Warning Signs After a Head Injury: What to Watch For in the First 24 Hours

Donald St Pierre, MSN, RN-BC
Nov 8, 2025
4 min read

A bump, blow, or jolt to the head can cause a brain injury. Sometimes symptoms show up right away. Other times they appear over the next 24 hours or more (Centers for Disease Control and Prevention [CDC], 2025; Verywell Health, 2025).

Most head injuries are mild, but a few can be life-threatening if they are missed. That’s why doctors and nurses teach families to watch for certain “red flag” warning signs and to go to the emergency department or call 911 if they appear (CDC, 2025; NICE, 2023).

Changes in Level of Consciousness (LOC)

LOC means how awake and alert someone is.

Get emergency help right away if, after a head injury, the person:

Becomes very sleepy or hard to wake up
Seems confused or doesn’t know where they are
Acts “not themselves”—restless, agitated, or can’t think clearly
“Keeps wanting to sleep” and is difficult to arouse

These can be signs of a serious brain injury or brain bleeding (CDC, 2025; Drugs.com, 2025).

Seizures

A seizure is when the body:

Shakes or jerks
Or the person stares and doesn’t respond for a period of time

Any seizure after a head injury is a 911 emergency (CDC, 2025; Concussion Alliance, 2024).

Bleeding or Clear Fluid From the Nose or Ears

Watch for:

Blood coming from the nose or ears (not just a little nosebleed from the front of the nose)
Clear, watery fluid dripping from the nose or ears

This could be cerebrospinal fluid (CSF) leaking, which is a sign of a possible skull fracture. This needs immediate emergency care (NICE, 2023; UF Health Jacksonville, 2025).

Slurred Speech

If the injured person:

Has trouble getting words out
Sounds like they are drunk or “tongue-tied”
Can’t speak clearly enough to be understood

This can be a sign of brain injury or stroke-like symptoms after trauma. Call 911 or go to the ER (CDC, 2025; CentraCare, 2021).

Pupils Slow to React or Unequal

The pupils are the black circles in the center of each eye.

Concerning signs include:

One pupil is bigger than the other
Pupils that don’t get smaller in bright light or don’t respond normally

Unequal or non-reactive pupils can be a sign of pressure on the brain and need emergency evaluation (CDC, 2025; Nebraska Medicine, 2022).

Visual Problems

After a head injury, get help if someone has:

Double vision (seeing two of everything)
Very blurry vision
Says “I can’t see right” or “something is wrong with my eyes”

These can mean the brain or the nerves to the eyes are affected and should be checked urgently (CDC, 2025; CentraCare, 2021).

Loss of Sensation or Weakness in Arms or Legs

Call 911 if the person notices:

Numbness or tingling in an arm, leg, hand, or foot
Any new weakness—for example, they can’t hold something or walk normally

This can be a sign of brain or spinal cord injury (CDC, 2025; NICE, 2023).

Projectile or Repeated Vomiting

Vomiting once from pain or shock can happen. But:

Repeated vomiting, or
Projectile vomiting (sudden, forceful vomit)

After a head injury is a danger sign and needs rapid medical care (CDC, 2025; Complete Concussions, 2023).

Other Serious Warning Signs

Major guidelines list several additional red flags that should send you to the ER or make you call 911 (CDC, 2025; NICE, 2023; Concussion Alliance, 2024):

A headache that gets worse and does not go away
Repeated or worsening confusion or behavior changes
The person cannot recognize people or places
Loss of consciousness, even for a short time, especially if they are hard to wake
Clumsiness or trouble walking
Any concern for neck or back injury—don’t move them unless they are in danger

What to Do If You See These Warning Signs

If someone has a head injury and you notice any of the danger signs above:

Call 911 or your local emergency number right away.
Do not let them drive themselves.
Keep them still and safe while you wait for help.
If they are vomiting or very sleepy and you’ve been taught how, gently roll them on their side to keep the airway clear—unless you suspect a neck or spine injury, in which case avoid moving them.
Tell the emergency team exactly what symptoms you saw and when the injury happened.

When in doubt, it is always safer to be checked.

Tee Shirt: Education You Can Wear (Head Injury Warning Signs Tee)

Your “Warning Signs After a Head Injury (First 24 Hours)” tee turns emergency discharge instructions into something people can see every day.

The design shows:

A cartoon character holding their head
Clear phrases like:
- Changes in LOC (drowsiness, confusion)
- Seizures
- Bleeding or fluid from nose or ears
- Slurred speech
- Pupils slow or unequal
- Visual problems
- Loss of sensation
- Projectile vomiting

These match danger signs listed by major organizations, including the CDC “Heads Up” concussion program and national head-injury guidelines (CDC, 2025; NICE, 2023; Drugs.com, 2025; UF Health Jacksonville, 2025).

When someone wears this shirt:

In the ER or urgent care, families sitting in the waiting room can quietly read and learn what to watch for when they go home.
At schools, sports events, or community programs, kids and parents see the list and start to understand that head injuries are serious and need monitoring.
It can spark conversations like:
“What does ‘changes in LOC’ mean on your shirt?”And then you (or your staff) get to explain in plain language—exactly what this blog teaches.

The more of these head-injury warning-sign tees are out in the world, the more people know:

Which symptoms are not normal after hitting your head
That these signs mean “go to the ER now”, not “wait and see”

That’s education you can wear—and it might literally save a life.

Head Injury Awareness

From$15.00

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References

Centers for Disease Control and Prevention. (2025). Symptoms of mild TBI and concussion and Concussion danger signs.

CentraCare. (2021). Warning signs of concussion.

Complete Concussions. (2023). When should I go to the emergency department for concussion?

Concussion Alliance. (2024). Immediate care: red flag symptoms.

Drugs.com. (2025). Head injury: discharge care.

Nebraska Medicine. (2022). Concussion symptom red flags and when to seek medical care.

National Institute for Health and Care Excellence (NICE). (2023). Head injury: assessment and early management (NG232).

UF Health Jacksonville. (2025). Signs of a head injury: What to look out for after an accident.

Verywell Health. (2025). Signs and symptoms to look for after head trauma.