the swelling.
Why Your Head Swells So Fast After a Knock
The scalp has five layers, and the one just under the skin is packed with blood vessels and nerves.1TeachMeAnatomy. The Scalp – Layers – Innervation – Blood Supply – TeachMeAnatomy Those vessels are stuck tightly to the surrounding tissue, so when they tear they can’t tighten and close off.2TeachMeAnatomy. The Scalp – Layers – Innervation – Blood Supply – TeachMeAnatomy That’s why the scalp bleeds heavily and swells fast, even from a minor blow.3The Common Vein. Scalp Hematoma with Active Extravasation
A goose egg is the name for that rounded lump. It rises within minutes and can be surprisingly large and firm. It’s tender to touch, but the pain stays at the bump itself. The skin around it may look red, then bruise over the next days. It stays in one spot rather than drifting or spreading.
The scalp sits directly over bone, so swollen tissue has nowhere to go inward and is pushed out into a lump. The tight fibrous layer under the skin holds the pooling blood in a small area, which is why the lump feels firm and well defined. Later it often turns softer and squishier as the blood inside slowly breaks down.
Most goose eggs are a contained pocket of blood and fluid just under the skin. But if blood gets into a deeper, loose layer above the skull, it can spread across the whole top of the head, from the brow to the back of the neck.4The Common Vein. Scalp Hematoma with Active Extravasation Swelling that keeps widening across the head, rather than staying a firm round lump, needs a doctor that day. A blow with no visible swelling can still injure the brain, so behaviour and symptoms over the next day are what to watch.
Warning Signs That Need Emergency Care
Go to the ER or call 911 after a head injury if any of these appear:
- Passing out, even briefly, or not remembering the injury
- A headache that gets steadily worse
- Vomiting more than once
- Confusion, unusual sleepiness, or being hard to wake
- Slurred speech, weakness or numbness on one side, or trouble walking
- A seizure, or one pupil larger than the other
A broken skull base has its own signs. Clear fluid dripping from the nose or ears, blood behind the eardrum, bruising behind the ear, and bruising around both eyes can all point to a fracture at the base of the skull.5Neurology perspectives. Raccoon sign Bruising around both eyes usually appears 2 to 3 days after the injury.6Neurology perspectives. Raccoon sign A CT scan is what confirms a fracture.7PubMed Central. Analysis and Clinical Importance of Skull Base Fractures in Adult Patients with Traumatic Brain Injury
Most danger signs appear in the first 24 to 48 hours, but they can appear later. Have someone stay with the injured person that first night. Sleeping is fine if they are acting like themselves, but wake them to check that they respond normally. If any sign on the list appears later, even days later, return to care.
At the ER, staff ask how the injury happened and check alertness, pupils and strength. They also ask about blood thinners and age. Taking blood thinners or being over 65 lowers the bar for getting checked after any real blow.
You may be sent home without a scan, and that’s a sound decision. Emergency doctors use checklists of symptoms and risk factors to decide who needs a CT scan, and the best of these catch every injury that needs surgery.8PubMed. External validation of the Canadian CT Head Rule and the New Orleans Criteria for CT scanning in patients with minor head injury The strictest rules send nearly everyone to scanning, so many hospitals use rules that spare more than a third of patients a scan.9PubMed. External validation of the Canadian CT Head Rule and the New Orleans Criteria for CT scanning in patients with minor head injury
How to Treat a Goose Egg at Home
Hold an ice pack wrapped in a cloth on the bump for 15 to 20 minutes.10Indigo. What to Do When You Hit Your Head Then take it off for 30 minutes to an hour, and repeat several times a day for the first day or two.11UPMC | Life Changing Medicine. How to Treat a Bump to the Head | UPMC HealthBeat A small goose egg may only need icing once.12UPMC | Life Changing Medicine. How to Treat a Bump to the Head | UPMC HealthBeat
A bag of frozen peas or a gel pack wrapped in a thin towel molds to the curve of the head better than loose ice cubes. Press lightly, and check the skin after each round; if it looks white, waxy, or numb, stop and let it warm up before icing again.
Some common habits don’t help. Pressing or rubbing the lump doesn’t speed healing, and trying to drain it with a needle risks infection. For pain, plain acetaminophen is a common choice; ask a doctor before taking ibuprofen if bleeding is a concern.
Swelling usually starts going down within a few hours.13Indigo. What to Do When You Hit Your Head A large goose egg can take up to a week to fully go away.14Indigo. What to Do When You Hit Your Head Along the way the lump softens and flattens before it disappears. The skin shifts from purple to green to yellow, and yellow is a sign the trapped blood is being broken down and cleared.15PubMed Central. The practical application of reflectance spectrophotometry for the demonstration of haemoglobin and its degradation in bruises See a doctor if the goose egg isn’t getting smaller within the first day.16UPMC | Life Changing Medicine. How to Treat a Bump to the Head | UPMC HealthBeat
When a Bump Lingers or Changes Weeks Later
A healing goose egg shrinks steadily, day by day. A lump that stays the same size after two weeks deserves a check, and so does one that grows again after shrinking. Rarely, a soft fatty lump can form at an old injury site.
A hard blow to the temple can, rarely, damage the artery there and form a bulge in its wall.17PubMed Central. Enlarging traumatic superficial temporal artery pseudoaneurysm from a lacrosse ball injury: illustrative case It shows up as a painless lump that throbs with your heartbeat, usually 2 to 6 weeks after the injury.18PubMed Central. Enlarging traumatic superficial temporal artery pseudoaneurysm from a lacrosse ball injury: illustrative case It tends to keep growing over time.19PubMed Central. Superficial Temporal Artery Pseudoaneurysm Following Head Trauma from a Lacrosse Ball: A Case Report Any lump you can feel pulsing needs a doctor’s visit, not more icing.
Swelling on the forehead can also come from a pocket of infection in the bone.20PubMed. Pott’s puffy tumor: a forgotten differential diagnosis of frontal swelling of the forehead It usually follows an untreated sinus infection, but can also follow a blow to the head.21PubMed. Pott’s puffy tumor: A comprehensive review of the literature Forehead swelling with fever, redness, or recent sinus trouble needs prompt care.
Lumps That Appear Without an Injury
Cysts are the most common cause. A pilar cyst is a smooth, firm lump that grows from the root of a hair and shows up most often on the scalp.22PubMed Central. A Rare Hybrid Skin Cyst of the Scalp With Pilar and Apocrine Features Another kind of skin cyst is similar and can appear anywhere on the body, including the scalp.23PubMed Central. A Rare Hybrid Skin Cyst of the Scalp With Pilar and Apocrine Features A cyst that suddenly grows should be shown to a dermatologist.
Small lymph nodes sit at the base of the skull and drain the back of the scalp.24Klarity Health Library. Occipital Lymph Nodes: Causes, Symptoms & Care They swell when the body fights an infection nearby, like an irritated scalp or a cold.25Healthgrades. What Can Cause Swollen Occipital Lymph Nodes? In rubella, swelling often appears behind the ears and at the back of the neck.26withpower.com. Understanding Occipital Lymph Nodes
A small, rock-hard, painless lump that doesn’t move may be a little dome of extra bone on the skull’s outer surface.27PubMed Central. Button Osteoma: A Review of Ten Cases One that hasn’t changed for years is usually harmless.
Firm, itchy bumps at the base of the scalp that join into scar-like ridges can be acne keloidalis.28PubMed. Acne keloidalis: a review It is long-lasting and often painful, and is most common in young Black men.29Aglow Dermatology. Acne Keloidalis Nuchae
Touch gives clues. Cysts feel smooth and rubbery and can move slightly under the skin. Lymph nodes are often pea-sized and tender, and come and go with illness. Bone bumps are rock hard and fixed in place. Follicle bumps sit at the hairline and may itch.
A harmless cyst can be left alone if it doesn’t bother you. If it does, a doctor can remove it in a short office procedure. Squeezing one at home can cause infection and scarring, and a red, painful, swollen cyst may already be infected and needs care.
If you find a lump and haven’t had an injury, note when you first noticed it, how big it is, and whether it’s tender, since these are what a doctor asks first. Measure it against something fixed, such as a coin, and re-check every week or two to see whether it’s growing. Feel for the same lumps on the other side of the head and neck, because a pattern on both sides can point to lymph nodes responding to an infection.
Bumps on a Baby or Child’s Head
Doctors look at how the fall happened, such as how high it was and what the child landed on, since height and surface affect risk. They check alertness, whether the child acts like themselves, and whether they can move and balance normally. In babies they feel the soft spot on top of the head, since a bulging one can signal pressure. They also feel for swelling or dents in the skull and look for bruising in places that suggest a deeper injury. Doctors use a checklist made for children to decide who needs a CT scan, and it has caught every serious brain injury while sparing nearly 3 in 10 children a scan.30PubMed Central. PECARN Rule in diagnostic process of pediatric patients with minor head trauma in emergency department
At home, stay close for the first day and notice whether your child plays, eats, and talks the way they normally do. Letting them sleep is fine, but if they’re sleepy at an unusual time, wake them to check that they respond normally. Crying right after the fall is expected; crying that keeps going and can’t be settled is a reason to call, as are refusing to feed and repeated vomiting. Write down the time of the fall and any changes so you can describe them clearly.
A newborn may have a firm swelling on one side of the head from birth that stays within one skull bone and doesn’t cross the middle; this is usually harmless and fades on its own.31PubMed Central. Point-of-care Ultrasound to Distinguish Subgaleal and Cephalohematoma: Case Report A soft swelling that spreads across the whole head is a deeper bleed that needs urgent care.32PubMed Central. Point-of-care Ultrasound to Distinguish Subgaleal and Cephalohematoma: Case Report
A lump on a baby’s scalp since birth may be a dermoid cyst.33MDedge. Image Congenital Dermoid Cysts of the Scalp Doctors advise an MRI for these, especially if the lump is ringed by thicker, darker hair or a red birthmark.34MDedge. Image Congenital Dermoid Cysts of the Scalp
When a Scalp Lump Should Be Checked for Something Serious
Cancer that spreads to the scalp most often looks like red or purple lumps about 2 cm across.35PubMed Central. Diagnosis and Management of Scalp Metastases: A Review It can also appear as skin-coloured lumps.36PubMed Central. Diagnosis and Management of Scalp Metastases: A Review A new scalp lump in someone who has had cancer should be shown to their doctor soon.
For anyone, a lump deserves a visit if it keeps growing over weeks, bleeds, ulcerates, or changes colour. The same goes for one that feels hard and stuck to deeper tissue, or that comes with fever, weight loss, or night sweats.
The doctor feels the lump and asks how long it has been there. An ultrasound is often the first imaging test, and a small sample may be taken to confirm what it is.