Concussion symptoms can be subtle and don’t always show up right away. Some appear within minutes, while others take hours or even days to develop. That means checking for a concussion isn’t a one-time assessment. It’s an ongoing process of watching for physical, cognitive, and behavioral changes after a head injury.
What to Look for Right Away
Certain signs are visible immediately after an impact, even before the injured person can tell you how they feel. Watch for someone lying motionless after a hit, falling without bracing themselves, appearing disoriented or confused, or having a blank, vacant look on their face. Difficulty walking or standing steadily, a seizure at the time of impact, or any loss of consciousness are also immediate red flags.
If the person is alert and talking, ask a few simple orientation questions: What day is it? Where are you? What happened just before the injury? Confusion or inability to answer correctly suggests a concussion. In sports settings, clinicians use specific memory questions about the game, such as which team they’re playing or what the score is, to quickly gauge cognitive function.
Physical Symptoms
Headache is the most common concussion symptom, but it’s far from the only one. The CDC groups physical symptoms into a clear pattern: headache, dizziness or balance problems, nausea or vomiting (especially early on), sensitivity to light or noise, blurred or double vision, and fatigue or low energy. A person doesn’t need all of these to have a concussion. Even one or two, following a head impact, should be taken seriously.
Nausea and vomiting tend to appear soon after the injury and often resolve within the first day. Sensitivity to light and noise can persist longer and is often one of the more disruptive symptoms in daily life.
Cognitive and Emotional Changes
Concussions affect thinking and mood, not just the body. Watch for trouble concentrating, feeling mentally “foggy” or slowed down, difficulty remembering things (especially the events surrounding the injury), and trouble thinking clearly. The person may seem like they’re processing conversations a beat too slowly or struggling to follow along.
Emotional changes are easy to overlook but just as telling. Increased irritability, feeling more emotional than usual, sadness, and anxiety or nervousness all show up on the CDC’s concussion symptom list. These can be mistaken for a bad mood or stress, especially in teenagers, so it’s worth connecting the dots back to a recent head injury.
Sleep disruption rounds out the picture. Sleeping more than usual, sleeping less, or having trouble falling asleep are all associated with concussion. If someone who normally sleeps well suddenly can’t, or someone who’s usually energetic wants to nap constantly, that’s a meaningful signal.
A Simple Balance Check You Can Do at Home
Balance testing is one of the most practical ways to screen for a concussion outside a clinic. The Balance Error Scoring System, or BESS, is used by athletic trainers and can be adapted at home in a simplified form.
Have the person close their eyes and stand in three positions, each for 20 seconds: feet together with hands on hips, standing on one leg (the non-dominant leg) with hands on hips, and a tandem stance with one foot directly in front of the other, heel to toe. You’re watching for errors: opening their eyes, lifting their hands off their hips, stepping or stumbling to regain balance, swaying significantly, or lifting a heel or forefoot. Multiple errors across these stances suggest impaired balance, which is a hallmark of concussion.
This isn’t a definitive test on its own, but it’s a useful data point, especially when combined with other symptoms. If someone can’t hold a single-leg stance for more than a few seconds with eyes closed after a head impact, that’s worth noting.
Eye Movements and Coordination
Your eyes reveal a lot about brain function after a hit. Clinicians use a screening called VOMS (Vestibular/Ocular Motor Screening) that tests smooth eye tracking, rapid eye movements side to side and up and down, the ability to focus on a close object, and sensitivity to visual motion. You can approximate some of these at home.
Hold a finger about arm’s length away and slowly move it side to side, then up and down, asking the person to follow it with their eyes without moving their head. Jerky tracking, difficulty keeping focus, or the person reporting that it makes their headache, dizziness, or nausea worse all point toward concussion. You can also try a simple finger-to-nose test: have them touch their nose, then touch your fingertip, alternating back and forth. Clumsiness or missing the target suggests impaired coordination.
Monitoring Over the First 24 to 48 Hours
Because symptoms can appear hours or even days after the injury, close observation in the first 24 to 48 hours is essential. Contrary to the old belief that you need to wake someone up every hour, it’s generally safe to let a person with a concussion sleep. Rest is actually a crucial part of early recovery. The key is that someone nearby knows the warning signs of a more serious brain injury and checks in periodically.
Call emergency services immediately if any of the following develop:
- Worsening headache that doesn’t go away
- Repeated vomiting
- Seizures or convulsions
- Slurred speech or unusual behavior
- One pupil larger than the other
- Inability to recognize people or places, increasing confusion, restlessness, or agitation
- Weakness, numbness, or loss of coordination
- Loss of consciousness or inability to be woken up
These signs can indicate a blood clot forming between the skull and brain, which is rare but dangerous. A person who initially seemed fine after a head injury can deteriorate, which is why ongoing monitoring matters more than a single check.
Checking Children and Toddlers
Young children, especially those who can’t clearly describe how they feel, require a different approach. You’re relying almost entirely on observable behavior. Watch for excessive crying that can’t be consoled, changes in eating or nursing patterns, loss of interest in favorite toys or activities, unsteady walking, and increased irritability or crankiness beyond what’s normal for the child.
The same physical symptoms apply (vomiting, drowsiness, balance problems), but toddlers may express headache or dizziness through fussiness rather than words. Any change in behavior or personality after a head bump in a young child warrants a medical evaluation within one to two days, even if no emergency symptoms are present.
What a Clinical Evaluation Looks Like
No single test definitively diagnoses a concussion. It’s a clinical judgment made by a healthcare provider based on the full picture: the mechanism of injury, symptoms, cognitive testing, balance assessment, and eye movement screening. The current standard clinical tool, the SCAT6 (Sport Concussion Assessment Tool, 6th edition), takes at least 10 to 15 minutes and includes a 22-item symptom checklist, word recall tests, digit and month reversal tasks to test concentration, and the balance and coordination checks described above.
Importantly, a normal score on these assessments doesn’t rule out a concussion. Some people test within normal limits and still have one. CT scans and MRIs are typically used only when a more serious injury like a skull fracture or brain bleed is suspected. A standard concussion won’t show up on imaging.
If you or someone you’re with has taken a hit to the head and is showing even a few of the symptoms outlined here, a medical evaluation within one to two days is recommended, even when the situation doesn’t feel like an emergency. Early identification leads to better management and a faster return to normal activity.