Symptoms guide · 9 min read
Concussion Symptoms: The Full Checklist and Red Flags
Concussion symptoms rarely arrive as one obvious problem. They arrive as a headache that won't settle, a room that tilts when you turn your head, a paragraph you've read three times, and a temper you don't recognize. Two people can take the same hit and walk away with two different lists.
This guide sets out the whole picture: the four groups clinicians sort symptoms into, the danger signs that mean emergency care tonight, the eye and vision problems that go unnoticed for months, how symptom scales turn all of it into a number you can track, and who to see when things aren't settling.
If you're reading this within hours of a head injury, skip to the emergency section below. The rest will keep until morning.
What are the symptoms of a concussion?
The symptoms of a concussion fall into four groups — physical, cognitive, emotional and sleep — and most people end up with some from each rather than all from one. A headache with fogginess, a short fuse and broken sleep is a far more typical presentation than a headache on its own.
The groups below follow the CDC's list of concussion signs and symptoms.
| Group | What it looks like | When people usually notice it |
|---|---|---|
| Physical | Headache or pressure in the head, dizziness, balance trouble, nausea, sensitivity to light and noise, neck pain, blurred vision, fatigue | Straight away, or the first time you stand up and move around |
| Cognitive | Fogginess, feeling slowed down, trouble concentrating, gaps in memory for the event, losing a word mid-sentence, needing longer to answer | Back at work, back at school, or twenty minutes into a screen |
| Emotional | Irritability, anxiety, low mood, crying more easily, feeling more emotional than usual | Several days in — and often noticed by someone else first |
| Sleep | Sleeping much more or much less than usual, trouble falling asleep, waking unrefreshed | Across the first week, as the pattern becomes obvious |
No single item on that list confirms a concussion, and no missing item rules one out. Losing consciousness isn't required either — ICD-10-CM carries a dedicated code for concussion without loss of consciousness. Diagnosis is clinical: a person takes a history and examines you. The American Congress of Rehabilitation Medicine published updated diagnostic criteria for mild traumatic brain injury in 2023 for exactly that reason.
When do concussion symptoms mean you need emergency care?
Get emergency care if a headache gets worse and does not go away, or if the person loses consciousness, looks very drowsy or cannot be woken up — the CDC names both as danger signs after a head injury. For a child, add two more: crying that will not stop and cannot be consoled, and refusing to nurse or eat.
These are not "bad concussion symptoms" to be watched at home. They are the signs that something an emergency department needs to look for may be present, and that is the entire reason the CDC danger-sign list exists. Don't wait to see whether it settles overnight.
One thing that surprises people: being sent home without a scan is usually the guideline being followed, not a brush-off. Summarizing the CDC pediatric guideline, American Family Physician states that head CT should not be routinely performed to assess patients with mild TBI. Imaging is how the danger list gets ruled out. It isn't how a concussion gets diagnosed.
What do mild concussion symptoms look like?
Mild concussion symptoms are the ordinary version of the list above — headache, fogginess, light sensitivity, dizziness, feeling a step behind — with none of the danger signs and usually no loss of consciousness. "Mild" classifies the injury, not your week.
That distinction does a lot of damage. A mild traumatic brain injury can leave someone unable to read a spreadsheet or stand in a supermarket aisle, and being told the injury was mild reads as being told the problem is small. It isn't the same statement. Mild is a category, not a promise.
In practice, the line you're watching for isn't mild versus severe on day one. It's the direction of travel: symptoms that ease week by week, versus symptoms that build, spread or stop responding to rest. The first is the expected course. The second is the reason to get seen again.
Why do some concussion symptoms take days to appear?
Because they genuinely can. The CDC is explicit that some symptoms may appear right away while others may not appear for hours or days after the injury.
Three things drive the delay. Adrenaline and the sheer distraction of an accident cover a lot in the first hour. Vestibular and visual problems are load-dependent — they only announce themselves when you go back to a busy store, a screen or a classroom, which for most people is day two or three, not day one. And sleep disruption compounds: one bad night is unremarkable, four in a row isn't. If you want the timing broken down properly, we've written a separate guide on how long after hitting your head symptoms can start.
Delayed onset is common. Delayed worsening — escalating headache, repeated vomiting, confusion, weakness, slurred speech, seizures, unusual drowsiness — is the emergency list above, not a late-blooming concussion symptom. Treat it accordingly.
What are concussion symptoms in the eyes?
Eye symptoms after concussion include blurred or doubled vision, words that swim or slide on the page, losing your place while reading, eye strain and headache that build the longer you look at a screen, and trouble switching focus between near and far. The most common identifiable cause is convergence insufficiency — the eyes not teaming up at close range — which a 2024 review found in 20.4% of patients with post-concussion syndrome, roughly one in five.
None of that shows up on a standard eye chart. Acuity testing asks whether you can see a letter at distance; it doesn't ask whether both eyes can hold a target at reading distance for twenty minutes without the sentence breaking apart. People are told their vision is fine and leave with the problem intact.
This is also where our own numbers are least comfortable. Across the 3,205 listings in our directory, vision and neuro-optometry is the thinnest widely-needed service in the country: 401 listings, against 1,067 offering vestibular and balance care. Worse, only 184 listings offer both under one roof — so most people with dizziness and reading trouble, which very often travel together, are looking at two appointments in two places rather than one visit. Plan for that when you're booking.
Be careful with promises here — though for one specific problem, the evidence recently caught up with the practice. In the CONCUSS randomized trial, immediate office-based vergence therapy left 88% of participants successful or improved against 8% with delayed treatment for concussion-related convergence insufficiency. Read that as narrowly as it was run: one eye-teaming problem, in 11-to-25-year-olds — not evidence that vision therapy treats fog, headache or mood, and any clinic stretching it further is ahead of the evidence. Our guide to concussion treatment options covers what the trials do and don't support.
How is a concussion symptom checklist scored?
The Post-Concussion Symptom Scale (PCSS) is a list of 22 symptoms, each rated from 0 (none) to 6 (severe), which produces a total score and a count of how many symptoms are present. A clinician reads the trend across visits, not a single day's number.
The items are the four groups above, broken into their parts: headache, pressure in the head, neck pain, nausea, dizziness, balance problems, sensitivity to light, sensitivity to noise, feeling slowed down, fogginess, difficulty concentrating, difficulty remembering, fatigue, confusion, drowsiness, irritability, sadness, nervousness, feeling more emotional, trouble falling asleep, sleeping more than usual, sleeping less than usual.
A few things a symptom scale is not. It is not a diagnosis — a high score doesn't confirm a concussion and a low one doesn't clear you. It is not a clearance test for sport or work. And it is easily distorted by comparing a score taken at 9am on a rested morning with one taken at 6pm after a full day of screens. Score it the same way, at the same time of day, and take the sheet with you to the appointment. It converts "still not right" into something a clinician can act on.
How long do concussion symptoms last?
Most people improve over days to weeks, and symptoms are formally called persisting beyond two weeks in adults and beyond four weeks in children. Passing those marks doesn't mean something has gone permanently wrong — it means the case has moved from watchful waiting to active management.
The numbers worth holding onto: up to 30% of children and adolescents still have symptoms at four weeks or longer, and 10 to 15% of adults have symptoms that persist beyond a year. That last group is small, real, and routinely told nothing is wrong.
When symptoms outlast those windows, the label changes — post-concussion syndrome, increasingly written as persisting post-concussive symptoms. We cover what that means and how it's managed in the guide to post-concussion syndrome, and the expected arc of an ordinary recovery in the stages of concussion recovery. Nobody can give you your own date. Anyone who offers one is guessing.
What should you do in the first two days after symptoms start?
Not lie in a dark room. The 2023 Amsterdam consensus statement holds that individuals can return to light-intensity physical activity during the initial 24–48 hours following a concussion, staying below the level that noticeably worsens symptoms.
The old advice — total rest until every symptom disappears — is gone, and the replacement is symptom-guided activity. In a 2019 randomized trial, adolescents given early sub-threshold aerobic exercise recovered in a median of 13 days versus 17 for a stretching group. That threshold can be set formally: the Buffalo Concussion Treadmill Test identifies a heart rate threshold of exercise tolerance in concussed patients, and is a separate tool from the trial above.
Light activity is not contact sport, and it is not pushing through. Anything that risks a second head impact stays off the table until a clinician clears it. Walking is usually where this starts.
Do children show different concussion symptoms?
The four groups are the same, but young children can't report them, so what you're watching is behavior: irritability and crying more than usual, refusing to nurse or eat, and changes in sleeping patterns are the signs the CDC lists for infants and toddlers. Their recovery windows are longer too — four weeks, not two.
School matters more than people expect. The CDC's position is that most children can return to school within 1 to 2 days of a concussion, with adjustments, rather than waiting at home until symptom-free. If you're working out what's normal for a toddler or a young child, the signs of concussion in kids and toddlers are set out separately, including the ones circulating online that no CDC or AAP page actually supports.
Availability is uneven, and we'd rather say so. Of the 3,205 listings we've verified, 602 state a pediatric or youth focus, and they're spread across 49 states — not Vermont, not Wyoming.
Who should you see for concussion symptoms?
Match the clinician to the symptom that's dominating, because there is no single concussion doctor. A guideline synthesis in Archives of Physical Medicine and Rehabilitation describes concussion care as interdisciplinary and individually tailored to a patient's symptom profile, drawing on vestibular, vision-oculomotor, behavioral health and cognitive rehabilitation.
Roughly: dizziness, motion sensitivity and balance trouble point to vestibular therapy; reading, focus and screen symptoms point to neuro-optometry or vision therapy; memory and concentration point to neuropsychology; mood and sleep point to behavioral health; and a headache that has taken over points to a headache clinic. A systematic review found that incorporating visual interventions and cervical manual therapy into early rehabilitation significantly reduced symptoms and time to return to sport.
If your symptoms cross several of those lines, look for one place that handles more than one. In our directory, 1,117 listings describe themselves as multidisciplinary concussion programs and 861 offer four or more service categories — enough that a single coordinated appointment is realistic in most of the country, if you know to ask for it.
You don't have to work out the specialist type on your own. Our two-minute specialist quiz takes your dominant symptoms and returns the type of clinician who handles them, then the verified providers near you. If you already know what you're looking for, search the directory by location and service — every listing is verified against the provider's own site, inclusion is free, and nothing is ranked by payment.
This guide is education, not a diagnosis. Symptoms that are worsening, or that haven't shifted after a couple of weeks, are worth a clinician's eyes rather than another week of waiting.
Find a concussion specialist near you
Search 3,205 verified concussion clinics and specialists across all 50 states — filter by services like vestibular therapy, vision therapy, and neuropsychology.
Browse the largest state directories: California (148) · South Carolina (136) · Pennsylvania (125).
Not sure which kind of specialist your symptoms point to? Take the 2-minute specialist quiz →
Frequently asked questions
Can you have a concussion without losing consciousness?
Yes. Loss of consciousness happens in only some concussions, and ICD-10-CM includes a specific code for concussion without loss of consciousness (S06.0X0A). Diagnosis rests on the clinical picture — the mechanism of injury, the symptoms and the examination — not on whether someone blacked out.
Do concussion symptoms show up on a CT scan?
Usually not, and that is expected. Guidance summarized by American Family Physician states that head CT should not be routinely performed to assess patients with mild TBI, because imaging is there to rule out the injuries behind the danger signs. Being sent home from an emergency department without a scan is often the guideline being applied correctly.
What are concussion symptoms in a toddler?
Young children cannot describe what they feel, so the signs the CDC lists for infants and toddlers are behavioral: irritability and crying more than usual, refusing to nurse or eat, and changes in sleeping patterns. Crying that will not stop and cannot be consoled, or refusing to eat at all, belongs on the emergency list rather than the watch-and-wait list.
Should you rest in a dark room until concussion symptoms go away?
No — that advice has been replaced. The 2023 Amsterdam consensus statement supports returning to light-intensity physical activity during the initial 24–48 hours, kept below the level that clearly worsens symptoms. Anything carrying a risk of a second head impact stays off until a clinician clears it.
What is the difference between concussion symptoms and post-concussion syndrome?
They are the same symptoms, measured against the clock. Symptoms are described as persisting beyond two weeks in adults and beyond four weeks in children, and that persisting picture is what gets labeled post-concussion syndrome, or persisting post-concussive symptoms. The change of name matters because it moves care from waiting to active, symptom-targeted management.
What should you bring to a concussion appointment?
A scored symptom list is the single most useful thing. Rate the 22 Post-Concussion Symptom Scale items from 0 (none) to 6 (severe), at the same time of day across several days, and note which activities make each one worse. That turns "still not right" into a pattern a clinician can act on.
Educational content only — not a substitute for professional medical advice, diagnosis, or treatment. Reviewed by Jon MacKay, PharmD, BCACP against current clinical guidance; last updated August 2026.