football players lined up across each-other
Avoiding Sports Injuries: Article 5 of 7

Sports Related Head Injuries: When Is It Safe to Return to Play?

Private: William Joseph Mullally, MD
Contributor William Joseph Mullally, MD

Sports participation is the second most common cause of head injury, behind motor vehicle accidents, among 15- to 24-year-olds. Traumatic brain injury (TBI) has become a major public health concern, and it is the responsibility of the medical community to protect athletes from suffering permanent brain damage. In the field of sports medicine, there remains confusion regarding the term “concussion.” Our main goal is to recognize when head trauma has resulted in a TBI.

In our opinion, the most sensitive indicator as to when a TBI has occurred is a sudden change in mental status. When there is any indication that an athlete has suffered a head injury, the athlete should immediately undergo a medical evaluation, and if there is a suspicion of a TBI or concussion, then the athlete should not return to play on the same day.

A more thorough medical evaluation should then be performed. As part of that evaluation, we recommend that all athletes undergo neurocognitive testing before participating in sports to establish a baseline level of brain function in terms of memory, attention, problem solving, and other measures. Comparison of pre- and post-injury neurocognitive tests can provide some of the information that’s needed to determine when it’s safe to resume play.

Levels of Sports-Related Head Injuries

We also have established a head injury grading system, with return-to-play guidelines, to assist sports medicine practitioners in identifying the severity of an injury and providing a uniform and logical timetable for a safe return to sports participation. We have defined five levels of head injury:

  • Grade 1 – Mild physical trauma to the head such as a bump, contusion, or laceration.
  • Grade 2 – Characterized by headaches that are often migraine-like in character, with associated symptoms.
  • Grade 3 – Mild traumatic brain injury (TBI), characterized by a sudden change in mental status or loss of consciousness for less than 1 minute, or amnesia for less than 30 minutes.
  • Grade 4 – TBI characterized by loss of consciousness for more than 1 minute and less than 5 minutes, or amnesia for more than 30 minutes, but less than 24 hours.
  • Grade 5 – Severe TBI, which can be life threatening. Athletes with Grade 5 injuries may suffer physical injuries to the brain, bleeding within the brain, and increased intracranial pressure. We include athletes who have lost consciousness for more than five minutes or experienced amnesia for more than 24 hours in the Grade 5 category.

Return-to-Play Guidelines

  • Grade 1 – Athletes can return to play as soon as the physical injury has healed.
  • Grade 2 – Athletes can return to play once they are asymptomatic and have completed a return-to-play protocol, which is a five-stage gradual increase in activity. We also recommend that athletes with Grade 2 injuries or higher undergo neurocognitive testing after injury. Once post-injury neurocognitive test results are favorable in comparison to the baseline and the symptoms have resolved, then the athlete can resume play.
  • Grade 3 – We recommend that athletes wait at least 10 days before they participate in any activity that can result in head trauma. They also must be asymptomatic and successfully complete the five-day return-to-play activity protocol. Returning to play after four such injuries should be considered only after receiving clearance from a neurologist or neurosurgeon.
  • Grade 4 – We recommend a 30-day break with a first injury, 90-day break with a second injury, and a 180-day break after a third injury. They may then return to play if they are asymptomatic and neurocognitive testing is favorable as compared to the baseline. We recommend that athletes not return to play after three Grade 4 injuries.
  • Grade 5 – Athletes may be able to return to play after six months if an MRI indicates that there was no evidence of structural damage inside the brain. This would include athletes who were unconscious for more than five minutes or had amnesia for more than one day and have a normal neurologic exam. They must be cleared by a neurologist or neurosurgeon. If an MRI shows evidence of an abnormality, such as brain contusion or increased intracranial pressure, or if the neurologic exam remains abnormal, then we recommend that those athletes never return to play.

With this grading system, we’ve tried to come up with guidelines that will enable athletes to resume participation in their sport, but also provide some degree of protection from long-term serious injury or Second Impact Syndrome (SIS). SIS can occur if athletes sustain a second traumatic brain injury while they are symptomatic from the first. This syndrome remains controversial, but case reports suggest that SIS can result in catastrophic injury or even death.

For more information about return to play guidelines, watch the video below that features Dr. Mullally.


Private: William Joseph Mullally, MD
William Joseph Mullally, MD

William Mullally, MD, is the Clinical Director of the Sports Neurology and Concussion Clinic at Brigham and Women’s Hospital and an Assistant Professor at Harvard Medical School.

Before you go,

Learn about innovative treatments for a wide range of conditions from headaches to brain tumors and stroke. Read more articles about brain conditions.