Key Takeaways
- Suspect a concussion when new physical, thinking, emotional, or sleep-related symptoms begin after a blow or jolt to the head or body.
- You can have a concussion without losing consciousness. Most people with concussions do not pass out.
- Common symptoms include headache, dizziness, nausea, balance problems, confusion, memory problems, light or noise sensitivity, and feeling mentally foggy.
- Worsening headache, repeated vomiting, seizure, weakness, unequal pupils, increasing confusion, unconsciousness, or difficulty waking requires emergency medical help.
- No home test can reliably diagnose or rule out a concussion. A healthcare professional should assess a suspected concussion.
You may have a concussion if new symptoms begin after hitting your head, falling, being involved in a collision, or experiencing a forceful movement that makes your head move rapidly.
Common symptoms include headache, dizziness, nausea, confusion, memory problems, balance difficulties, unusual tiredness, and sensitivity to light or noise. However, symptoms alone cannot confirm a concussion, and some warning signs may indicate a more serious injury such as bleeding inside the skull.
The first priority is to check for emergency warning signs. After that, a healthcare professional can assess whether the injury is likely to be a concussion and whether further testing is needed.
This article provides general information and is not a substitute for medical diagnosis or emergency care. Use your local emergency number and follow the advice of healthcare professionals in your country.
What Is a Concussion?
A concussion is a type of mild traumatic brain injury that affects how the brain functions. It can result from a direct impact to the head, but the head does not necessarily have to strike an object. A forceful blow to the body can also cause a concussion if it makes the head and brain move rapidly.
Falls, traffic collisions, sports injuries, bicycle accidents, workplace incidents, assaults, and impacts with hard objects can all cause concussions.
Not everyone who hits their head develops a concussion. Concern increases when the injury is followed by changes in how the person feels, thinks, behaves, moves, or sleeps.
Although many people improve within a few weeks, concussion symptoms can sometimes last longer. The term “mild” refers to the initial medical classification of the brain injury and does not mean that the symptoms should be ignored.
Check for Emergency Warning Signs First
Call your local emergency number or go to an emergency department immediately if the injured person:
- Has a headache that is worsening or will not go away
- Vomits repeatedly
- Has a seizure or convulsions
- Develops slurred speech or markedly unusual behavior
- Has weakness, numbness, or reduced coordination
- Has one pupil that appears larger than the other
- Cannot recognize familiar people or places
- Becomes increasingly confused, restless, or agitated
- Loses consciousness
- Becomes very drowsy or cannot be woken normally
These symptoms may indicate bleeding, swelling, or another serious brain injury rather than an uncomplicated concussion.
Emergency assessment may also be needed after a high-energy collision, a significant fall, a penetrating injury, visible skull damage, or blood or clear fluid coming from an ear or the nose.
Do not drive yourself to an emergency department if you are confused, dizzy, unusually tired, or having vision problems. If a neck injury is possible, avoid moving the injured person unnecessarily while waiting for emergency help.
When to Get Prompt Medical Advice
Even without emergency warning signs, seek prompt medical advice if the person has:
- Any episode of passing out, even if consciousness returned
- A gap in memory before or after the injury
- A persistent headache
- Vomiting after the injury
- A bleeding or clotting disorder
- Blood-thinning or antiplatelet medication
- A previous brain operation
- Alcohol or drug intoxication that makes symptoms difficult to assess
- Symptoms after a high-energy injury
- Behavior that is noticeably different from normal
Infants, young children, older adults, and people with previous brain injuries may require a lower threshold for assessment. Local referral and imaging rules vary, so contact an appropriate medical advice service when uncertain.
Common Signs and Symptoms of a Concussion
Concussion symptoms vary from person to person. One person may have an obvious headache and dizziness, while another may mainly notice concentration problems, irritability, or unusual fatigue.
Symptoms can affect how a person feels, thinks, behaves, and sleeps.
| Symptom category | Possible symptoms |
| Physical | Headache, dizziness, nausea, fatigue, blurred vision, balance problems, and sensitivity to light or noise |
| Thinking and memory | Feeling foggy or slowed down, poor concentration, confusion, memory gaps, and difficulty thinking clearly |
| Behavior and emotions | Irritability, nervousness, sadness, anxiety, unusual emotional reactions, or personality changes |
| Sleep | Sleeping more or less than usual, difficulty falling asleep, or changes in normal sleep patterns |
A single symptom does not necessarily mean that you have a concussion. A headache, for example, may also be caused by stress, dehydration, migraine, or a superficial injury.
A concussion becomes more likely when one or more new symptoms appear after a head impact or forceful jolt.
How to Check for a Possible Concussion
There is no reliable home test that can confirm or rule out a concussion. However, you can collect useful information for a healthcare professional.
First, consider what happened. Did the person hit their head, fall, collide with someone, experience a whiplash-like movement, or receive a forceful hit to the body? A visible bump or wound is not required for a brain injury.
Next, compare the person’s current condition with how they normally feel and behave. Watch for a new headache, dizziness, nausea, vision changes, light or noise sensitivity, balance problems, mental fogginess, slower thinking, memory gaps, or unusual tiredness.
Ask what the person remembers immediately before and after the injury. A gap in memory can be a sign of concussion. Another person may notice slow answers, repeated questions, unsteady walking, a dazed appearance, or behavior that is out of character.
Write down:
- When and how the injury happened
- Whether the person passed out
- Any memory loss, vomiting, or seizure
- Which symptoms developed and when
- Whether symptoms are improving or worsening
- Current medications, especially blood thinners
- Previous concussions or brain injuries
Do not perform difficult balance exercises, drive, exercise intensely, or return to sports to “test” whether you are fine. These activities can create a risk of falling or sustaining another head impact.
Simple orientation questions may reveal obvious confusion, but correct answers do not rule out concussion. Phone apps, online quizzes, home pupil checks, and balance tests cannot provide medical clearance.
Can Concussion Symptoms Be Delayed?
Yes. Symptoms can begin immediately, but they may also appear or become noticeable hours or days after the injury.
A person may initially feel reasonably well and later develop headache, concentration problems, irritability, sleep changes, light sensitivity, nausea, or unusual fatigue.
Symptoms can also become more apparent when regular activities resume. Reading, screen use, school, work, driving, exercise, bright light, or noisy environments may reveal difficulties that were not obvious during rest.
Feeling normal immediately after an impact does not completely rule out concussion. Continue watching for new or worsening symptoms and avoid activities that could lead to another head injury.
Can You Have a Concussion Without Passing Out?
Yes. Loss of consciousness is not required for a concussion, and most people with concussions do not pass out.
A person may remain awake, continue talking, or even finish an activity while having a concussion. Less dramatic symptoms—such as mental fogginess, headache, slow responses, memory problems, or light sensitivity—can be easy to overlook.
Any new change in neurological function after a head impact or forceful jolt should be taken seriously.
How Healthcare Professionals Diagnose a Concussion
A healthcare professional diagnoses a concussion by reviewing how the injury occurred, assessing symptoms, and performing a physical and neurological examination.
The clinician may ask about loss of consciousness, vomiting, seizures, memory loss, and when symptoms began. The examination may include alertness, speech, pupils, strength, sensation, coordination, balance, concentration, memory, and the ability to follow instructions.
There is no single test, scan, blood test, or questionnaire that identifies every concussion. Diagnosis depends on the combined history, symptoms, examination findings, and clinical judgment.
A CT scan is generally used to look for structural injuries such as bleeding or a skull fracture. It is not routinely needed for every suspected concussion and may appear normal when a concussion is present. Clinicians use the mechanism of injury, examination, age, symptoms, medications, and validated decision rules to determine whether imaging is appropriate.
What to Do After a Possible Concussion
Stop the activity that caused the injury. Avoid sports, heavy exercise, driving, cycling, operating machinery, climbing ladders, and other activities in which poor balance or slower reactions could cause another accident.
A responsible adult should ideally stay with the injured person during the first 24 hours. The observer should watch for worsening headache, repeated vomiting, increasing confusion, unusual behavior, weakness, seizures, unconsciousness, or difficulty waking. Home observation should not replace medical assessment when symptoms or risk factors indicate that care is needed.
It is usually acceptable to sleep after a minor head injury when no emergency warning signs are present. You do not need to force someone to remain awake simply because a concussion is possible. However, someone who cannot be woken normally needs emergency help.
During the first one or two days, use relative rest. Reduce activities that noticeably worsen symptoms, but do not remain isolated in a dark room or avoid all mental and physical activity for an extended period.
After one or two days, gradually resume light daily activity, such as a short walk, as tolerated. If an activity causes a significant increase in symptoms, reduce its intensity or duration and try again more gradually.
Avoid alcohol, recreational drugs, and sedating medication unless a healthcare professional says it is safe. Ask a clinician or pharmacist which pain medicines are appropriate, particularly if there is a possibility of bleeding or the person takes other medication.
Returning to School, Work, Driving, and Sports
A healthcare professional can provide individualized guidance for returning to school, work, driving, exercise, and other activities.
Do not drive while you have dizziness, vision problems, severe tiredness, confusion, slowed reactions, or difficulty concentrating.
Students may initially need shorter school days, rest breaks, reduced screen exposure, extra time for assignments, or temporary limits on tests. Returning gradually is usually preferable to prolonged total absence when symptoms allow.
An athlete with a possible concussion should be removed from play immediately and must not return on the same day.
Return to sport should occur only after healthcare approval and through a supervised, stepwise progression. Each stage generally takes at least 24 hours. If symptoms return, the athlete should stop, contact the supervising healthcare professional, and resume at an earlier stage after further recovery.
How to Recognize a Concussion in a Child
Concussion can be more difficult to recognize in babies and young children because they may not be able to describe dizziness, mental fogginess, or light sensitivity.
Possible signs include:
- Appearing dazed
- Crying more than usual
- Unusual irritability
- Loss of interest in favorite activities
- Unsteady walking
- Changes in eating or sleeping
- Vomiting
- Tiring more easily
- Behavior that is noticeably different from normal
Parents and caregivers should focus on changes from the child’s usual behavior.
Seek emergency help for the warning signs listed earlier. Emergency assessment is also needed if a child cannot be comforted, refuses to nurse or eat, has a seizure, becomes increasingly drowsy, or cannot be woken normally.
A large or rapidly increasing area of swelling on an infant’s head also requires prompt medical assessment.
How Long Do Concussion Symptoms Last?
Recovery varies from person to person. Most people improve over time and many feel better within a couple of weeks, but some experience symptoms for longer.
Recovery may be slower in young children, older adults, and people with previous concussions or other medical conditions. Sleep, mental health, migraines, injury history, and the demands of school, work, or sport may also affect the recovery experience.
Do not use the disappearance of a headache as the only measure of recovery. Concentration, balance, reaction time, sleep, and tolerance of physical activity may improve at different rates.
Contact a healthcare professional if symptoms:
- Are worsening rather than improving
- Interfere substantially with school, work, sleep, or daily activities
- Return strongly whenever activities resume
- Have not resolved or clearly improved within two to three weeks
Some people need referral to a clinician or rehabilitation team experienced in managing persistent concussion symptoms.
Frequently Asked Questions
Should I avoid screens completely after a possible concussion?
Complete screen avoidance is not usually necessary. During the first one or two days, reduce phone, computer, television, and gaming use if these activities clearly worsen symptoms. Gradually increase screen time as tolerated.
When is it safe to drive after a concussion?
Do not drive while you have dizziness, vision problems, confusion, slowed reactions, unusual fatigue, or difficulty concentrating. Ask a healthcare professional when you can safely resume driving if symptoms continue.
Can someone with a possible concussion be left alone?
Many head-injury guidelines recommend that a responsible adult stay with the person for the first 24 hours. The observer should know the emergency warning signs and how to obtain help.
What information should I give the healthcare professional?
Explain how and when the injury happened, whether there was loss of consciousness or memory loss, whether the person vomited or had a seizure, which symptoms developed, and whether they are improving or worsening. Also provide a complete medication list and information about previous brain injuries.
Why do symptoms return when I resume normal activities?
Mental or physical activity may temporarily make symptoms more noticeable during recovery. Reduce the activity to a tolerable level and increase it gradually. Contact a healthcare professional if symptoms worsen significantly or repeatedly.
What happens if I receive another head impact before recovering?
A second head impact can worsen symptoms and prolong recovery. Avoid sports and other activities with a risk of another head injury until a healthcare professional says that it is safe to return.
