Some of the symptoms of a minor concussion include the following:

• Headaches—sometimes chronic—are one of the most common symptoms following a traumatic brain injury, with more than 30 percent of those suffering a traumatic brain injury having chronic, sometimes severe headaches for years after the initial injury. Chronic headaches can make it very difficult to continue regular daily activities, making it more difficult to concentrate and remember. When an area of the brain becomes hypersensitive following a traumatic brain injury, migraine headaches can occur. A migraine can cause sensitivity to light or sound, a dull, throbbing sensation, nausea or vomiting, and pain level generally rated as moderate to severe. Other types of headaches experienced following a TBI include tension headaches, cervicogenic headaches (usually following some level of injury to the muscles and soft tissues in the back of the head and neck), or rebound headaches that are actually caused by the medications used to treat other types of headaches. If a TBI-induced headache worsens over time, there is an increase in nausea and/or vomiting, arm or leg weakness occurs, problems speaking occurs, or there is increasing sleepiness with the headache, this is definitely cause for concern.
• Nausea is another common symptom of traumatic brain injury. Nausea can be short-term, associated with mild TBI (acute concussion), or could be situational or persistent even after recovery from the initial injury. While chronic nausea is fairly rare following a minor TBI, it is normal to be nauseous for days, or possibly even weeks, after the initial brain injury. There is typically inflammation and microstructural damage to the brain following a TBI that interferes with the communication channels in the brain, causing overload. These less efficient pathways between the brain cells cause many symptoms, including nausea. If those communication pathways don’t fully heal after the initial injury, nausea can persist.
• Dizziness and vertigo are commonly seen in those with mild traumatic brain injury, with up to 80 percent of those suffering a TBI reporting vertigo that lasts a week or more. Post-concussive dizziness can persist for weeks or months after the injury, with one out of five individuals suffering from a minor TBI reporting dizziness and vertigo for 2-5 years after the initial injury. Dizziness and vertigo following a TBI have been linked to work-related disability, psychological distress, and prolonged recovery duration, specifically dizziness that stems from a blast-induced injury among military members.  
• Confusion is very common in those with TBI, particularly those individuals who lose consciousness, even for a brief period of time. Doctors often term this “post-traumatic amnesia,” because it can include a loss of memory skills disorientation. Problems with attention span can be caused by the TBI-associated confusion, and the confusion can, in turn, lead to altered activity levels, delusions, hallucinations, and mood swings. In one study detailed by the Brain Injury Association of America, about 69 percent of individuals with TBI experienced some level of confusion, and about 71 percent of those largely recovered within 43 days, while the remainder suffered episodes of confusion (minor to severe) for months or years after.  
• Changes in mood and behavior are yet additional hallmarks of traumatic brain injury. A concussion can affect the brain long after it has healed from the initial injury; since the way we process and understand information can change as a result of the injury, it should come as no surprise that our emotions can also be altered. Social anxiety, or feelings of depression, irritability, anger, general anxiety, feelings of hopelessness, restlessness, decreased energy, difficulty sleeping, mood swings, or feelings of being overwhelmed can all result from a minor TBI. For many, it can seem as though they are a completely different person, but in truth, the individual’s personality is simply buried under the weight of TBI symptoms. Many mood and behavior changes can be managed when the overall TBI treatment is correct.