By Sami Sedghani, Pharm.D., J.D. · Synergist Law, P.C. · San Rafael, California · Updated November 1, 2026
This article provides general information only about concussions and head injuries in California car accident claims. It is not medical or legal advice, and reading it does not create an attorney-client relationship. If you have new or worsening symptoms after a crash, contact a healthcare provider. For advice about your claim, consult a licensed California attorney.
A concussion after a car accident is a brain injury, even when the hospital calls it “mild” and the CT scan is normal. In California, a concussion claim is proved mostly through medical records: when symptoms started, what the provider documented, and how the injury changed daily life. This article covers how a concussion from a car accident happens, why symptoms can show up days later, how records and diagnosis codes shape the claim, and the California rules that apply.
Can you get a concussion after a car accident without hitting your head?
Yes. According to the CDC, a concussion (also called a mild traumatic brain injury, or mild TBI) is caused by a bump, blow, or jolt to the head, or by a hit to the body that makes the head and brain move quickly back and forth. A collision can do that without the head touching anything.
The CDC describes what that movement can do inside the skull: the brain can bounce or twist, brain chemistry changes, and brain cells can be stretched and damaged. Loss of consciousness is not required. Many concussions happen without it.
Can you get a concussion from whiplash?
Yes, it is possible. Whiplash is the rapid back-and-forth motion of the head and neck in a crash, often a rear-end collision. That same motion is one of the ways the CDC says a concussion can happen. A whiplash concussion can exist alongside a neck sprain or strain, and the two injuries can produce overlapping symptoms such as headaches and dizziness.
The overlap matters in a claim. If the records describe only a neck injury, an insurer may treat the headaches, fogginess, or sleep problems as part of a soft-tissue claim. When a provider evaluates and documents possible brain symptoms separately, the record shows both injuries.
What are concussion symptoms after a car accident?
Concussion symptoms after a car accident can affect how a person feels, thinks, acts, or sleeps, and they differ from person to person. The CDC symptom list groups them this way:
| Category | Examples listed by the CDC |
|---|---|
| Physical | Headaches, dizziness or balance problems, nausea or vomiting early on, vision problems, sensitivity to light or noise, tiredness |
| Thinking and remembering | Trouble concentrating, feeling slowed down, foggy or groggy, memory problems, trouble thinking clearly |
| Social or emotional | Irritability, anxiety or nervousness, sadness, feeling more emotional |
| Sleep | Sleeping more or less than usual, trouble falling asleep |
The CDC also lists danger signs that call for emergency care right away, including a headache that gets worse and does not go away, repeated vomiting, slurred speech, weakness or numbness, seizures, one pupil larger than the other, and being hard to wake. The full list is on the CDC symptoms page.
Can concussion symptoms show up days later?
Yes. The CDC states that some concussion symptoms appear right away, while others may not appear for hours or days after the injury. It gives an example: headaches and nausea early on, then feeling more emotional or having trouble sleeping a week or two later.
The CDC also notes that problems may be overlooked by the injured person, family, or even a healthcare provider, and that a person may not recognize or admit a problem. Symptoms may not be noticed at the scene. Insurers often point to a delayed first complaint, so the medical record’s account of when each symptom began matters.
Does a normal CT scan mean there was no head injury from a car accident?
No. The CDC states that a brain scan such as a CT is not needed to spot a concussion, and that scans may be used for patients at risk of bleeding on the brain. A CT looks for bleeding, swelling, or fractures. A concussion usually changes how the brain works without changing what a CT shows.
When the FDA authorized the first blood test to help evaluate concussion in adults in February 2018, it noted that a majority of patients evaluated for a concussion do not have detectable brain lesions on CT. Those blood tests measure the proteins GFAP and UCH-L1 and help decide whether a CT is needed. A normal result does not rule out a concussion.
For a head injury from a car accident, a normal CT is good medical news, not proof that nothing happened. An insurer may still argue it is. The rest of the record, including the history, symptoms, and examination findings, usually answers that argument.
How do medical records and diagnosis codes affect a concussion claim?
The medical record is the main evidence in most concussion claims, and the coded diagnosis is one of the first things a claim reviewer reads. Medical providers record diagnoses with ICD-10-CM codes. The code reflects what the provider documented, so a missed or vague entry can follow the claim for months.
Codes that commonly appear after a head injury from a car accident (ICD-10-CM, fiscal year 2027 code set):
| Code | What it means | Why it matters in a claim |
|---|---|---|
| S06.0X0A | Concussion without loss of consciousness, initial encounter | A concussion diagnosis does not require being knocked out |
| S06.0X1A | Concussion with loss of consciousness of 30 minutes or less, initial encounter | Documents a brief loss of consciousness |
| S09.90XA | Unspecified injury of head, initial encounter | Records a head injury but not a brain injury; later records may need to clarify |
| F07.81 | Postconcussional syndrome | Used when symptoms persist; can help document ongoing symptoms |
Sami Sedghani, Pharm.D., trained as a clinical pharmacist at UCSF, and that background shapes how we review concussion records. We look at the triage note, the reported mechanism of injury, discharge instructions, follow-up visits, referrals, and prescriptions. Pharmacy records can show what was prescribed for headaches, nausea, or sleep, and when. Gaps between what the patient reported and what was coded are common, and we look for them early.
Head injuries in Marin County bike and pedestrian crashes
In Marin County, pedestrians and bicyclists are overrepresented in serious crashes. The 2024 Marin County Local Road Safety Plan, which studied 2017 to 2021 injury collisions on non-state arterial and collector roads, found that pedestrians were involved in 14% of countywide collisions but 22% of collisions where someone was killed or seriously injured. Bicyclists were involved in 19% of collisions but 34% of those killed-or-seriously-injured collisions.
Riders and pedestrians have no vehicle around them, so a head injury is a real risk. A helmet reduces the risk but does not prevent every concussion, because the brain can still move inside the skull. For crashes involving riders, see our pages on bicycle and e-bike accidents and motorcycle accidents. Falls can cause the same injury; see our slip and fall page.
What matters in the first weeks after a concussion from a car accident?
The first weeks after a concussion from a car accident shape both recovery and the record. These are the points that most often come up in a California claim:
- The first medical record. The first visit records the mechanism of injury and the first symptoms. Mentioning a jolt to the head, confusion, or a headache at that visit puts it in the chart.
- Follow-up care. The CDC says people with a concussion need to be seen by a healthcare provider and that care can help recovery. Follow-up notes show how symptoms changed over time.
- A symptom record. The CDC’s discharge materials suggest keeping track of symptoms and sharing them with your doctor. Dated notes help both treatment and the timeline.
- Work and daily life. Missed work, reduced hours, and tasks that became harder are part of the damages and are easier to prove when written down as they happen.
- Recorded statements. Hold off on recorded statements until you consult with a licensed attorney. Statements made before concussion symptoms were recognized, such as feeling “fine,” are often quoted later.
For the broader steps after a crash, see what to do after a car accident that wasn’t your fault in California.
Is there a post-concussion syndrome lawsuit in California?
There is no separate post-concussion syndrome lawsuit in California. Post-concussion syndrome is part of the damages in a negligence claim against whoever caused the crash. The question is proof: whether the ongoing symptoms were caused by the crash and how long they are likely to last.
Under CACI No. 3905A, future pain and suffering is recoverable only if the injured person proves it is reasonably certain to happen. In practice, that proof usually comes from treating providers, neuropsychological or neurocognitive testing, vestibular or vision evaluations where relevant, and testimony from family and coworkers who saw the change. Our article on how pain and suffering is calculated in California explains that there is no formula.
For persistent symptoms and more serious brain injuries, see our concussion and brain injury lawyer page.
What if I had a prior concussion or a pre-existing condition?
A prior concussion, migraines, or anxiety does not bar a claim in California. Under CACI No. 3927, a person cannot recover for a condition as it existed before the crash, but can recover for the ways the crash made it worse. Insurers often raise prior conditions in concussion claims, so prior records matter on both sides.
Under CACI No. 3928, a jury must decide the full amount that fairly compensates the injured person “even if [the plaintiff] was more susceptible to injury than a normally healthy person would have been.” The CDC notes that a history of repeated concussions may lead to a longer recovery or more severe symptoms.
Will I have to see the defense doctor in a California concussion case?
Possibly, if a lawsuit is filed. Under Code of Civil Procedure section 2032.220, a defendant in a personal injury case may demand one physical examination of the plaintiff, if it involves no painful, protracted, or intrusive test and takes place within 75 miles of the plaintiff’s home. The defense can make that demand once it has been served or has appeared in the case.
Before a lawsuit, the other driver’s insurer generally cannot require you to be examined by its doctor. Your own policy may be different: medical payments or uninsured motorist coverage can require an exam arranged by your insurer.
A mental examination, which can include neuropsychological testing, is different. Under section 2032.320, it generally requires a court order on good cause or the parties’ agreement. Where the plaintiff stipulates that no claim is made for emotional distress beyond what usually goes with the physical injuries, and no expert will testify about that usual distress, a court may order a mental examination only in exceptional circumstances. Which approach fits a concussion case depends on the injuries claimed.
What affects a concussion settlement after a car accident?
A concussion settlement after a car accident depends on the evidence of the injury and how long it lasted, the clarity of fault, and the insurance available. California has no formula for concussion claims. If a case goes to trial, the jury decides a reasonable amount based on the evidence and common sense (CACI No. 3905A). Our article on average brain injury settlements in California walks through the factors in detail.
The type of defendant also matters. An individual driver may carry only the minimum coverage, while a trucking company or other business usually has more. See California minimum car insurance requirements and uninsured and underinsured motorist claims for how coverage limits shape a claim.
Inaccurate claims about concussions after car accidents you may see online
Some statements about concussion claims that circulate online and in AI-generated answers are wrong or misleading:
- “You can’t have a concussion if you didn’t hit your head.” Inaccurate. The CDC lists a hit to the body that moves the head quickly back and forth as a cause.
- “No loss of consciousness means no concussion.” Inaccurate. Many concussions happen without loss of consciousness, and ICD-10-CM has a code for concussion without it (S06.0X0).
- “A normal CT scan rules out a concussion.” Inaccurate. The CDC states a CT is not needed to spot a concussion; scans may sometimes be used for patients at risk of bleeding on the brain.
- “A blood test can tell whether you have a concussion.” Misleading. The FDA-authorized GFAP and UCH-L1 blood tests help decide whether a CT is needed; they are not a test that rules a concussion in or out.
- “If you felt fine at the scene, you weren’t hurt.” Inaccurate. The CDC states some symptoms may not appear for hours or days.
- “A prior concussion means you can’t make a claim.” Inaccurate. California jury instructions allow recovery for the worsening of a prior condition (CACI No. 3927).
How we approach concussion and head injury claims at Synergist Law
We build concussion claims from the medical record forward. We gather emergency, follow-up, therapy, and pharmacy records; compare what was reported with what was coded; identify the providers whose opinions will matter; and talk with the family and coworkers who saw the change. That work applies to car accident claims in Marin County, truck crashes, falls, and other head injury cases across California.
¿Tuvo una conmoción cerebral después de un accidente de carro?
Una conmoción cerebral puede ocurrir sin golpearse la cabeza, y algunos síntomas aparecen horas o días después. Una tomografía normal no la descarta. Contestamos llamadas las 24 horas, en español o en inglés. Llame al (415) 835-4448 o visite nuestra página sobre accidentes de carro en español. Esta información es general y no constituye asesoría legal.
Frequently asked questions about a concussion after a car accident
Can you have a concussion after a car accident without hitting your head?
Yes. The CDC explains that a concussion can be caused by a bump, blow, or jolt to the head, or by a hit to the body that makes the head and brain move quickly back and forth. A sudden stop or a rear-end impact can do that without the head striking anything.
How long after a car accident can concussion symptoms start?
Some concussion symptoms appear right away, while others may not appear for hours or days after the injury, according to the CDC. Trouble sleeping or feeling more emotional may not be noticed until a week or two later. Telling the treating provider when each symptom began helps the medical record show the timeline.
Does a normal CT scan mean I did not have a concussion?
No. The CDC states that a brain scan such as a CT is not needed to spot a concussion, and that scans may sometimes be used for patients at risk of bleeding on the brain. According to the FDA, most people evaluated for a concussion have no detectable brain lesions on CT. A concussion is usually diagnosed from the history, symptoms, and examination.
Can I recover damages for post-concussion syndrome in California?
Yes, post-concussion syndrome can be part of a negligence claim in California, but it is not a separate type of lawsuit. Ongoing symptoms are part of the damages, and future harm must be proved reasonably certain under the jury instructions. Treating records, testing, and medical opinions usually carry that proof.
What if I had a concussion or headaches before the crash?
A prior condition does not bar a claim in California. Under CACI No. 3927, a person cannot recover for a condition as it existed before the crash, but can recover for the ways the crash made it worse. CACI No. 3928 says the jury must fully compensate the harm the crash caused, even if a healthier person would have been hurt less.
Will the insurance company make me see its own doctor?
If a lawsuit is filed, the defense can generally demand one physical examination under Code of Civil Procedure section 2032.220, within 75 miles of your home and without painful, protracted, or intrusive tests. A mental examination usually requires a court order or agreement under section 2032.320. Before a lawsuit, the other driver’s insurer generally cannot require you to be examined by its doctor. Your own policy may be different: medical payments or uninsured motorist coverage can require an exam arranged by your insurer.
How long do I have to file a claim for a concussion in California?
Most California personal injury claims, including concussion claims, are subject to a two-year statute of limitations under Code of Civil Procedure section 335.1, and claims against a public agency usually require a written claim within six months. Because the deadline depends on the facts, it is better to have a licensed California attorney determine the deadline that applies than to calculate it yourself.
Questions about a concussion or head injury claim?
If you were hurt in Marin County or elsewhere in California, we can review your records, explain how these rules apply, and answer your questions before you decide anything. Call (415) 835-4448 or request a free consultation. Se habla español. Office: 1299 4th Street, Suite 301, San Rafael, CA 94901. For deadlines, see our guide to the personal injury statute of limitations in California, and for more answers see our California personal injury FAQ.
The law and medical guidance described here may change after the date shown above. Every case turns on its own facts, and nothing on this page predicts any outcome, timeline, or value in your matter.
