A concussion is an injury to the brain resulting from a hit to the head or a body hit which causes a sudden acceleration or deceleration of the head. It does not cause brain bleeding but does change the brain's ability to function normally. The symptoms can be subtle and may be missed or downplayed.
Symptoms generally occur immediately after the injury but may not be noticed initially. They can last for hours, days, or sometimes even weeks to months in more significant injuries. Symptoms may include: Significant headache, mild headache that persists, confusion, nausea and/or vomiting, blurry vision, memory problems, balance problems, difficulty focusing, fatigue, sensitivity to light or noise, irritability, feeling sad or anxious, sleep problems, or loss of consciousness.
When a concussion is suspected in an athlete, that athlete should not return to the game or practice that same day, and anyone with a suspected concussion should be evaluated by a medical professional for diagnosis. The mainstay of concussion treatment is mental and physical rest to allow the brain to heal. Initially, this means avoiding all vigorous physical activity and limiting cognitive activities (i.e. limited work/schoolwork, videogames, texting, etc.) while symptoms persist.
There is some evidence showing that if symptoms last for several weeks there may be some benefit to low-level physical activity under the guidance of a medical professional. Additionally, certain medications may be beneficial to treat concussion symptoms which persist beyond several weeks. Long-term symptoms are called "post-concussion syndrome".
Once symptoms have resolved completely, returning to activity should be done gradually in a step-wise progression to avoid returning too quickly and causing symptoms to recur.