So, you’ve hit your head.  Or maybe you haven’t.  Maybe your neck has been whipped back and forth, like in a car accident, or perhaps you’ve had a hard fall and feel shaken up.  If you find yourself with a headache, feeling dizzy, nauseous, or just feeling like something is off, you might be asking yourself: “do I have a concussion?”  It’s an important question to consider, and in this post we’ll discuss common signs and symptoms of a concussion and how to know when it’s time to get evaluated by a healthcare professional with experience in concussion management.

What is a Concussion?

A concussion, also referred to as a mild traumatic brain injury (mTBI), is a type of brain injury that occurs when the brain is forcefully shaken. This can happen due to a direct blow to the head, whiplash or sudden movements that cause the brain to move back and forth within the skull.  You do not actually have to hit your head to get a concussion. The injury occurs due to the stretching of the brain tissue when it accelerates inside of the skull and then rapidly decelerates. This injury to the brain tissue can cause chemical changes in the brain and in some instances damage to brain cells, leading to a variety of symptoms.  A concussion is a functional injury of the brain rather than a structural one, meaning that no abnormalities will be seen on diagnostic imaging like a CT scan or MRI.  With that said, there may be some instances where it is appropriate to have such imaging performed to rule out a more serious injury.  We’ll revisit this later.

Common Signs and Symptoms

The signs and symptoms of a concussion may vary from person to person, as well as the severity and duration. It’s important to note that not all symptoms will appear immediately after the injury, but usually within 48 hours.

Below are some common ones you should be aware of:

  • Headache or pressure in the head.
  • Dizziness or balance problems.
  • Nausea or vomiting.
  • Double or blurry vision.
  • Feeling “foggy” or dazed.
  • Fatigue or low energy.
  • Difficulty concentrating or remembering things.
  • Feeling tired, fatigued, or sluggish.
  • Sensitivity to light or noise.
  • Ringing in the ears.
  • Personality changes such as feeling more emotional or irritable.

Signs It’s More Serious!

Now that you know what some of the common signs and symptoms of a concussion are, let’s look at some signs that could indicate a more serious brain injury.  These signs warrant immediate medical attention, and should never be ignored.

  • Loss of consciousness (doesn’t predict concussion severity, but could indicate more serious injury).
  • Severe or worsening headache.
  • Feeling extremely drowsy or having difficulty staying awake.
  • A decreasing level of consciousness more than 2 hours after the injury.  This may present as having difficulty recognizing people or places.
  • Weakness, numbness, or tingling in the arms or legs.
  • Slurred speech or significant unsteadiness on your feet.
  • Vomiting.
  • Clear fluid leaking from the nose or ears (this is cerebrospinal fluid).
  • Bruising behind the ears and two black eyes (can indicate a basal skull fracture).
  • Abnormal sense of taste.
  • Difficulty speaking or swallowing. 
  • Difficulty understanding speech.
  • Tremors.
  • Inability to remember what took place more than 30 minutes before the injury.

If you experience any of the above signs and symptoms after an injury, seek immediate medical attention.  If you’re with someone who shows any of these signs after an injury, help them get to the nearest emergency department.


Loss of Consciousness

Any impact that causes you to lose consciousness has almost certainly resulted in a concussion, especially if the loss of consciousness is accompanied by any of the above symptoms.  It can also be a sign of a more serious brain injury. However, 90% of concussions do not involve a loss of consciousness.

If you experience any combination of these symptoms after your injury, it is best to assume that you have a concussion until told otherwise by a healthcare provider with experience in concussion management.

How Long Do Symptoms Last?

As mentioned earlier, the duration of concussion symptoms can vary from person to person.  Statistically speaking, about two-thirds of individuals will see their symptoms resolve in 7-10 days [1] though the physiological recovery of the brain takes anywhere from 22-30 days [2].  We’ll talk more about the significance of this important difference in the time between symptomatic recovery and physiological recovery later on.  The other one-third of people are not as fortunate, and will see their symptoms persist for several weeks, months or even years if they do not receive the appropriate treatment.  Individuals with prolonged symptoms beyond the typical 7-10 day timeframe are generally considered to have post-concussion syndrome. 

Some concussion symptoms that appear initially after an injury may disappear and then return after exposure to a certain situation or after performing a specific activity.  This is generally an indication that things have improved but haven’t resolved completely.  However, there may also be situations where few or no initial symptoms are present, but are experienced later with activities like physical exertion or working on the computer. 

It is particularly important to seek medical attention from an experienced provider if your symptoms last more than the typical 7-10 days, as the single best predictor of recovery time is how quickly a person winds up in the care of a practitioner with experience in diagnosing and managing concussions [3].

Anything Triggering Your Symptoms?

Woman experiencing headache as her post-concussion symptom

Sometimes after a head injury or other impact, no obvious symptoms are present right away, and this was in fact my own experience when I sustained my first (and only) concussion about a year and a half ago.  In this particular instance, I merely felt a bit “spaced out” or dazed for an hour and then felt nothing out of the ordinary.  It wasn’t until I started performing certain activities the following day that I began to suspect that I had a concussion. 


Visually Demanding Activity

One common activity that can trigger symptoms includes visually intensive work like reading or working on the computer.  In my case, I noticed I was getting a headache after about 20 minutes on my computer the day after my suspected concussion.  The visual system accounts for a large amount of the brain’s processing power in a typical day, and activities that are visually demanding can provoke symptoms while the brain is still healing.


Visual Motion and Spatial Relationships

Activities with a lot of visual motion or that challenge your brain’s sense of spatial awareness, like driving , can also provoke symptoms.  The morning after my injury I noticed that I was feeling nauseous when driving through roundabouts (or traffic circles, as they’re known in some parts of the world).  Such an activity requires your visual and vestibular systems to work hand-in-hand to help your brain understand how you’re navigating your environment, and the relative movement of the vehicle while you yourself remain relatively still inside of it.  Following a concussion, your brain and these corresponding systems may have difficulty with this processing, resulting in symptoms.  In some instances, ongoing dysfunction of the visual and vestibular systems can be the cause of prolonged symptoms in the one-third of patients who don’t feel better within the typical recovery timeline.


Physical Exertion

Another very common trigger for symptoms following a concussion is physical exertion.  Initially after a concussion, our nervous system’s ability to regulate blood flow to our brain is impaired.  In some patients, this may go on for longer than the initial 7-10 day period, and in fact one of the drivers of prolonged symptoms can be the impaired ability of our autonomic nervous system to regulate cerebral blood flow.  In my own experience, all of my symptoms, including the ones provoked by driving and being on the computer, were gone after about a week.  However, when I tried to go for a run a couple days after that, I found myself with a headache about 10 minutes in.

It’s important to note that while physical exertion can trigger symptoms after a concussion, you don’t want to avoid it altogether.  In fact, sub-symptom aerobic exercise (exercise just below the level that brings on symptoms) is the best supported treatment for a concussion injury according to the available scientific literature [4].   A healthcare provider with experience in managing concussions can help you figure out what intensity you should be exercising at after your concussion, (using the Buffalo Concussion Treadmill Test) and how to slowly increase that as your symptoms improve.


Busy, Stimulating Environments

Another scenario that could provoke symptoms after a concussion include being in busy, stimulating environments like a classroom or a grocery store, or those with brighter lights and loud, continuous noise, like a concert.  People with mild traumatic brain injuries may also have difficulty following a conversation if there are other things going on around them, or will have symptoms worsen while trying to concentrate.

If you’re noticing that any of the scenarios or activities described above are triggering some of the signs and symptoms discussed earlier, it’s time to get checked by an experienced provider.

The Vulnerable Window and Second Impact Syndrome

We briefly mentioned earlier that there is often a difference in time between the resolution of symptoms and the physiological healing of the brain.  For the two-thirds of people whose symptoms resolve in 7-10 days, this represents a window of vulnerability where the individual feels fine or “back to normal”, but their brain is still healing for at least another couple of weeks.  It is extremely important to recognize this, because an individual who sustains a second concussion during this period may suffer more significant consequences.  When an individual suffers a subsequent concussion while still in the period of physiologic recovery (22-45 days post-injury) from a previous concussion, it is generally referred to as second impact syndrome (SIS).  In rare cases, this can actually be fatal [5].

For a typical concussion, the brain’s energy levels drop temporarily, but there shouldn’t be any permanent damage to brain cells.  However, those who suffer a second concussion while still recovering from the first, are at risk of brain cell death that could result in some permanent deficits.  Even in the absence of cell death and permanent impairment, a second concussion during the vulnerable window often leads to a much longer recovery process [5].


A Fatal Mistake

In some cases, second impact syndrome can in fact lead to death due to poor auto-regulation of cerebral blood flow, which results in significantly increased intracranial pressure [5].  This fatal brain swelling, while exceptionally rare, is reason enough to always proceed with an abundance of caution following a concussion injury,  making every effort not to expose a concussed person to a situation where they are at risk of another impact.  This is especially vital in the context of those who may not know enough to make such a decision for themselves, like a young athlete.  For coaches and parents, remember: when in doubt, sit them out!

Where There’s Concussion, There’s Whiplash

Whiplash is a symptom of a concussion

There still exists a common misconception that you have to hit your head to get a concussion, and unfortunately there are still many medical providers out there who still subscribe to this now-proven-false belief.  A direct blow to the head is not required to cause the brain to rapidly accelerate and decelerate within the skull, which is the mechanism behind concussion injuries.  A whiplash injury, which occurs when the neck moves suddenly and forcefully in one direction and then rebounds back just as quickly, can produce the type of movement of the brain within the skull that is needed to cause a concussion.  It also causes a sprain/strain injury to the neck. 


It’s All About the G’s

The amount of force (measured in gravitational force, or G’s) required to cause a concussion injury is approximately 70-120 G’s [6].  The amount of force required to cause a whiplash injury is approximately 4.5 G’s.  As such, nearly every concussion injury comes with some accompanying whiplash injury, though every whiplash injury does not come with a concussion.  It’s also crucial to note that untreated whiplash and neck dysfunction is another common cause of prolonged symptoms after a concussion.  Whiplash symptoms commonly overlap with concussion symptoms, and it’s important to ensure that your neck is adequately assessed and treated if you suspect you’ve suffered a concussion. 

I Think I Have One, What Should I Do?

If you’ve taken note of your symptoms, you don’t have any signs of a more severe head injury, and you suspect that you do have a concussion, you’ll probably find yourself wondering “what do I do now?”  If possible, you should seek an assessment with an appropriate healthcare provider at your earliest opportunity.  As mentioned earlier in this article, the best predictor of time to recovery is how quickly you wind up in the care of a provider with experience in concussion management [3]. 

In the interim, it is generally advised that you rest for about 24-48 hours.  After this time, rest actually does more harm than good in the overwhelming majority of cases because it can lead to deconditioning of the brain.  You should slowly start to re-engage in all of your regular day-to-day activities, provided they do not involve any notable risk of additional impact or injury, and provided they do not make your symptoms significantly worse.  Light aerobic exercise such as walking is encouraged, and an experienced treatment provider can help guide your progression to more strenuous activity.

Finding an Appropriate Provider

Doctor explaining a concussion to a a patient during a concussion care session

Making sure that you end up in the care of an experienced provider is paramount to ensuring that you receive the right treatment to get you on the road to recovery.  Look for a provider that has taken additional courses beyond their regular education and training that are specific to diagnosing and treating concussion injuries.  Don’t be afraid to ask them what their experience is like treating concussion patients, and what kind of training they’ve received.  If they tell you to treat your concussion by sitting in a dark room and resting until you feel better, find a new provider ASAP, as this is an automatic indication that they do not possess the most up-to-date knowledge on concussion rehabilitation.  Use some of the information you’ve gained by reading this article and others (Our Complete Concussions blog is full of other articles containing useful information about concussion injuries and how to treat them) to ask pointed questions about your injury and recovery process, and don’t be afraid to seek a second opinion if you have doubts about your treatment plan.

To find a Complete Concussions trained clinician in your area click here.

  1. Ewing-Cobbs L, Cox CS Jr, Clark AE, Holubkov R, Keenan HT. Persistent Postconcussion Symptoms After Injury. Pediatrics. 2018;142(5):e20180939. 
  2.  Vagnozzi R, Signoretti S, Cristofori L, et al. Assessment of metabolic brain damage and recovery following mild traumatic brain injury: a multicentre, proton magnetic resonance spectroscopic study in concussed patients [published correction appears in Brain. 2013 Nov;136(Pt 11):i1. Marziale, Simone [corrected to Marziali, Simone]]. Brain. 2010;133(11):3232-3242.
  3. Taylor Pratile, Cameron Marshall & Carol DeMatteo (2022) Examining how time from sport-related concussion to initial assessment predicts return-to-play clearance, The Physician and Sportsmedicine, 50:2, 132-140
  4. Leddy JJ, Haider MN, Ellis MJ, et al. Early Subthreshold Aerobic Exercise for Sport-Related Concussion: A Randomized Clinical Trial. JAMA Pediatr. 2019;173(4):319-325. 
  5. May T, Foris LA, Donnally III CJ. Second Impact Syndrome. [Updated 2023 Jul 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from:
  6. Broglio SP, Eckner JT, Kutcher JS. Field-based measures of head impacts in high school football athletes. Curr Opin Pediatr. 2012;24(6):702-708.