Delayed Injury Symptoms After a Car Accident: What to Watch For

You were in a car accident and felt more or less fine. Now, hours or days later, something hurts: a headache, a stiff neck, ringing in your ears, or pain in your chest, stomach or back. If you’re wondering whether it’s worth a doctor’s visit, you’re asking the right question. Some crash injuries take time to show. The CDC says some concussion symptoms may not appear for hours or days, and MedlinePlus, the National Library of Medicine’s health site, says head injury symptoms can develop slowly over several hours or days. Any new symptom is a reason to see a doctor, and some need emergency care now.

This guide isn’t medical advice, and it can’t tell you what’s causing a symptom; only a doctor who examines you can. It shares what U.S. health agencies say to watch for, and why early medical records matter to a claim.

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When is a symptom after a car accident an emergency?

Call 911 or go to an emergency room right away for any of these signs after a crash. The CDC and MedlinePlus list each one as needing emergency care, and the sections below add more for specific symptoms:

• Head injury danger signs (CDC): 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; not recognizing people or places, or being confused, restless or agitated; or passing out, looking very drowsy or not being able to wake up. For a child who had a bump, blow or jolt to the head or body, the CDC adds crying that won’t stop and can’t be consoled, and not nursing or eating.
• Numbness or tingling (MedlinePlus) that starts just after a head, neck or back injury, or that comes with weakness or not being able to move. The same goes if you can’t control the movement of an arm or a leg, you’ve lost bladder or bowel control, you’re confused or have passed out, even briefly, or you have slurred speech, a change in vision, trouble walking or weakness.
• Chest pain (MedlinePlus): sudden crushing, squeezing, tightening or pressure in your chest; pain that spreads to your jaw, left arm or between your shoulder blades; nausea, dizziness, sweating, a racing heart or shortness of breath; sudden, sharp chest pain with shortness of breath, especially after a long trip, bed rest or other lack of movement, and especially if one leg is swollen or more swollen than the other; angina that is suddenly more intense, comes on with lighter activity, lasts longer than usual or occurs at rest; or a diagnosed serious condition such as a heart attack or pulmonary embolism.
• Belly pain (MedlinePlus) if you had a recent injury to your abdomen; your belly is tender, or rigid and hard to the touch; the pain is sudden and sharp; you’re vomiting blood or have blood in your stool; you have chest, neck or shoulder pain, or pain in or between your shoulder blades with nausea; you have difficulty breathing; you can’t pass stool, especially if you’re also vomiting; you’re pregnant or could be; or you’re being treated for cancer.
• Signs of shock or internal bleeding (MedlinePlus): confusion or decreasing alertness, clammy skin, dizziness or lightheadedness after an injury, low blood pressure, paleness, a rapid pulse, shortness of breath or weakness. Signs of internal bleeding may also include abdominal pain and swelling, chest pain, skin color changes, blood in your stool, urine or vomit, or vaginal bleeding that’s heavier than usual or comes after menopause. Internal bleeding can very quickly become life threatening.

If you’re having thoughts of suicide, call or text the 988 Suicide & Crisis Lifeline; in a life-threatening situation, call 911 (National Institute of Mental Health, NIMH).

Why are some injury symptoms delayed after a car accident?

Some injuries don’t cause symptoms right away, and some damage develops after the crash itself. Health agencies say this most clearly about brain injuries: some concussion symptoms may not appear for hours or days (CDC), and some brain injury symptoms can show up a few days or weeks later (MedlinePlus).

Some brain damage happens on impact, and some can develop gradually over hours, days or weeks, says the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health (NIH). Bruising or swelling of the brain, which generally happens when the head suddenly slows or stops, as in a high-speed car crash, can appear after a delay of hours to a day (NINDS). The head may look fine, but problems could result from bleeding or swelling inside the skull (MedlinePlus). NINDS tells people with a mild brain injury to watch for new symptoms, even ones that seem unrelated, because they may be related even several weeks after the injury.

Can a car wreck cause a concussion?

Yes. A concussion is a brain injury that happens when a hit to the head or body makes the head and brain move rapidly back and forth, and car accidents are one cause (MedlinePlus). Its symptoms may not start right away; they can begin days or weeks after the injury (MedlinePlus). For the claim side, see concussion and brain injury claims after a car accident.

Most people with a mild brain injury never pass out, and a person can have one and not realize it (MedlinePlus). The CDC lists concussion symptoms including headaches, dizziness, nausea, vision problems, being bothered by light or noise, feeling tired or foggy, trouble concentrating or remembering, irritability, anxiety, and sleeping more or less than usual. NINDS says every traumatic brain injury should be evaluated immediately by a professional who has experience with these injuries.

Why do I have a headache after a car accident?

A headache after a car accident can be a sign of a concussion, and MedlinePlus says to seek medical help right away when a headache occurs with a head injury. After a head injury, the CDC says to call 911 or go to an emergency department right away for a headache that gets worse and does not go away.

MedlinePlus also says to seek medical help right away for a headache that comes on suddenly and is explosive or violent (call 911 or go to the nearest emergency room); is “the worst ever,” even if you regularly get headaches; gets worse over 24 hours; comes with slurred speech, a change in vision, problems moving your arms or legs, loss of balance, confusion or memory loss, or with a fever, stiff neck, nausea and vomiting; is severe and just in one eye, with redness in that eye; or is the first headache you’ve ever had and interferes with your daily activities. Its list also includes headaches that have just started, especially if you’re older than 50; headaches with vision problems, pain while chewing or weight loss; a new headache if you’ve had cancer; and headaches when your immune system is weakened by disease or medicines.

Why are my ears ringing after a car accident?

Ringing in the ears after a car accident, called tinnitus, can follow a head or neck injury, which can damage the ear, the nerve that carries sound to the brain, or the parts of the brain that process sound (National Institute on Deafness and Other Communication Disorders, NIDCD, part of NIH). It can also be a concussion symptom, and MedlinePlus says to contact a provider if ear noises start after a head injury.

After an injury to the head, NINDS lists hearing problems such as ringing in the ears among the symptoms that call for immediate medical attention, especially in the first 24 hours. Tinnitus has also been linked to loud noise, and it can be a side effect of some medicines, including ibuprofen, naproxen and aspirin, especially at high doses (NIDCD), so tell the doctor what you’ve taken since the crash.

Why do I feel dizzy after a car accident?

Feeling dizzy after a car accident can be a concussion symptom (CDC), and lightheadedness can come from serious problems such as bleeding inside the body or shock (MedlinePlus). MedlinePlus says to call 911 or go to an emergency room if you’re dizzy and have a head injury, chest pain, shortness of breath, an irregular heart rate (your heart skipping beats), weakness, or an arm or leg you can’t move.

The same goes for dizziness with seizures, a change in vision or speech, fainting and loss of alertness for more than a few minutes, trouble keeping fluids down, or a fever over 101°F (38.3°C), a headache or a very stiff neck. Feeling faint and feeling the room spin (vertigo) are different symptoms, MedlinePlus explains, so tell the doctor which one you have and when it started.

Why does my neck hurt after a car accident?

Car accidents are a common cause of neck pain, including whiplash, a soft-tissue injury also called a neck sprain or strain (MedlinePlus). Accidents can also cause severe neck injuries, such as broken vertebrae (spine bones), blood vessel injuries and even paralysis, and MedlinePlus says to contact a provider when neck pain follows a fall, blow or injury. For the claim side, see whiplash and soft-tissue injury claims.

If you can’t move your arm or hand, have someone call 911 (MedlinePlus). Seek medical help right away for neck pain with symptoms of a heart attack, such as shortness of breath, sweating, nausea, vomiting, or arm or jaw pain, and call 911 or get to a hospital for a fever and headache with a neck so stiff you can’t touch your chin to your chest (MedlinePlus). MedlinePlus’s other reasons to contact a provider are numbness, tingling or weakness in your arm or hand; trouble swallowing or breathing with the neck pain; loss of bladder or bowel control; trouble walking and balancing; pain that gets worse when you lie down or wakes you up at night; pain so severe you can’t get comfortable; swollen glands or a lump in your neck; and symptoms that don’t go away in a week with self-care, or pain that doesn’t go away with regular doses of over-the-counter pain medicine. Neck pain can also be a concussion symptom, and concussion symptoms may start days or weeks after the injury (MedlinePlus).

Why does my shoulder hurt after a car accident?

Shoulder pain after a car accident can come from the shoulder itself, such as a broken bone, a dislocation or a torn rotator cuff, or it can be “referred” from a problem elsewhere, such as the neck or lungs (MedlinePlus). MedlinePlus says to go to an emergency room if you’ve just had a severe injury and your shoulder is very painful, swollen, bruised or bleeding.

Sudden left shoulder pain can sometimes be a sign of a heart attack: call 911 for sudden pressure or crushing pain in your shoulder, especially if the pain runs from your chest to your left jaw, arm or neck, or comes with shortness of breath, dizziness or sweating (MedlinePlus). A collapsed lung, which a rib fracture can cause, can also bring sharp chest or shoulder pain that gets worse when you breathe deeply or cough (MedlinePlus).

Why does my chest hurt after a car accident?

Chest pain or a sore chest after a car accident can come from any organ or tissue in the chest, including the ribs, muscles, lungs and heart, and MedlinePlus says some causes are serious and, in some cases, life threatening. Call 911 for sudden crushing, squeezing, tightening or pressure in your chest; pain that spreads to your jaw, left arm or between your shoulder blades; or chest pain with nausea, dizziness, sweating, a racing heart or shortness of breath (MedlinePlus). MedlinePlus also says to call 911 for sudden, sharp chest pain with shortness of breath, especially after a long trip, bed rest or other lack of movement, and especially if one leg is swollen or more swollen than the other; for angina that is suddenly more intense, comes on with lighter activity, lasts longer than usual or occurs at rest; or if you’ve been diagnosed with a serious condition such as a heart attack or pulmonary embolism.

An injury such as a rib fracture can also collapse a lung, causing sharp chest pain that gets worse with a deep breath or a cough, and shortness of breath (MedlinePlus). Chest pain can be a sign of internal bleeding, too (MedlinePlus). MedlinePlus says to check with a provider before treating most chest pain at home.

Why does my stomach hurt after a car accident?

Stomach pain after a car accident can be serious: MedlinePlus says to get medical help right away or call 911 for abdominal pain if you had a recent injury to your abdomen. Abdominal pain and swelling can be signs of internal bleeding, which MedlinePlus warns can very quickly become life threatening.

The same goes if your belly is tender, or rigid and hard to the touch; the pain is sudden and sharp; you vomit blood or have blood in your stool; you have chest, neck or shoulder pain, or pain in or between your shoulder blades with nausea; you have difficulty breathing; you can’t pass stool, especially if you’re also vomiting; you’re pregnant or could be; or you’re being treated for cancer (MedlinePlus). Blood in your urine can be another sign of internal bleeding (MedlinePlus). And don’t go by how much it hurts: how bad abdominal pain is doesn’t always reflect how serious its cause is (MedlinePlus).

Why does my lower back hurt after a car accident?

Lower back pain can start suddenly after an accident, and its causes range from strained or torn muscles and ligaments to a herniated disk or a broken bone in the spine (National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIAMS, part of NIH; MedlinePlus). NIAMS says to see a doctor for back pain after a fall or injury, and MedlinePlus says to contact your provider right away for back pain after a severe blow or fall.

Contact a provider right away, too, if you have weakness or numbness in your buttocks, thigh, leg or pelvis; pain traveling down your legs below the knee; loss of control over urine or stool; difficulty walking or keeping your balance; burning with urination or blood in your urine; pain that is worse when you lie down or wakes you up at night; severe pain that doesn’t let you get comfortable; redness or swelling on your back or spine; an unexplained fever with back pain; or a history of cancer (MedlinePlus). More generally, MedlinePlus says to get medical attention if you have back pain following an injury. If pain starts or gets worse days after the crash, tell your doctor when.

Why are my arms or legs numb or tingling after a car accident?

Numbness or tingling after a car accident can come from an injured nerve or pressure on the nerves of the spine, such as from a herniated disk: a neck injury can cause numbness along the arm or hand, and a low back injury along the leg or foot (MedlinePlus). MedlinePlus says to go to a hospital or call 911 if numbness or tingling starts just after a head, neck or back injury.

The same applies if numbness or tingling comes with weakness or not being able to move; you can’t control the movement of an arm or a leg, or you’ve lost bladder or bowel control; you’re confused or have passed out, even briefly; or you have slurred speech, a change in vision, trouble walking or weakness (MedlinePlus).

Can anxiety, nightmares or flashbacks start weeks after a car accident?

Yes. NIMH says PTSD symptoms usually begin within three months of a traumatic event, such as a serious accident, but they sometimes emerge later. A mental health professional can tell whether symptoms meet the criteria for PTSD (NIMH).

NIMH’s list of symptoms includes flashbacks, recurring memories or dreams about the event, being easily startled, feeling on edge and trouble sleeping; some people avoid driving or riding in a car after a serious crash. Anxiety, irritability and sadness can also be concussion symptoms (CDC), so mention emotional changes to your doctor, too. If you’re having thoughts of suicide, call or text 988 (NIMH).

New symptoms since the crash, and not sure what they mean for a claim? Get a free case review. Four quick questions, no cost, no obligation.

Should you see a doctor after a car accident if you feel fine?

Yes. Get checked promptly, even if you feel fine: some concussion symptoms may not appear for hours or days (CDC), and NINDS says every traumatic brain injury should be evaluated immediately. Your medical records are also the main proof of an injury claim.

The claims process runs on records and dates. The other driver’s insurer will need to determine whether your injuries are directly related to the accident, so it’s in your best interest to back up your claim with as much information as possible (Utah Insurance Department; Illinois Department of Insurance).

• Tell the doctor you were in a crash, describe every symptom, even minor ones, and keep your follow-up visits.
• Go back when something new shows up, and say when it started.
• Keep a short daily journal of your symptoms and what you couldn’t do, plus one folder for bills and records.
• Photograph visible injuries, such as bruises, and again as they change.

If cost is holding you back, see who pays your medical bills while your claim is pending. Our checklist of 10 things to do after a car accident covers the rest of the first week.

Can waiting to see a doctor hurt your car accident claim?

It can make your injury harder to prove. A gap between the crash and your first doctor’s visit, or a long break in treatment, lets an insurer argue that something else caused your symptoms: that’s an argument, not a rule of law, and records that start soon after the crash leave less room for it.

• Some benefits have treatment deadlines. As of September 2026, Florida’s no-fault personal injury protection (PIP) medical benefits require initial care within 14 days of the crash (Fla. Stat. § 627.736(1)(a)).
• A release usually ends the claim. A release gives up your right to sue, usually in exchange for payment (Cornell Law School’s Legal Information Institute). Signing one usually ends your claim for good, even if your injury turns out worse than you thought.
• Deadlines don’t wait for symptoms. The clock usually starts when you’re hurt, not when you learn how badly: in Michigan, a claim accrues when the wrong is done, regardless of when damage results (MCL 600.5827).

Tell your own insurer about the crash right away (California Department of Insurance). You have no contract with the other driver’s insurer (Texas Department of Insurance), so you don’t have to give it a recorded statement, and it’s safer not to before you’ve had advice. See what to say when an insurance adjuster calls.

What to do next

1. Get emergency care for any danger sign above. Otherwise, see a doctor promptly and say you were in a crash.
2. Report every new symptom and the day it started, and keep a symptom journal and one folder of records.
3. Tell your own insurer right away, and in Michigan, send written notice within one year of the crash.
4. Get advice before you give a recorded statement or sign a release. Get a free case review, or compare Michigan injury lawyers near you.

What waiting can cost

• Your health. After a head injury, the head may look fine, but problems could result from bleeding or swelling inside the skull, and internal bleeding can very quickly become life threatening (MedlinePlus).
• Your benefits. Michigan’s PIP notice is due within one year of the crash (MCL 500.3145(1)).
• The claim itself. A release signed too early usually ends it, and a lawsuit filed after the deadline can be dismissed, however strong the case (in Michigan, MCL 600.5805(1)).

What a good outcome looks like

Every new symptom gets checked, and anything that needs emergency care gets it right away. Your records show when each symptom started and that your doctor knew about the crash. Every notice goes out on time, and you settle only once you know how badly you were hurt. From wondering whether a new ache matters to knowing it’s checked, written down and inside every deadline.

For more, see our car accident lawsuit guide or the car, truck and motorcycle accident guides.

Updated September 25, 2026

This guide is general information, not legal advice, and laws change. For advice about your situation, talk to a lawyer licensed in your state. Reading this page or contacting us does not create an attorney-client relationship.