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Sideline Recognition: When to Remove an Athlete

By Dr. Neil J. Patel, MD, MBASports Neurology & Brain Injury MedicineLast reviewed: May 26, 20267 min read

The most important moment in concussion management is also the simplest: the decision to remove an athlete from play after a possible head impact. When in doubt, sit them out.

Observable signs that warrant immediate removal

• Loss of consciousness, even briefly
• Slow to get up after a head or body impact
• Disorientation, confusion, or inability to respond to questions appropriately
• Vacant or blank stare
• Balance problems, unsteadiness, or stumbling
• Forgetting events before or after the impact
• Slurred or incoherent speech
• Visible facial injury combined with any of the above

Symptoms reported by the athlete that warrant removal

• Headache or "pressure" in the head
• Nausea or vomiting
• Dizziness or balance problems
• Sensitivity to light or noise
• Feeling foggy, slowed, or "not right"
• Vision changes

If any of these are present after a possible head impact, the athlete must be removed from play and may not return that day, even if symptoms resolve quickly. This is the rule from the CDC HEADS UP program for coaches and from every major sports medicine organization.

Two practical realities make athlete-reported symptoms tricky. First, athletes minimize: the competitive instinct that makes someone good at sport also makes them say "I'm fine" reflexively. Asking specific questions — "Do you have a headache right now?" rather than "Are you okay?" — yields more honest answers. Second, symptoms evolve: an athlete genuinely free of symptoms two minutes after impact may develop a headache and fog twenty minutes later on the bench. Anyone removed for evaluation should be re-checked periodically, not assessed once and forgotten.

Tools that support — but do not replace — clinical judgment

The Sport Concussion Assessment Tool, 6th edition (SCAT6) is the standardized sideline assessment for athletes 13 and older. The Child SCAT6 covers ages 8-12. These tools structure the evaluation but do not diagnose concussion on their own — concussion remains a clinical diagnosis.

For settings without medical staff, the Concussion Recognition Tool 6 (CRT6) exists specifically for coaches, parents, and officials: it is a recognition and removal tool, not a diagnostic one, and its endpoint is simple — if anything on the list is present, the athlete comes off and stays off. Rapid sideline aids like the King-Devick test, which compares an athlete's timed number-naming against their own pre-season baseline, can add an objective data point where baseline testing programs exist. The shared principle across every tool: they lower the threshold for removal. No sideline tool exists to help someone talk an athlete back into a game.

One caution deserves emphasis: a normal sideline assessment minutes after impact does not rule out concussion. Symptoms commonly evolve over hours. An athlete who passes a sideline screen but took a significant impact should still be monitored, and any delayed symptom that evening triggers the same rule — no return until clinically evaluated.

Red flags: when the sideline becomes a 911 call

Most suspected concussions can be evaluated calmly. A small subset cannot. The following signs after a head or neck impact indicate a possible structural brain or spine injury and require emergency medical services immediately — not observation, not a car ride home:

• Neck pain or tenderness, or any concern for spine injury (do not move the athlete)
• Deteriorating consciousness or increasing drowsiness
• Repeated vomiting
• Severe or rapidly worsening headache
• Seizure or convulsion
• Double vision or unequal pupils
• Weakness, numbness, or tingling in the arms or legs
• Increasing confusion, agitation, or combativeness

These red flags are listed on the SCAT6 and in CDC guidance precisely so that the first decision on the sideline — emergency or not — is made before any cognitive testing begins.

After removal: the first 24 hours

Removing the athlete is the first half of the job. The second half is making sure the next steps actually happen. The athlete should not be left alone for the first several hours, and a responsible adult must know what to watch for overnight — worsening headache, repeated vomiting, unusual drowsiness or inability to wake, confusion, or seizure all mean an immediate emergency department visit. Waking a sleeping athlete every hour is no longer recommended; normal sleep helps recovery, provided someone checks that they are arousable at a reasonable interval early on.

The athlete should avoid alcohol, driving, and any further physical activity until evaluated. Equipment should be withheld — an athlete whose helmet is back in their hands has, in practice, been cleared by whoever handed it over. Within 24-72 hours the athlete should be evaluated by a clinician comfortable with concussion management, who will establish the symptom baseline, screen for red flags missed at the field, and set up the graduated return-to-play protocol and, for students, the return-to-learn plan.

Before the season: preparation makes the decision easy

Sideline decisions are hardest when they are improvised. Teams and leagues that handle concussion well decide everything in advance. That means a written emergency action plan for every venue — who calls 911, who meets the ambulance, where the nearest trauma center is. It means pre-season concussion education for coaches, athletes, and parents, which is required by youth sports concussion laws in all 50 states. It means knowing in advance which clinician will handle evaluations and clearance, rather than searching for one after an injury. And ideally it includes pre-season baseline testing, which gives the evaluating clinician each athlete's own healthy benchmark for comparison. When the plan exists, the in-game decision is reduced to the one judgment that matters: possible concussion, out of play.

The non-negotiable rule

A symptomatic athlete is not returning to play. There is no upside to forcing the decision, and the downside includes Second Impact Syndrome, prolonged recovery, and long-term risk. An athlete recovering from a suspected concussion should be evaluated by a clinician trained in concussion management before beginning a graduated return-to-play protocol.

"When in doubt, sit them out" endures as the universal teaching phrase because it resolves the hardest part of the sideline moment: uncertainty. You will rarely be certain a concussion occurred. You do not need to be. The threshold for removal is suspicion, not proof — and no game, at any level, is worth getting that backwards.