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Published October 30, 2026

Concussion after a car crash: signs you should not ignore

Concussion symptoms can show up hours or days after an accident. What they are, which ones are an emergency and why it is worth getting checked.

In a crash, your head does not have to hit anything to get hurt. A hard jolt is enough to move the brain inside the skull. That is a concussion, and it is easy to miss because it almost never shows on the outside.

What a concussion is

The Centers for Disease Control and Prevention (CDC) describe it as a type of mild traumatic brain injury, caused by a bump, blow or jolt to the head or body. “Mild” means it is usually not life-threatening, not that it does not matter: its effects can be serious and last for weeks.

Symptoms can take time

According to the CDC, some symptoms appear right away, but others may not appear for hours or days. Headache and nausea tend to come first; mood changes and sleep problems can show up a week or two later.

The most common:

  • Physical: headache, dizziness or balance problems, nausea, fatigue, blurry vision, sensitivity to light or noise.
  • Thinking: trouble concentrating, feeling slowed down or foggy, memory problems.
  • Mood: irritability, anxiety, sadness, feeling more emotional than usual.
  • Sleep: sleeping more or less than usual, or trouble falling asleep.

Emergency signs

The CDC say to call 911 or go to the emergency department right away if, after the accident, you or someone else has:

  • A headache that gets worse and does not go away.
  • Weakness, numbness, poor coordination, convulsions or seizures.
  • Repeated vomiting.
  • Slurred speech or unusual behavior.
  • One pupil larger than the other.
  • Confusion, not recognizing people or places, restlessness or agitation.
  • Loss of consciousness, extreme drowsiness or being unable to wake up.

These signs are not something to save for a clinic appointment.

If you just feel “off”

Most concussions come without emergency signs, but with things that do not add up: work is hard to focus on, the screen bothers your eyes, you have slept badly since the crash. Those are worth a visit. A doctor can assess you, tell you how much rest you need and when to go back to driving, work or exercise, and get it all documented.

How we handle it at the clinic

We assess you after the accident, document your symptoms, especially the ones that show up late, and follow up while you recover. Accident care is normally covered by PIP in Utah, and the visit happens in English or Spanish.

Sources


This article is general information about our clinic and about concussion. It is not medical or legal advice and does not replace a consultation with a professional. If you have a medical emergency, call 911.

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