Reviewed by Larry Forman, Attorney
Many people walk away from a crash feeling shaken but fine, then wake up the next day with a headache, fog or trouble sleeping. A concussion after a car accident is easy to miss, both for the person who has it and for the doctors who see them first. That delay can affect your health, and insurers use it against your claim.
This post covers what the CDC says about late concussion symptoms, the warning signs that need emergency care, and how to protect your claim if your symptoms showed up later.
What a concussion is
The CDC calls concussion a mild traumatic brain injury (TBI). It's caused by "a bump, blow, or jolt to the head, or by a hit to the body that causes the head and brain to move quickly back and forth" (CDC). You don't have to hit your head. The sudden stop in a crash can be enough.
"Mild" doesn't mean minor. The CDC explains that health care providers "may describe these injuries as mild because they are usually not life-threatening. Even so, the effects of a mild TBI or concussion can be serious."
Why symptoms can show up late
According to the CDC, "Some mild TBI and concussion symptoms may appear right away, while others may not appear for hours or days after the injury" (CDC). Symptoms can also change during recovery. The CDC notes that "a week or two after your injury you may notice you feel more emotional than usual or have trouble sleeping."
At the scene, adrenaline and more obvious injuries, like a cut or a painful neck, can hide the signs. The CDC also says "a person may not recognize or admit that they are having problems," and problems may be overlooked by the injured person, their family or their health care provider.
Signs of a concussion after a car accident
The CDC groups common symptoms into four areas:
- Physical: headaches, dizziness or balance problems, nausea or vomiting early on, sensitivity to light or noise, vision problems, feeling tired
- Thinking: trouble concentrating or paying attention, feeling slowed down or foggy, memory problems, trouble thinking clearly
- Emotional: anxiety, irritability, sadness, feeling more emotional than usual
- Sleep: sleeping less or more than usual, trouble falling asleep
Most people feel better within a couple of weeks, the CDC says. When symptoms last longer or get worse, follow up with your doctor.
When to go to the ER
The CDC lists danger signs in adults that call for emergency care right away:
- A headache that gets worse and doesn't go away
- Weakness, numbness, decreased coordination, convulsions or seizures
- Repeated vomiting
- Slurred speech or unusual behavior
- One pupil larger than the other
- Confusion, restlessness or agitation, or not recognizing people or places
- Losing consciousness, being very drowsy, or being unable to wake up
The CDC also warns that people taking blood thinners, including aspirin, may have a higher risk of bleeding in the brain after a TBI, and that older adults who've been in a car crash should be checked. For where serious injuries are treated locally, see our guide to Louisville trauma centers.
A normal CT scan doesn't rule out a concussion
Many people are told their scan was "normal" and assume that means no injury. The CDC says a brain scan such as a CT "is not needed to spot a mild TBI or concussion," though it may be used for patients at risk of bleeding. And "even if the injury doesn't show up on these tests, you may still have a mild TBI or concussion."
Insurers often point to a normal scan to argue nothing happened. Your symptoms, your doctors' notes and testing of thinking and memory can say otherwise.
How a late diagnosis affects your claim
A delayed concussion diagnosis is common, but insurers will ask:
- Why didn't you mention it at the scene or in the ER? The answer is often in the CDC's own guidance: symptoms can appear hours or days later.
- Is something else causing it? Gaps in treatment or a later fall give the insurer an opening.
- Are you exaggerating? Concussion symptoms are hard to see, so insurers lean on photos and social media. See insurance adjuster tactics.
What helps:
- See a doctor as soon as symptoms appear, and say you were in a crash.
- Describe every symptom, including fog, irritability and sleep changes, not just headaches.
- Keep a short daily journal: symptoms, missed work, things you couldn't do.
- Ask family or co-workers to note changes they see. They often notice first.
- Follow your treatment plan and keep appointments. Ask for a referral if symptoms don't improve.
- Get copies of your records. See how to request your medical records.
Concussions often happen alongside whiplash and neck injuries. Make sure both are documented.
Kentucky law in brief
- PIP pays first. Your own no-fault coverage generally pays early medical bills and lost wages, up to $10,000, unless you rejected it. See how Kentucky PIP insurance works.
- The tort threshold. To claim pain and suffering from the at-fault driver, you generally need more than $1,000 in medical expenses or a qualifying injury, such as a permanent injury (KRS 304.39-060). Concussion care, imaging and follow-up visits often pass the $1,000 mark.
- A prior concussion doesn't bar your claim. The at-fault driver is responsible for making an earlier condition worse. The CDC notes that repeated concussions can lead to longer recovery.
- The deadline. For most motor vehicle injury claims, two years from the injury or the last PIP payment, whichever is later (KRS 304.39-230). See our statute of limitations guide.
The full effect of a concussion may not be clear for months. Settling early can leave out care you'll need later. See what affects a Kentucky injury case's value.
How Forman & Associates helps
We gather the crash evidence that shows the forces involved, connect your symptoms to the crash through your records and treating doctors, track the ways a concussion affects your work and home life, and don't settle before the picture is clear. When an insurer won't be fair, we're ready for court: Larry Forman has tried 50+ jury trials and won 95% of them. For more serious injuries, see our traumatic brain injury page.
Concussion after a car accident FAQ
How long after a car accident can concussion symptoms start?
The CDC says some symptoms appear right away, while others may not appear for hours or days. Some, like emotional changes or trouble sleeping, may show up a week or two later.
Can you have a concussion without hitting your head?
Yes. The CDC says a hit to the body that makes the head and brain move quickly back and forth can cause a concussion. The sudden stop in a crash can be enough.
My CT scan was normal. Can I still have a concussion?
Yes. The CDC says a CT scan isn't needed to spot a concussion, and an injury may not show up on tests even when it's there.
Is it too late to claim a concussion if I didn't mention it at the ER?
Usually not. Delayed symptoms are common. See a doctor as soon as you notice them, explain that you were in a crash, and keep records.
Can I recover for a concussion in Kentucky if I had one before?
Yes. An at-fault driver is responsible for making an earlier condition worse. Records from before the crash help show the difference.
Talk to a Louisville car accident lawyer
If you have a concussion after a car accident, call Forman & Associates Accident Injury Lawyers at (502) 931-6788 or get a free case evaluation. Our office is at 1139 S. 4th St., Louisville, KY 40203. No fee unless we win.
This post is general information about Kentucky law, not legal advice. Reviewed October 2026.
