Do I Have a Concussion? Signs, Symptoms, and What to Do in the First 24 Hours

You hit your head. Or maybe your kid took a hard fall, your partner got rear-ended, or you took a soccer ball to the face. Now you are sitting there asking yourself the same question almost every concussion patient asks first: do I have a concussion, and what am I supposed to do right now?

Here is the calm version. A concussion is a real, common injury, but it is not usually a brain bleed and it is not usually a permanent injury. What it is, is a temporary disruption in how brain cells are working. The right moves in the first 24 hours can make recovery faster, safer, and far less stressful. The wrong moves, mostly waiting too long or trying to “tough it out,” can make things worse. This guide walks you through the signs of a concussion, the most common concussion symptoms, the head injury symptoms that need an emergency room, and a clear concussion checklist for what to do in the first day.

What Is a Concussion?

A concussion is a mild traumatic brain injury caused by a force to the head, neck, or body that shakes the brain inside the skull. It is a real injury, but it is what doctors call a functional injury, meaning the brain cells stop working properly for a while, even though a CT or MRI scan usually looks normal [1][2]. About one in every hundred people in the United States and Canada is diagnosed with a concussion each year, and that number is almost certainly an underestimate because many people never go in to be seen.

The Complete Concussions clinical model treats concussion as an energy and signaling problem in the brain. When the brain is jolted, brain cells fire all at once, calcium floods in, and the cell’s tiny energy factories (called mitochondria) get overwhelmed. The result is a short-term energy crisis. That energy crisis is why your brain can feel foggy, slow, or off, even when scans look fine [3][4]. It also explains why some symptoms do not show up right away, and why pushing too hard too soon can stall recovery.

What Are the Most Common Concussion Symptoms?

The most common concussion symptoms fall into four groups: physical, thinking, mood, and sleep. Headache and feeling “off” or “in a fog” are the two most common. Most people experience several symptoms at once rather than only one.

Common physical symptoms include:

• Headache or pressure in the head
• Dizziness or feeling unbalanced
• Nausea or, less often, vomiting
• Blurred or double vision
• Sensitivity to light or noise
• Ringing in the ears
• Feeling slowed down or sluggish

Common thinking and mood symptoms include:

• Trouble concentrating
• Trouble remembering what just happened
• Feeling foggy or “not yourself”
• More emotional than usual, easily frustrated, more anxious, or sad
• Trouble finding words or following a conversation

Common sleep symptoms include:

• Trouble falling asleep
• Sleeping more than usual
• Trouble staying asleep
• Waking up feeling unrested

A large study of nearly 600 athletes found that a total symptom score of about 7 or higher on a standard symptom checklist was strongly associated with having a concussion [5]. A 2024 diagnostic meta-analysis of common concussion assessment tools confirmed that symptom-based and standardized clinical tests still outperform any single test used alone [6]. You do not need a checklist at home to know something is wrong, but it is a useful reminder that a cluster of symptoms is more meaningful than any single one.

If you are within 48 hours of a head impact and the symptoms above feel familiar, treat it as a probable concussion until a trained clinician tells you otherwise. Complete Concussions-certified clinicians offer rapid access, often within 24 to 48 hours, with objective testing and a clear step-by-step plan from day one.

What Are the Signs of a Concussion You Can See in Someone Else?

Not all signs of a concussion are felt by the injured person. Some are easier for a bystander, parent, coach, or teammate to spot. These observable signs of a concussion include lying motionless after impact, looking dazed or stunned, a blank or vacant stare, slow to get up, balance problems or stumbling, slurred or slow speech, confusion about where they are or what just happened, repeating the same questions, and a brief loss of consciousness.

In video reviews of NFL games, observable visual signs were present in roughly three out of four diagnosed concussions, and the two most common were being slow to get up and motor incoordination [1]. If you see any of these after a hit, treat that person as concussed until proven otherwise. Pull them out of the game, the activity, or the driving seat, and keep watching them.

What Are the Signs of a Mild Concussion?

This is one of the most misunderstood parts of concussion. The mild concussion signs people miss most often are the quiet ones: a mild headache that did not exist before the hit, feeling foggy or slowed, a little dizziness when standing up, mild nausea, sensitivity to light or noise, sleep that feels off, and feeling more emotional than usual.

You do not need to lose consciousness to have a concussion. In fact, the large majority of concussions happen without loss of consciousness [1]. You also do not need to vomit, see stars, or hit the ground hard. If you took a meaningful force to the head, neck, or body and you feel even a few of the symptoms above, it is reasonable to treat it as a mild concussion and act accordingly.

The grading systems people remember from years ago, like “grade 1, 2, or 3,” have been abandoned because they did not actually predict recovery [1]. A so-called “mild” concussion can still take weeks to recover. That is why the focus has shifted to symptom patterns and proper management, not severity labels.

What Are the Most Common Head Injury Symptoms vs. a Concussion?

This is a key distinction. Head injury symptoms can range from a scalp bruise that needs nothing more than ice, all the way to a brain bleed that needs surgery. A concussion sits in the middle: a real injury to brain function, but usually not a structural injury visible on imaging.

A bump, cut, or bruise on the scalp without symptoms in the brain or nerves is usually not a concussion. A scalp injury combined with confusion, memory loss, repeated vomiting, severe or worsening headache, neck pain, weakness or numbness, double vision, seizure, or loss of consciousness is a different category and needs the emergency room right away [1].

Imaging is not the right tool to diagnose most concussions. Less than 1% of concussions show up on a standard MRI, and CT scans are designed to look for bleeds and fractures, not the temporary cell dysfunction that causes concussion symptoms [1]. A normal scan does not mean you do not have a concussion. It just means you do not have the dangerous structural injuries that scans are designed to find.

Why Do Some Concussion Symptoms Show Up Hours or Days Later?

Delayed concussion symptoms are common and they are not a sign that something is being missed. After the initial impact, the brain goes through two phases. First is a brief electrical storm, where lots of brain cells fire at once. Then comes a longer low-energy phase, called the metabolic recovery phase, where the brain is running on less fuel than usual [3][4]. That second phase can take weeks to fully resolve, even in adults whose symptoms feel mostly gone.

This is why someone can feel fine right after a hit, walk off the field, and then feel a headache build over the next hour, get nauseous on the drive home, struggle to focus the next morning, or feel “off” for several days. Amsterdam consensus guidance and clinical experience both note that signs and symptoms can be immediate or can evolve over minutes to hours [1]. A useful rule for parents, coaches, and partners: if there was a meaningful impact, plan for at least 24 to 48 hours of close observation before deciding “nothing happened.”

For families navigating this, the difference between good and poor concussion management matters. A Complete Concussions-certified provider can give you a proactive, evidence-based plan rather than a “wait and see” letter.

When to Go to the ER: Concussion Red Flags

Most concussions do not need an emergency room. But some head injuries do, and the difference matters. The international consensus statement on concussion in sport identifies a clear list of red flags that mean stop, do not pass go, and get to the nearest emergency department right away [1][7].

Go to the emergency room immediately if you or the person you are caring for has any of the following after a head impact:

• Loss of consciousness lasting longer than a brief moment
• Severe or rapidly worsening headache
• Repeated vomiting (more than once or twice)
• Seizure or convulsion
• Slurred speech, weakness, or numbness in the arms or legs
• Double vision that does not clear
• Increasing confusion or agitation
• A neck that is very painful or feels unstable
• Clear fluid or blood from the nose or ears
• A visible deformity of the skull
• The person becomes harder to wake up

Children, older adults, anyone on blood thinners, and anyone with a known bleeding disorder should have a lower threshold to be checked. If you are not sure, err on the side of being seen.

What to Do After Hitting Head: The First 24 Hours

If there are no red flags, you do not need an emergency room. What you need is a calm, structured first 24 hours concussion plan, and then a plan for the rest of the week. Here is what the evidence actually supports.

Stop the risky activity. Do not return to play, work that involves heavy machinery, driving, contact sport, cycling, or anything else where another hit could happen. A second concussion before the brain has recovered from the first is the most dangerous part of this injury [1].

Take it easy, but do not lie in a dark room. Old advice told concussion patients to rest completely until symptoms cleared. The current evidence is clear: prolonged strict rest is outdated and often makes things worse [1][8][9]. Relative rest for the first 24 to 48 hours is what is recommended, meaning gentle activity at home, light walks, and avoiding anything that significantly worsens symptoms.

Limit screens early, but do not go to extremes. A 2021 randomized clinical trial found that 48 hours of strict screen abstinence shortened recovery compared with unlimited screen use [10]. More recent evidence has nuanced this finding. Total avoidance of screens is not necessarily the goal, and complete blackout may even be counterproductive for mood, sleep, and social connection. The middle ground is best: cut screen time meaningfully in the first 24 to 48 hours (short check-ins rather than long scrolling sessions, no high-stimulation gaming, and breaks before symptoms worsen), then gradually expand use as you tolerate it.

Prioritize sleep and food. Sleep is one of the main ways the brain restocks its energy supply. Eat regular meals with protein and vegetables, drink water, and avoid alcohol completely for at least the first week. Alcohol after a concussion makes symptoms worse and slows healing.

Start moving the next day. Once you are past the first day or two, light walking, gentle daily activity, and breathing exercises become beneficial, not only safe. A meta-analysis of 24 youth concussion studies found that activity-based approaches improved symptom recovery compared to extended rest [8]. A large multi-site study of collegiate athletes found that earlier exercise was associated with faster recovery [11].

Get assessed by a concussion-trained clinician early. Recent evidence is consistent on this point. A 2024 study of more than 800 adolescents found that those evaluated in a specialty clinic within 48 hours recovered faster than those seen later in the first week [12]. A 2025 cohort study of nearly 4,700 Canadian adolescents found that early care seekers recovered in a median of 18 days, versus 22 days for late care seekers [13]. Earlier specialty care is one of the few changes that consistently shortens recovery.

A First-24-Hours Concussion Checklist

If you only remember one section of this article, remember this concussion checklist:

1. Stop the activity. Get away from any risk of a second hit.
2. Check for red flags. If any are present, go to the emergency room.
3. Have someone with you for at least the first few hours.
4. Stay hydrated and eat something.
5. Avoid alcohol and recreational substances completely.
6. Cut screen time meaningfully for 24 to 48 hours, but do not go fully dark. Short check-ins are fine; long scrolling and gaming are not.
7. Prioritize sleep, but you do not need to be woken up every hour. Normal sleep is fine.
8. Do gentle daily activities and short walks as tolerated.
9. Do not drive until symptoms are clearly better and a clinician has cleared you.
10. Book an appointment with a Complete Concussions-certified clinician as soon as possible, ideally within the first 24 to 48 hours.
11. Keep a simple log of your symptoms each morning and night, rated out of 10.
12. Tell your school, employer, or coach. Do not try to push through without telling someone.

This list works for adults, teens, and parents managing a child’s concussion. The details adjust by age, but the principles do not change.

Should You Try to “Sleep It Off”?

This is one of the most common questions from worried parents and partners. The short answer is yes, sleep is helpful, and no, you do not need to wake the person up every hour. That advice was based on a fear of missing a brain bleed, which is what red flag screening and emergency room evaluation are actually for [1][7]. If red flags are absent and the person is acting normally before bed, normal sleep is appropriate, and good sleep helps the brain recover [14].

What you should not do is treat sleep as the whole plan. Two days of sleep and limited screens is not concussion care. It is a starting point. Recovery comes from a combination of relative rest in the first 48 hours, then gradual return of light cognitive and physical activity, early assessment by a trained clinician, and targeted treatment if symptoms are not improving by the end of the first week [1][9][15].

What If Symptoms Are Not Better in a Few Days?

For most people, symptoms start improving within a few days to two weeks, and a typical adult or athlete is back to most normal activities within about three to four weeks [1][15]. That said, somewhere between 15% and 30% of people develop symptoms that last longer than a month [16]. People with pre-existing anxiety, prior concussions, high initial symptom severity, or a delay in getting trained care are at higher risk of slower recovery [16][17][15].

If your symptoms are not clearly improving by day 7 to 10, that is not a sign to wait longer. It is a sign to get evaluated, ideally by a clinician trained in concussion. Multidomain assessment, looking at the neck, vestibular system, vision, autonomic function, sleep, and mood, can identify which systems are driving the persistent symptoms. Once the drivers are known, targeted rehabilitation can be started, and most people respond well [1][14][7].

A 2023 systematic review of targeted interventions for concussion found that exercise prescription, cervical and vestibular rehabilitation, and psychological support all improved recovery when they were matched to the right patient [14]. That is what a trained concussion clinician does. They match the treatment to the symptom driver.

When Should You See a Concussion Clinician?

A reasonable rule of thumb: if you have a meaningful impact and any concussion symptoms, book a visit. Earlier is better. Specialty assessment in the first 48 hours has been linked to faster recovery, and early care seeking in adolescents has been linked to shorter overall recovery time [12][13]. The role of a concussion-trained clinician in that first visit is to confirm the diagnosis, screen for the things that should not be missed (cervical spine injury, vestibular disruption, vision problems, autonomic dysregulation), and give you a real plan instead of a “wait and see” letter.

The Complete Concussions Provider Network is a directory of clinicians who have been trained in this model and follow a standardized assessment and management process. You can find a Complete Concussions-certified clinic near you at completeconcussions.com.

Common Questions About the First 24 Hours After a Concussion

How long after hitting your head can concussion symptoms start?

Symptoms can begin immediately, or they can evolve over minutes to hours. Most symptoms appear within the first 24 to 48 hours. If a meaningful impact occurred, plan for at least one to two days of close observation, even if you feel fine at first [1].

Can you have a concussion and not know it?

Yes. You can have a concussion without losing consciousness, without vomiting, and without a dramatic hit. The majority of concussions happen without loss of consciousness, and many are missed because the symptoms look like fatigue, a regular headache, or feeling “off” [1]. If you took a real impact and feel different than normal, treat it as a possible concussion.

How do I know if I need a CT scan or MRI?

Most people with a concussion do not need imaging. CT scans look for bleeds and fractures. MRIs look for structural damage. Less than 1% of concussions show abnormalities on standard imaging [1]. Imaging is appropriate if there are red flags such as loss of consciousness lasting longer than a brief moment, repeated vomiting, severe headache, seizure, or any other red flag listed earlier in this article.

Is it safe to go to sleep after a concussion?

Yes, if there are no red flags and the person is acting normally. You do not need to wake the person every hour. Normal sleep helps the brain recover [14]. If you are unsure, have a clinician check first, or go to the emergency room.

When should I take my child to the doctor after a hit to the head?

Soon, and ideally within 24 to 48 hours, if any concussion symptoms are present. Children evaluated by a trained clinician early in their recovery tend to recover faster than those evaluated later [12][13]. If red flags are present, go to the emergency room first, then follow up with a concussion-trained clinician.

How long does a concussion last?

For most adults and athletes, symptoms improve within two to four weeks. About 15% to 30% of people have symptoms that last longer than a month, especially if they have pre-existing anxiety, prior concussions, or did not get early care [16][17][15]. Symptoms lasting beyond a few weeks are treatable and should be evaluated.

The Bottom Line

A concussion is a temporary disruption in how the brain works, not a sign that the brain is permanently damaged. The most important thing you can do in the first 24 hours is recognize that something happened, stay safe, watch for red flags, do less but not nothing, cut screen time without going to extremes, and get assessed early by a clinician who actually knows how to manage this injury. Doing those things well shortens recovery, lowers the risk of persistent symptoms, and replaces fear with a plan.

If you or someone you love has had a head impact and you are not sure what to do next, find a Complete Concussions-certified clinic near you at completeconcussions.com. You will get rapid access, an objective assessment, and a clear plan from day one.