Concussion After a Car Accident: Signs, Memory Loss, Nausea, and When to Get Help
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This page was written and reviewed by Michael J. Cefali, Esq. Attorney Cefali is a founding partner of Cefali & Cefali, APC, based in San Juan Capistrano, CA. He holds a Juris Doctor from Chapman University Fowler School of Law and a B.A. in Global Studies & Maritime Affairs from the California Maritime Academy. Widely recognized for his advocacy in personal injury law, he has secured multi-hundred-thousand-dollar settlements in motorcycle accidents, hit-and-runs, and red-light collision cases. He maintains a perfect 10.0 “Superb” rating on Avvo.
Beyond his legal practice, Mr. Cefali actively supports his community through the Rotary Club of San Juan Capistrano, contributes to housing and meal programs for those in need, and enjoys fishing and spending time with his rescue dogs.
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Concussion After a Car Accident: Signs, Memory Loss, Nausea, and When to Get Help
You can have a concussion after a car accident even if you never hit your head and never blacked out. The most common signs are a headache that will not go away, nausea, dizziness, feeling foggy or slowed down, and trouble remembering the crash or what happened right after it. Some symptoms show up hours or days later, so getting checked within a day or two matters for both your health and any injury claim.
This guide covers how to tell if you have a concussion, why memory loss and nausea happen, which symptoms mean you need emergency care, and how a concussion is proven and valued in a California injury claim. Nothing here replaces a doctor's exam or advice from a lawyer about your own case; if you have symptoms, get medical care first.
How do you know if you have a concussion after a car accident?
Doctors classify a concussion as a mild traumatic brain injury, and no single test confirms it. Doctors diagnose it from your symptoms, how the injury happened, and an exam. The CDC groups concussion symptoms into four areas:
Physical: headache, nausea or vomiting, dizziness or balance problems, sensitivity to light or noise, blurry vision, and fatigue.
Thinking and memory: feeling foggy or slowed down, trouble concentrating, and problems with short-term or long-term memory.
Emotional: irritability, anxiety, sadness, or feeling more emotional than usual.
Sleep: sleeping much more or less than usual, or trouble falling asleep.
Other people often notice signs before you do. A passenger or witness may see that you looked dazed, answered questions slowly, slurred your words, or asked the same question more than once. Ask them to write down what they saw, because their account can matter later.
Can you get a concussion without hitting your head?
Yes. A concussion is caused by a bump, blow, or jolt that makes the head move quickly back and forth, which bounces or twists the brain inside the skull. In a rear-end or side-impact crash, the sudden stop and whipping motion of the neck can cause a concussion even when your head never touches the steering wheel, window, or airbag. This is the same motion that causes whiplash, which is why the two injuries often happen together.
Insurance adjusters sometimes argue there was no concussion because there was no head strike or no loss of consciousness. Neither is required. Most concussions happen without blacking out.
When do concussion symptoms show up after a crash?
Some symptoms start right away, while others appear hours or days later. According to the CDC, headaches and nausea tend to come early, while emotional changes and sleep problems may not appear until a week or two after the injury. Mayo Clinic also lists trouble concentrating, memory problems, irritability, and sensitivity to light and noise among the symptoms that can be delayed.
Adrenaline after a crash can mask how you feel at the scene, which is one reason people decline an ambulance and then feel worse the next morning. Delayed symptoms are common and do not mean the injury is unrelated to the crash. For a day-by-day look at recovery, read what the first week after a crash looks like.
Can a concussion cause memory loss?
Yes. Memory problems are one of the most common concussion symptoms. They usually take one of two forms:
Amnesia around the crash. Many people cannot remember the moments just before or after the collision. Mayo Clinic notes that amnesia surrounding the event is a typical concussion sign.
Short-term memory trouble afterward. Forgetting conversations, losing track of tasks, walking into a room and forgetting why, or repeating the same question.
For most people, memory problems improve as the brain heals. If they last beyond a few weeks, or get worse instead of better, tell your doctor. Symptoms that continue for more than three months are called persistent post-concussive symptoms, and they may need evaluation by a neurologist or a neuropsychologist. When memory or thinking problems last, the injury may be more than a mild concussion. Our traumatic brain injury guide explains how more serious brain injuries are handled in a claim.
Is nausea after hitting your head a sign of a concussion?
It can be. Nausea and vomiting are common early concussion symptoms, especially in the first hours after the injury. Feeling queasy once or twice, along with a headache, is typical of a mild concussion.
Repeated vomiting is different. Both the CDC and Mayo Clinic list it as a danger sign that needs emergency care, because it can signal bleeding or swelling in the brain. If you throw up more than once after a crash, do not wait to see if it passes.
When is a head injury after a crash an emergency?
Call 911 or go to an emergency room right away if you or someone else has any of these signs after a crash, based on CDC guidance:
A headache that gets worse and does not go away
Repeated vomiting
Weakness, numbness, or poor coordination
Seizures or convulsions
Slurred speech or unusual behavior
One pupil larger than the other
Confusion, restlessness, agitation, or not recognizing people or places
Loss of consciousness, extreme drowsiness, or being unable to wake up
Mayo Clinic adds clear fluid or blood from the nose or ears, ringing in the ears that will not stop, and dizziness that keeps coming back. Older adults and anyone taking blood thinners should be checked promptly after any head injury, even a minor one.
What should you do in the first days after a concussion?
Get a medical exam within 48 hours, even if you skipped the ER. Mayo Clinic recommends a medical evaluation within one to two days of any head injury. Tell the doctor you were in a car accident and describe every symptom, including ones that seem minor.
Follow your doctor's return-to-activity plan. Most people are told to rest briefly and then return to normal activity gradually. Ask when it is safe to drive, work, exercise, and use screens.
Keep a symptom journal. Write down headaches, dizziness, memory lapses, sleep changes, and mood changes each day, with dates. This helps your doctor and documents the injury.
Keep every follow-up appointment. Gaps in treatment are one of the most common reasons insurers reduce concussion claims.
Be careful what you tell the insurer. Saying "I'm fine" in a recorded statement the day after a crash can be used against you if symptoms appear later.
Most people feel better within a couple of weeks, and most recover fully. Some symptoms, such as headaches and dizziness, can last days to weeks. A smaller group has symptoms that last months. Recovery tends to take longer for people who have had concussions before, and a second head injury before the first has healed can make symptoms worse, which is why doctors limit contact sports and risky activities during recovery.
How do you prove a concussion in a car accident claim?
Concussions are hard to see. A CT scan is used to rule out bleeding, and a normal scan does not mean there was no concussion. Because of this, insurers often dispute concussion claims with three arguments: there was no loss of consciousness, the scans were normal, or there was a gap in treatment. The evidence that answers those arguments includes:
Early medical records from the ER, urgent care, or your doctor that note head-injury symptoms and connect them to the crash.
Paramedic and police reports that describe you as dazed, confused, or slow to respond.
Witness statements from passengers or bystanders about what they saw right after the crash.
Your symptom journal and statements from family or coworkers about changes in memory, mood, or concentration.
Specialist evaluations, such as neurology, neuropsychological testing, or vestibular therapy for balance problems, when symptoms last.
Vehicle damage and crash details that show the force of the impact.
What compensation can you recover for a concussion in California?
If another driver caused the crash, the claim can cover ER and specialist bills, therapy you will still need, paychecks you missed, and any lasting effect on your ability to work. It also covers the harder-to-measure losses: headaches, anxiety, sleepless nights, and the activities you had to give up. There is no state cap on those non-economic damages in a car crash case. Our guide to economic vs non-economic damages explains how each category is calculated.
A concussion that heals in two weeks is valued very differently from one that causes months of headaches, missed work, and memory problems. The value depends on how long symptoms last, the treatment you needed, and how the injury affected your work and daily life. Sharing some of the blame lowers the award by your percentage instead of wiping it out, under California's pure comparative fault rule.
What is the deadline for a concussion injury claim in California?
California's general deadline for an injury lawsuit is two years, counted from the day of the collision (Code of Civil Procedure section 335.1). The window is much shorter when a city bus, county truck, or poorly maintained public street played a part: the agency has to get a written claim from you first, typically inside six months (Government Code section 911.2). Concussion symptoms can drag on for weeks, so check your deadline early instead of waiting to see how recovery goes.
Frequently asked questions
Can you have a concussion without losing consciousness?
Yes. Most concussions happen without any loss of consciousness. Symptoms such as headache, nausea, dizziness, fogginess, and memory problems are enough for a doctor to diagnose a concussion.
Can you get a concussion from whiplash?
Yes. A concussion can be caused by a jolt that makes the head move rapidly back and forth, even if the head never hits anything. The same sudden motion in a rear-end crash that causes whiplash can cause a concussion.
How long after a car accident can concussion symptoms appear?
Some symptoms appear right away, but others can take hours or days. The CDC notes that emotional changes and sleep problems may not appear until a week or two after the injury.
Is memory loss after a car accident normal?
Not remembering the crash itself is common with a concussion, and short-term memory trouble afterward is a typical symptom. If memory problems last more than a few weeks or get worse, see your doctor.
When should I go to the ER for a concussion?
Go right away for repeated vomiting, a headache that keeps getting worse, seizures, slurred speech, weakness or numbness, unequal pupils, confusion, or trouble staying awake.
Will a CT scan show a concussion?
Usually not. A CT scan is used to look for bleeding or skull fractures. A normal CT scan does not rule out a concussion, which is diagnosed from symptoms and an exam.
Hurt in a car accident? Talk to a California injury attorney
If a crash left you with a concussion, headaches, or memory problems, Cefali & Cefali can help you document the injury and pursue full compensation while you focus on recovering. Reach our team at (949) 325-7790 or through our contact page. The consultation is free, and our fee comes only from what we recover.
Michael Cefali is a dedicated accident attorney based in San Juan Capistrano, California, committed to securing justice and fair compensation for accident victims.
A graduate of Newport Harbor High School, he went on to earn his Bachelor’s degree in Global Studies and Maritime Affairs from the California Maritime Academy, followed by his Juris Doctor from Chapman University School of Law.
Deeply invested in his community, Michael is an active member of the Rotary Club of San Juan Capistrano, contributing to efforts that provide meals, housing, and support to those in need. Outside of his legal work and volunteer service, he enjoys fishing in Dana Point and spending time with his three rescue dogs—a Chihuahua, a Spaniel mix, and a Shepherd mix.
Driven by his strong belief in justice and fairness, Michael remains steadfast in advocating for individuals harmed by the negligence or inaction of others.
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