- A concussion is a mild traumatic brain injury (TBI) from a bump, blow, or jolt to the head or body; loss of consciousness is NOT required for a concussion to have occurred.
- Call 911 or go to the ER for red flags: repeated vomiting, a worsening or severe headache, a seizure, unequal pupils, weakness or numbness, slurred speech, neck pain, or someone who is increasingly confused, drowsy, or cannot be woken — especially anyone on blood thinners.
- Never return to sports or vigorous activity the same day as a suspected concussion; a second hit before recovery can cause rare but catastrophic second-impact syndrome, so "when in doubt, sit them out."
- Recovery uses a brief period of relative rest (24–48 hours), then a gradual, symptom-guided return to learning and activity — prolonged strict rest in a dark room is outdated and can slow recovery.
- Most people recover within about 1–4 weeks, but a meaningful minority have symptoms lasting longer and benefit from targeted care at a concussion clinic.
- This is general education, not medical advice; any suspected concussion should be evaluated by a clinician, and emergency symptoms need emergency care.
A concussion is a mild traumatic brain injury (TBI) caused by a bump, blow, or jolt to the head — or a hit to the body that makes the brain move rapidly inside the skull. Estimates suggest millions of concussions occur in the United States each year from sports and recreation, falls, motor vehicle crashes, and assaults, per the CDC. The reassuring news is that most concussions resolve within about 1 to 4 weeks; the harder reality is that a meaningful minority have symptoms lasting months, and outdated advice — “rest in a dark room until you feel better” — can actually slow recovery. This article is general education, not medical advice; any suspected concussion should be evaluated by a clinician, and the emergency symptoms below need emergency care right away.
After any head injury, call 911 or go to the nearest emergency room if the person has: repeated or forceful vomiting; a headache that is severe or keeps getting worse; a seizure or convulsion; unequal pupils (one bigger than the other); weakness, numbness, or decreased coordination; slurred speech or trouble understanding speech; clear fluid or blood draining from the nose or ears; neck pain; unusual or increasing confusion, agitation, or drowsiness; or someone who cannot be woken. Anyone taking blood thinners (anticoagulants) or with a bleeding disorder should be evaluated even after a seemingly minor head injury, because dangerous bleeding around the brain can develop slowly. When in doubt, get emergency care.
What Happens in the Brain
A concussion produces a metabolic and functional disturbance in brain cells, typically without visible structural damage on a standard CT scan. Rapid head acceleration and deceleration stretch nerve fibers (axons) and trigger an energy crisis as the brain works overtime to restore normal cell function. This period of metabolic vulnerability lasts roughly 7 to 10 days, which is part of why a second hit during this window is far more dangerous than a similar hit after full recovery.
Loss of consciousness is not required for a concussion — only a small minority of concussions involve any loss of consciousness. Confusion, a dazed or “stunned” appearance, memory gaps around the event, or simply feeling “off” after a hit are equally telling. Because of this, a concussion is easy to miss if you assume someone is fine just because they never blacked out.
Symptoms Often Evolve Over Hours
Symptoms typically fall into four groups: physical (headache, dizziness, nausea, balance problems, sensitivity to light or noise), cognitive (slowed thinking, difficulty concentrating, memory problems, “brain fog”), emotional (irritability, sadness, anxiety, feeling more emotional than usual), and sleep-related (sleeping more or less than usual, trouble falling asleep).
Importantly, symptoms can appear immediately or emerge over the following 24 to 48 hours, so someone who seems okay right after a hit can worsen later — which is why they should not be left alone overnight after a significant injury. Children and teenagers may not describe symptoms clearly; parents, coaches, and teachers should watch for unusual quietness, avoiding bright or loud environments, complaints of headache, balance issues, or simply not seeming themselves. The MedlinePlus and CDC HEADS UP materials emphasize that concussion symptoms can fluctuate during early recovery and tend to worsen with cognitive or physical exertion.
Remove From Play — and No Return the Same Day
This is the single most important safety rule in sports: any athlete with a suspected concussion must be removed from play immediately and must not return to games, practice, or vigorous activity the same day. This is the consistent recommendation of the American Academy of Neurology (AAN) and the international Concussion in Sport Group. “When in doubt, sit them out” — even if symptoms seem mild or the athlete insists they are fine.
The reason is second-impact syndrome: on rare occasions, a second concussion suffered before the brain has recovered from the first can trigger catastrophic, sometimes fatal brain swelling. It has been reported almost exclusively in adolescents and young adults, and it is the most cited reason for strict return-to-play protocols. No game or competition is worth that risk. An athlete should only begin the return-to-play process after being evaluated and cleared to start, and only under the guidance of a clinician familiar with concussion.
When Imaging Is Needed
Most concussions do not require a CT scan. Validated decision rules — such as the Canadian CT Head Rule, the New Orleans Criteria, and PECARN for children — help clinicians identify who actually needs imaging. Indications include loss of consciousness, repeated vomiting, a severe or worsening headache, focal neurological deficits, suspected skull fracture, a dangerous mechanism (a high-speed crash or a fall from significant height), older age, or use of anticoagulants. These overlap with the emergency red flags above.
MRI is more sensitive for subtle injuries but is rarely needed in the acute phase. Symptoms persisting well beyond a month occasionally prompt MRI to rule out other structural problems, though imaging is usually unrevealing in concussion. Our broader traumatic brain injury guide covers imaging in moderate and severe injuries.
Recovery: What Actually Helps
Older guidance to rest in a dark room for days or weeks has been replaced by evidence-based protocols. Current consensus recommends 24 to 48 hours of relative rest — not total isolation — followed by a gradual reintroduction of light cognitive and physical activity kept below the level that clearly worsens symptoms. Prolonged strict rest (“cocooning”) can actually prolong recovery and worsen mood.
Light aerobic activity at a sub-symptom-threshold intensity, started within the first week under appropriate guidance, has been shown in multiple randomized trials to speed recovery in adolescents and adults. This is a genuine paradigm shift from the old “complete rest until symptom-free” advice, and it should be done gradually and, ideally, with clinician direction rather than pushed to the point of provoking symptoms.
Hydration, regular sleep, and a balanced diet support recovery. Avoiding alcohol and recreational drugs during recovery is recommended. For headache, over-the-counter pain relievers are sometimes used, but which medication is appropriate — and whether to use it at all in the first day or two — is a decision for a clinician or pharmacist, particularly for anyone on blood thinners; this article does not provide dosing. If headaches are severe, worsening, or accompanied by any red-flag symptom, seek emergency care rather than treating at home.
Return-to-Learn and Return-to-Play
Recovery uses two parallel, stepwise pathways: return-to-learn (school and work) and return-to-play (sport). Return-to-learn usually comes first, because most students return to full academics before returning to full contact sport. Accommodations may include reduced screen time, extended deadlines, breaks during testing, quiet rooms, and partial school days, easing back as symptoms allow.
For sport, athletes follow a graduated return-to-play protocol. After symptoms have settled at rest, they progress through stages — light aerobic activity, sport-specific exercise, non-contact training drills, full-contact practice after medical clearance, and finally competition — spending at least 24 hours at each stage. If symptoms recur at any stage, the athlete drops back to the previous stage and tries again later. The full progression means a return to contact sport takes, at minimum, several days after symptoms resolve, and often longer. Most U.S. states now have laws requiring concussion protocols for school athletes, including removal from play and clearance before return.
Persistent Post-Concussive Symptoms
A subset of concussion patients — often cited around 10 to 30 percent — have symptoms lasting beyond about 4 weeks, a condition variously called persistent post-concussive symptoms or post-concussion syndrome. Risk factors include female sex, a history of prior concussions, a history of migraine, a learning disability, pre-existing anxiety or depression, and the severity of the initial symptoms.
Persistent symptoms often cluster into specific subtypes — vestibular (dizziness, motion sensitivity), oculomotor (visual fatigue, difficulty reading), cervicogenic (neck-related headache), cognitive, mood/anxiety, or migrainous. Importantly, targeted treatment tends to work better than generic rest. Vestibular and vision therapy, cervical (neck) physical therapy, cognitive behavioral therapy, and structured headache management all have evidence in this population.
Most patients with persistent symptoms recover within about 6 months with appropriate care. Symptoms lingering beyond a year are uncommon but real and warrant comprehensive, multidisciplinary care, typically through a specialized concussion clinic. Persistent symptoms are a reason to seek more care, not to give up on recovery.
Repeat Concussions and Long-Term Concerns
On average, each subsequent concussion tends to take longer to recover from. Having three or more concussions is associated with somewhat higher rates of memory complaints and depression in some studies. The long-term risk of chronic traumatic encephalopathy (CTE) is most clearly linked to former contact-sport athletes with extensive cumulative exposure to repetitive head impacts, including sub-concussive impacts that do not produce obvious symptoms. Research in this area is still evolving, and CTE can currently only be diagnosed definitively after death, so individual risk is hard to quantify — but reducing unnecessary head impacts is sensible.
When to See a Doctor
Any suspected concussion warrants medical evaluation, even without red flags. Primary care physicians, urgent care clinicians, sports medicine doctors, and pediatricians all manage straightforward concussions. Seek care sooner rather than later if symptoms are significant, and go to the emergency department immediately for any of the red flags listed at the top of this article.
Symptoms persisting beyond about 2 to 4 weeks deserve referral to a concussion specialist or a comprehensive concussion clinic, where multidisciplinary care can address headaches, vision and vestibular issues, mood, and cognitive symptoms. A workup of persistent symptoms may include a detailed history, a neurological exam, vestibular and oculomotor testing, a neck assessment, mood screening, and sometimes formal neuropsychological testing. Our medical conditions overview covers when specialty referral makes sense across a range of chronic problems.
Frequently Asked Questions
How long does a concussion last?
Most concussions resolve within about 1 to 4 weeks, with adolescents often taking slightly longer than adults. Roughly 10 to 30 percent of patients have symptoms lasting beyond 4 weeks, and the large majority fully recover within 3 to 6 months with appropriate management. Recovery is guided by symptoms, not a fixed calendar.
Can you sleep after a concussion?
Yes. The old advice to wake someone every few hours has generally been retired. After an initial evaluation has ruled out serious injury, sleep is restorative and helps recovery. The exception is when a clinician specifically instructs monitoring for evolving symptoms — which is less common than it once was. If you notice any red-flag symptom, seek emergency care rather than waiting.
What is the difference between a concussion and a TBI?
A concussion is the most common form of mild traumatic brain injury. The terms overlap: “concussion” is typically used for milder injuries, while “TBI” is the broader umbrella term that also includes moderate and severe brain injuries. All concussions are TBIs; not all TBIs are concussions.
Can you exercise after a concussion?
Yes, with appropriate, gradual progression — but not the same day as the injury. Current guidelines support light, sub-symptom-threshold aerobic activity within the first week, ideally with clinician guidance. Strict prolonged rest is no longer recommended. Returning to contact sport, however, follows a structured, stepwise protocol and requires medical clearance before full-contact participation.
Is it safe to return to play if symptoms are mild?
No. An athlete with any suspected concussion should be removed from play and should not return the same day, regardless of how mild the symptoms seem. Return to sport happens later, in stages, after symptoms resolve and a clinician clears the athlete — because of the rare but catastrophic risk of second-impact syndrome.
What to Do Next
After a head injury, the immediate priority is checking for red flags — call 911 or go to an ER if any emergency symptom appears. If an athlete is involved, remove them from play and do not let them return the same day. For a straightforward concussion, 24 to 48 hours of relative rest, prompt medical evaluation, and a gradual, symptom-guided return to learning and activity produce the best outcomes for most people. Athletes should follow a stepwise return-to-play protocol overseen by a clinician. Anyone with symptoms persisting beyond 2 to 4 weeks should ask about referral to a comprehensive concussion clinic, where targeted vestibular, vision, cervical, and cognitive therapies often resolve symptoms that simple rest will not.
Medical disclaimer: This article is general education, not medical advice, and it does not provide medication dosing. A concussion is a brain injury: any suspected concussion should be evaluated by a qualified clinician. Call 911 or go to the nearest emergency room for red-flag symptoms — repeated vomiting, a severe or worsening headache, a seizure, unequal pupils, weakness or numbness, slurred speech, neck pain, fluid draining from the nose or ears, or increasing confusion, drowsiness, or inability to wake someone — and especially for anyone on blood thinners after a head injury. Never return to sports or vigorous activity the same day as a suspected concussion. For a suspected poisoning or medication overdose, call Poison Control at 1-800-222-1222. Do not delay emergency care to read or search online.
Sources
- Centers for Disease Control and Prevention (CDC) — HEADS UP concussion program and Traumatic Brain Injury pages (signs and symptoms, danger signs/red flags, and return-to-activity guidance)
- MedlinePlus (U.S. National Library of Medicine) — Concussion and Traumatic Brain Injury
- American Academy of Neurology (AAN) — evidence-based guideline on the evaluation and management of concussion in sports (immediate removal from play, no same-day return, graded return)
- Concussion in Sport Group — Amsterdam consensus statement (relative rest followed by sub-symptom-threshold activity; graded return-to-sport and return-to-learn protocols)