Head Injury and Concussion: Danger Signs, First Aid and When to Go to the Emergency Room

Quick answer: after a blow to the head, watch for danger signs listed by the CDC, including one pupil larger than the other, drowsiness or inability to wake up, a headache that gets worse and does not go away, slurred speech, weakness, numbness or decreased coordination, repeated vomiting, convulsions or seizures, unusual behavior, confusion or agitation, and loss of consciousness. Any of these means emergency care right away. Milder symptoms such as headache, dizziness or feeling foggy suggest a concussion and should be checked by a health care provider. Do not move someone who may have a neck injury.

Head injuries are among the most common results of falls at home, on stairs and on slick winter sidewalks. Many are minor. Some are concussions, which are brain injuries even when the person never loses consciousness. A small number involve bleeding inside the skull that can become life-threatening hours after the injury, when the person may seem fine at first.

Knowing which signs call for emergency care helps you respond quickly and avoid two common mistakes: ignoring a serious injury, and panicking over a minor bump. This guide draws on the CDC’s HEADS UP program, the Mayo Clinic and the American Red Cross. It is part of our apartment emergency kit guide.

Sources: CDC HEADS UP, “Concussion Signs and Symptoms” and “Danger Signs”; CDC, “Traumatic Brain Injury and Concussion”; CDC STEADI older adult fall prevention resources; Mayo Clinic, “Head trauma: First aid” and “Concussion”; American Red Cross first aid guidance. Checked November 2026. This is general safety information, not medical advice. When in doubt about a head injury, seek medical care or call 911.

What a Concussion Is

The CDC describes a concussion as a type of traumatic brain injury caused by a bump, blow or jolt to the head, or by a hit to the body that makes the head and brain move rapidly back and forth. That sudden movement can cause the brain to bounce or twist in the skull, creating chemical changes and sometimes stretching and damaging brain cells.

Most people do not lose consciousness with a concussion. A person can walk, talk and seem mostly normal while still having one. Symptoms may appear right away or develop over hours or days.

Other head injuries include scalp cuts, skull fractures and bleeding in or around the brain. Bleeding inside the skull is the most dangerous, because pressure can build gradually.

Danger Signs That Need Emergency Care

The CDC’s HEADS UP program lists danger signs in adults that call for emergency care right away. Call 911 or go to the emergency department if the person has:

• One pupil (the black part in the middle of the eye) larger than the other
• Drowsiness or inability to wake up
• A headache that gets worse and does not go away
• Slurred speech, weakness, numbness or decreased coordination
• Repeated vomiting or nausea, convulsions or seizures (shaking or twitching)
• Unusual behavior, increased confusion, restlessness or agitation
• Loss of consciousness, even briefly

For children, the CDC adds signs such as inconsolable crying and refusing to nurse or eat in young children.

The Mayo Clinic also lists severe bleeding from the head or face, fluid or blood from the nose or ears, and changes in breathing as reasons to call 911.

Older adults and people on blood thinners

People 65 and older are at higher risk of serious bleeding inside the skull after even a minor fall, and the CDC reports that falls are the most common cause of traumatic brain injury among older adults. People taking blood-thinning medications have a further increased risk. Many emergency physicians advise that older adults and anyone on blood thinners be evaluated promptly after any head injury, even if they feel fine. If you or a family member takes a blood thinner, ask a doctor in advance what to do after a fall.

Common Concussion Symptoms

Symptoms that are not danger signs but still suggest a concussion fall into four groups, according to the CDC:

Type	Examples
Physical	Headache, nausea or vomiting, dizziness, balance problems, sensitivity to light or noise, blurry vision, feeling tired
Thinking and remembering	Feeling foggy or slowed down, trouble concentrating, trouble remembering new information
Emotional	Irritability, sadness, nervousness or anxiety, being more emotional
Sleep	Sleeping more or less than usual, trouble falling asleep

Anyone with these symptoms after a head injury should be checked by a health care provider, who can assess the injury and give guidance on recovery.

First Aid for a Head Injury

The Mayo Clinic and Red Cross give similar steps.

1. Check responsiveness and breathing. If the person is not breathing normally, call 911 and begin CPR. Our guide to hands-only CPR and AED basics covers the steps.
2. Keep the person still. If there is any chance of a neck or spine injury, such as after a fall from height, a car crash or a dive, do not move them unless they are in immediate danger. Support the head and neck in the position found.
3. Control bleeding. Press firmly on a scalp wound with a clean cloth or sterile gauze. If you suspect a skull fracture, apply gentle pressure around the edges of the wound rather than directly on it.
4. Do not remove objects. If something is stuck in the wound, leave it in place and pad around it.
5. Watch for danger signs. Stay with the person and monitor breathing, alertness and behavior.
6. Apply a cold pack to swelling, wrapped in a cloth, for comfort.
7. Call 911 or get medical care if any danger sign appears.

Scalp wounds bleed a lot

The scalp has many blood vessels close to the surface, so even small cuts can bleed heavily. That bleeding usually stops with firm, steady pressure for several minutes. A deep, gaping or long scalp cut may need stitches or staples. Heavy bleeding that does not slow with pressure calls for 911. Our guide to Stop the Bleed basics explains pressure technique.

Vomiting

If the person vomits and there is no suspected neck injury, roll them onto their side so they do not choke. If a neck injury is possible, the Red Cross teaches log-rolling with help, keeping the head, neck and back in line.

The Hours After a Head Injury

Many people wonder whether someone with a head injury should be kept awake. Current advice, reflected by sources such as the Mayo Clinic, is that if a health care provider has evaluated the person and found no serious injury, it is generally fine for them to sleep. Before an evaluation, watch for drowsiness or difficulty waking, which is a danger sign.

For the first day or so, have someone stay with the person and check on them. Watch especially for worsening headache, confusion, repeated vomiting, unusual sleepiness or changes in behavior, and go to the emergency department if they appear.

Avoid alcohol and drugs that were not prescribed, which can mask symptoms or slow recovery.

Recovery From a Concussion

The CDC’s guidance on concussion recovery has evolved. Rather than long periods of complete rest in a dark room, the CDC now advises a short period of relative rest, about the first couple of days, followed by a gradual return to normal activities as symptoms allow. Light activity, like short walks, is often encouraged early.

General recovery tips from the CDC include:

• Get enough sleep and keep a regular sleep schedule
• Limit activities that make symptoms worse, then gradually increase as tolerated
• Take breaks from screens if they worsen headaches or concentration
• Return to work or school gradually, with adjustments if needed
• Avoid activities with a risk of another head injury until a provider clears you

Most people recover within a few weeks, but some have symptoms that last longer. Ongoing symptoms should be discussed with a health care provider.

Never return to sports too soon

A second concussion before the brain has healed can cause more serious problems. The CDC advises that athletes with a suspected concussion be removed from play the same day and not return until cleared by a health care provider. Most states have laws requiring this for youth sports.

Head Injuries in Children

Young children fall often, from beds, changing tables, playground equipment and stairs. The CDC’s HEADS UP program notes that children may not be able to describe how they feel, so caregivers need to watch behavior closely. Signs to look for include crying more than usual, headache that does not go away, changes in the way the child plays or acts, changes in nursing, eating or sleeping patterns, loss of interest in favorite toys, and loss of new skills such as toilet training.

Call 911 or go to the emergency department for any of the danger signs listed earlier, or if a young child will not stop crying and cannot be consoled, or will not nurse or eat. For infants, a bulging soft spot on the head is another reason for urgent care. When in doubt, call your pediatrician’s office, which usually has a nurse line available after hours.

To prevent falls in young children, use safety gates at the top and bottom of stairs, install window guards or stops on upper floors, never leave a baby alone on a raised surface, and choose playgrounds with soft surfaces such as wood chips, rubber mulch or rubber mats.

What to Expect at the Hospital

At the emergency department, a clinician will ask how the injury happened, check symptoms and perform a neurological exam covering alertness, memory, balance, coordination and reflexes. Depending on risk factors, they may order a CT scan to look for bleeding or a fracture. Many people with mild head injuries do not need imaging and are sent home with instructions on symptoms to watch. Bring a list of medications, especially blood thinners, and note the time of the injury if you can.

Preventing Head Injuries at Home

Falls cause many head injuries, so fall prevention is head injury prevention. The CDC’s STEADI program recommends:

• Clear clutter from floors and stairs
• Add grab bars in the bathroom and railings on both sides of stairs
• Improve lighting, including night lights for bedrooms and halls
• Use non-slip mats in the shower and tub
• Have vision checked yearly and review medications that cause dizziness
• Do strength and balance exercises, such as tai chi, if appropriate

During outages and winter weather

Dark hallways and stairwells during a blackout are a common setting for falls. Keep flashlights or headlamps by the bed and the door. Our guide to emergency lighting for power outages covers good choices. On icy sidewalks, walk slowly with short steps and use handrails.

Helmets

Helmets reduce head injury risk for biking, scootering, skating and skiing. City cyclists and e-scooter riders are especially exposed to falls and traffic. Choose a helmet certified to the safety standard for the activity; the CPSC sets the federal standard for bicycle helmets.

What to Keep in Your Kit

A first aid kit supports head injury care with a few basic items:

• Sterile gauze pads and roller gauze for scalp bleeding
• Instant cold packs
• Disposable gloves
• A flashlight or penlight to check surroundings
• A printed card with the CDC danger signs

Our first aid kit for a small apartment guide lists the full set of supplies.

Frequently Asked Questions

Can you have a concussion without passing out?

Yes. The CDC notes that most concussions occur without loss of consciousness.

Should I go to the ER after hitting my head?

Go right away for any danger sign, such as worsening headache, repeated vomiting, confusion, drowsiness, unequal pupils, slurred speech, weakness or a seizure. Older adults and people on blood thinners should be evaluated after any significant head injury. For milder symptoms, see a health care provider.

Is it safe to sleep after a head injury?

After a health care provider has evaluated the person and ruled out a serious injury, sleep is generally fine. Before evaluation, drowsiness or trouble waking is a danger sign.

How long does a concussion last?

Most people feel better within a few weeks, according to the CDC, but recovery varies.

Can I take pain relievers after a head injury?

Ask a health care provider. Some pain relievers may not be recommended right after a head injury, especially if bleeding is a concern.

The Bottom Line

After any blow to the head, watch for danger signs: unequal pupils, drowsiness, a worsening headache, slurred speech, weakness, repeated vomiting, seizures, confusion or loss of consciousness, and call 911 if any appear. Do not move a person who may have a neck injury, control scalp bleeding with firm pressure and stay with the person. Older adults and people on blood thinners need prompt evaluation even after minor falls, and most concussions improve with brief rest followed by a gradual return to activity.