Doctors and other health professionals who treat adults with concussion symptoms that last for months now have an updated set of guidelines to consult.

The most frequent symptoms of concussion are headache, dizziness, nausea and imbalance. Most resolve relatively quickly but about 10 to 15 per cent of people with a concussion don't improve.

The Ontario Neurotrauma Foundation published its "Guidelines for Concussion/Mild Traumatic Brain Injury and Persistent Symptoms" on Tuesday to help doctors treat patients whose physical or mood symptoms like irritability persist for weeks to months.

While concussions are commonly thought of as a sports injury, many of the brain injuries come from falls, car collisions, assaults or recreational activities. In all concussions, resting the brain is the first step. The guidelines offer direction for the minority of patients for whom rest alone isn't enough.

Dr. Shawn Marshall is the lead author of the guidelines and a doctor at The Ottawa Hospital Rehabilitation Centre."We've given more emphasis and direction on how to manage patients with regard to return to work issues and return to school," he said in an interview.

For adults, return to school may include university students, which he called an important population because they tend to be more physically active and prone to concussion.

The guidelines include a symptom-based approach. For headaches for example, the guide covers assessment, what to avoid, how to mitigate the effects of headache, and medications.

Leah Braithwaite of Ottawa was one of the minority of patients with concussion whose symptoms persisted after she was knocked down by a beginner skier in February 2011.

"My physician diagnosed my concussion, but didn't have a program for managing my lingering and debilitating symptoms," she said in a release.

Braithwaite used sick leave and spent time in a darkened room. When Braithwaite returned to her job, extended time working brought back the physical symptoms. She couldn't bear the sound of dishes being unloaded from the washer.

Now, 2½ years later, she is managing some symptoms such as fatigue and headaches but has returned to her previous level of activity after easing back into full-time work nine months after sustaining the concussion.

The foundation expects to publish guidelines on managing persistent concussion symptoms in children and youth next year.