Concussion After a Car Accident: Symptoms and Red Flags

If your head hit something during a car accident, or if it snapped forward and back as the cars collided, you may have suffered a concussion even if you never lost consciousness. Many concussions after car crashes are missed at the scene because the worst symptoms do not show up until hours or days later.

A concussion is a brain injury. It is usually mild, but it is still an injury that benefits from a real evaluation rather than a "wait and see" approach. Some symptoms look like ordinary post-accident soreness or stress at first, then quietly get worse over the next 24 to 72 hours.

This guide explains what a concussion is, why car accidents cause them so often, the symptoms to take seriously, when the ER is the right call instead of urgent care, and how Florida's PIP rules give you a tight 14-day window to be evaluated. If you were in a crash anywhere in Palm Beach County, you can be seen the same day at our walk-in car accident injury clinic.

What a Concussion Actually Is

A concussion is a form of mild traumatic brain injury (mTBI). It happens when the brain moves suddenly inside the skull, briefly disrupting how brain cells communicate. The word "mild" describes how doctors classify the injury in a clinical sense, not how serious it feels. Many concussions take weeks to resolve, and some lead to longer symptoms called post-concussion syndrome.

You do not have to hit your head, and you do not have to black out, to suffer a concussion. A hard jolt to the body that makes the head whip can do it. That is why concussions and whiplash often occur together. We cover the neck side of that injury pattern on our whiplash treatment page.

Why Concussions Happen So Often After a Car Accident

In a crash, your body is restrained by the seatbelt, but your head and brain still move. The brain sits in cerebrospinal fluid inside the skull. A sudden change in motion makes the brain shift and, in some cases, strike the inside of the skull. That mechanism can stretch nerve fibers and trigger a chemical cascade that produces concussion symptoms.

Common car-accident mechanisms that cause concussions:

• Rear-end collisions: the body lurches forward against the belt while the head whips back, then forward.

• Side-impact (T-bone) crashes: the head accelerates laterally and may strike the window or door pillar.

• Airbag deployment: a deployed airbag protects the chest but can deliver a direct blow to the face and forehead.

• Head striking the steering wheel, headrest, or window: the most obvious cause, and not always remembered after the fact.

• Whiplash without direct head impact: pure rapid acceleration and deceleration of the head can be enough.

Speed matters less than people assume. Low-speed rear-end collisions, sometimes around 15 to 25 miles per hour, can still produce concussions.

Common Concussion Symptoms After a Crash

Concussion symptoms fall into four general groups. You do not need to have all of them, and you do not need them to appear right away.

Thinking and memory

• Feeling slowed down or in a fog

• Trouble concentrating or following a conversation

• Trouble remembering new information

• Feeling more confused than usual, especially in the first hours after the crash

Physical

• Headache or a feeling of pressure in the head

• Nausea or vomiting

• Dizziness or balance problems

• Sensitivity to light or noise

• Blurred or double vision

• Fatigue or low energy

Emotional and mood

• Feeling irritable, anxious, or unusually sad

• Mood swings that are out of character

Sleep

• Sleeping more or less than usual

• Trouble falling asleep

If you notice any combination of these symptoms in the hours or days after a crash, get evaluated. It is not normal to "shake off" symptoms that affect thinking, balance, or vision after a head jolt.

Red-Flag Symptoms That Require Emergency Care

Most concussions can be assessed at a walk-in clinic by a medical doctor. But some symptoms point to a more serious brain injury that needs an emergency room right away.

Call 911 or go to the ER if you experience any of these after a crash:

• Headache that gets steadily worse and will not ease

• Repeated vomiting

• Seizures or convulsions

• Loss of consciousness, even briefly

• Slurred speech

• Weakness, numbness, or decreased coordination on one side of the body

• One pupil larger than the other

• Clear fluid draining from the nose or ears

• Increasing confusion, restlessness, or agitation

• Inability to wake up or stay awake

These symptoms can indicate bleeding inside the skull, a skull fracture, or a more severe brain injury, and they need imaging and observation that an ER provides.

Why Concussion Symptoms May Not Show Up Right Away

In the minutes after a crash, your body releases a surge of adrenaline. Adrenaline blunts pain and sharpens focus, which is why many people walk away from a crash convinced they are fine. As the adrenaline wears off, real symptoms have room to surface.

Concussion symptoms commonly appear within the first 24 to 72 hours, sometimes longer. A headache the next morning, dizziness on standing up, or feeling unusually foggy at work two days later are all worth taking seriously. We explain this delayed-onset pattern across other accident injuries in our guide on back and neck pain after a car accident.

Urgent Care or ER for a Suspected Concussion?

If you have any of the red-flag symptoms above, go to the ER. Otherwise, urgent care with a medical doctor is often the right setting for a concussion evaluation: shorter wait, similar workup, and full documentation for your PIP records.

A walk-in urgent care that handles accident injuries can be appropriate when you have:

• Headache, dizziness, light sensitivity, or fogginess that is steady or improving

• No loss of consciousness, or a brief loss in the moment of impact with normal alertness since

• No vomiting, seizures, weakness, or vision change

• A need to start the PIP documentation paperwork the same day

The ER is the right call when:

• Any of the red-flag symptoms above are present

• You are on blood thinners

• You are pregnant

• You are over 65 and had a head injury

Not sure where to go? Our short comparison guide on urgent care versus the ER after a car accident walks through the decision in more detail.

Florida's 14-Day PIP Rule and Concussions

Florida is a no-fault state for car-accident medical care. Your own Personal Injury Protection (PIP) coverage pays for accident-related medical visits, regardless of who caused the crash. To use those benefits, you must receive your initial medical evaluation within 14 days of the accident date.

A few practical points specific to concussions:

• The 14-day clock runs from the crash, not from the day your symptoms started. If you start having headaches on day five, you still have nine days left.

• Document everything from the first visit. Concussion is diagnosed primarily on the clinical exam, so a thorough first visit creates the record that supports the rest of your care.

• A clean PIP record helps follow-up care. If your concussion needs neurology follow-up, vestibular therapy, or imaging later, an established record makes that easier.

You can read more about how to keep your PIP record clean on our car accident PIP exam and documentation page.

What Happens at the Visit

A concussion evaluation does not take long. A typical visit at our walk-in clinic looks like this:

1. History. The medical doctor will ask about the crash, whether your head hit anything, whether you lost consciousness, what symptoms you have noticed, and when they started.

2. Neurologic exam. Pupil response, eye movement, balance, coordination, memory, and basic strength and sensation. This is the core of a concussion diagnosis.

3. Imaging when needed. Most concussions do not show up on imaging because the injury is at the cellular level. A CT scan may be ordered if there are concerning signs such as worsening headache, vomiting, or loss of consciousness. An MRI may be considered if symptoms persist.

4. Plan and return-to-activity guidance. A clear plan for rest, gradual return to work or school, when to follow up, and which symptoms should trigger an earlier return.

5. PIP documentation. Your visit is documented in the format your insurer expects, so your benefits are protected.

Imaging, when needed, can often be arranged the same day. See our overview of walk-in imaging for accident injuries for more on what we can read on site.

Recovery and Post-Concussion Syndrome

Most concussions improve within a few weeks. The first few days usually call for relative rest: limit screens, avoid heavy reading, hold off on workouts, and let your sleep schedule normalize. After that, doctors generally recommend a gradual return to activity, stopping or scaling back if symptoms return.

A meaningful minority of patients have symptoms that linger beyond the usual recovery window. When concussion symptoms continue for more than three months, the pattern is sometimes described as post-concussion syndrome. Persistent symptoms can include headache, dizziness, sleep problems, mood changes, and trouble with concentration.

A few things shorten and smooth out recovery:

• A real medical evaluation early, so you know what you are working with

• Sleep, hydration, and a steady routine

• Avoiding a second impact while you are still symptomatic

• A follow-up plan rather than a single visit

When Not to Wait

A few days of "I'll see if it gets better" is the most common reason concussions get missed. If you were in a crash, especially one with rear-end whiplash or any head contact, the safest step is a same-day evaluation while the details are still fresh and well inside your PIP window.

Our walk-in car accident injury clinic in Palm Beach County provides same-day concussion evaluations with medical doctors, on-site imaging when needed, and the documentation your PIP claim requires. No appointment is necessary, and most insurance is accepted.