Medically reviewed on May 22, 2018
What Is It?
A concussion is a short-term disturbance in brain function caused by a head injury. A concussion often causes:
Confusion, headache or dizziness
Loss of consciousness lasting less than 30 minutes or no loss of consciousness at all
Loss of memory (amnesia) lasting less than 24 hours
Most head injuries happen during motor vehicle accidents, falls, sports and assaults. Alcohol and drug use can be major contributing factors.
Usually there is direct trauma to the head (for example, the head hitting the ground or the windshield of a car). In the elderly, serious head injuries can result from even minor falls. Injuries also can occur from rapid acceleration or deceleration, as may happen in a whiplash injury. People who injure their heads often injure their necks, too.
Head imaging with MRI or CT scans of someone with a concussion rarely show obvious signs of brain injury.
Occasionally, minor head trauma can trigger a more serious problem such as bruising of the brain tissue (brain contusion) or bleeding within the head (subdural hematoma or subarachnoid hemorrhage). Bleeding and other complications of minor head injuries appear to be more common in the elderly and in people taking blood thinners such as warfarin (Coumadin).
A concussion can cause any or all of the following symptoms:
Nausea or vomiting
Dizziness or vertigo
Blurred or double vision
Changes in the ability to smell or taste
Irritability, anxiety or change in personality
Loss of memory (amnesia)
Confusion, difficulty concentrating or slowing of reaction time
Brief loss of consciousness
Symptoms most often appear immediately after the injury. However, in some cases, a person will feel fine at first and have the symptoms minutes to hours later.
Symptoms such as coma (unresponsiveness), seizures or paralysis or weakness of an arm or leg suggest a more serious form of head injury.
A doctor should check anyone who has a head injury, especially if the person lost consciousness or showed a change in thinking, such as confusion or memory loss. A doctor usually will want to know:
How your injury occurred
What symptoms developed after the injury
Whether you have had head injuries in the past (repeat injuries are more likely to cause serious damage)
Whether you have other medical problems
What medications you take
Whether you have been drinking alcohol or using drugs
Whether you have symptoms of other injuries (neck pain, shortness of breath, etc.)
The doctor will do a thorough physical and neurological exam. The doctor will check your blood pressure, pulse, vision, the way your eyes respond to light, reflexes and balance, and your ability to answer questions and remember things. If a doctor sees you immediately after a head injury, the examination may be repeated over several hours to make sure you are not getting worse.
If you have mild symptoms, are awake and alert, and have a normal examination, your doctor may just monitor you without doing any more tests. This monitoring can be done at home if you have had a very minor injury. If your symptoms are serious or your neurological exam is abnormal, you will likely need a CT scan of your brain to look for signs of a more serious head injury.
If you are sent home, have someone stay with you for the first 24 to 48 hours because symptoms can become worse quickly or you could lose consciousness if your injury is more serious than your doctor suspected.
Young people and athletes may recover from a head injury in minutes or hours. Some people experience lingering symptoms such as headache, dizziness, disrupted sleep, irritability and poor concentration for weeks or even months. In general, the more severe the concussion, the longer the recovery period. Doctors often use the term post-concussion syndrome for these lingering symptoms. The duration of a post-concussion syndrome varies. Most people recover completely within three months.
Repeated minor injuries over a short period greatly increase the risk of serious or permanent brain damage. Young people who play contact sports are at particular risk of these injuries. If you have had a head injury, talk to your doctor about when it is safe to return to your usual activities, including contact sports.
Accidents, including head injuries, are the leading cause of death in young people. Many of these accidents are related to drug and alcohol use. Many accidents can be prevented by avoiding dangerous activities or wearing safety equipment.
To help prevent head injuries:
If you drink alcohol, drink in moderation. Never drink or use drugs and drive.
Protect yourself from vehicle-related head trauma by wearing a seat belt, motorcycle helmet and bicycle helmet.
If you play sports, wear the right kind of protective headgear. If you suffer a blow to the head while playing, leave the game immediately and seek medical attention.
If your job involves working high above the ground, use approved safety equipment to prevent falls. Never work in a high place if you feel lightheaded or unsteady, if you have been drinking alcohol, or if you are taking medication that can make you dizzy or affect your balance.
Have your vision checked regularly. Poor vision can increase your risk of falls and other types of accidents. This is especially true if you are elderly or if you work in high places.
If you are elderly, clear your home or apartment of hazards such as throw rugs and extension cords, which can cause you to trip and fall. If you feel unsteady on your feet, consider using a cane or walker.
A person that has a concussion while playing sports must immediately stop. Return to play should not happen until the person has been evaluated by a health professional.
Most minor head injuries improve with rest and observation. Your doctor may choose to observe you in the hospital or may send you home under the care of a responsible adult. The doctor will give this person specific instructions about watching for danger signs.
There are no definitive guidelines regarding how long a person should rest. A reasonable approach is to avoid activities that are physically and mentally taxing for one to two days following the head injury. If symptoms recur when becoming more active again, slow down and notify your doctor.
No medication has been shown to speed recovery from a concussion. Headache and neck pains can be treated with over-the-counter pain relievers, such as acetaminophen (Tylenol and other brand names). If you have more severe pain, your doctor may give you a prescription pain reliever.
When To Call a Professional
Call for emergency help if you find someone unconscious at an accident scene. Seek immediate attention if someone with a head injury experiences any of the following symptoms:
Drowsiness or a decrease in alertness
Nausea or vomiting
Confusion or amnesia
Difficulty walking or poor coordination
Irrational or aggressive behavior
Numbness or paralysis in any part of the body
Even if a head injury appears minor, and the symptoms are mild, certain people are at high risk of serious complications. Call a doctor or go to an emergency room immediately if an injured person:
Takes medications to thin the blood
Has a bleeding disorder
Has a history of heavy alcohol or drug use
Most people with minor head injuries recover without any problems. Keep in mind, however, that some symptoms (headaches, dizziness, difficulty concentrating) may improve slowly over 6 to 12 weeks. Recovery will probably be slower in people whose injuries resulted in long periods of unconsciousness or amnesia. Recovery is also slower in the elderly, in those with previous head trauma, and in people with psychiatric or substance abuse problems.
A small percentage of people who suffer minor head injury may develop permanent disabilities or a condition called persistent post-concussive syndrome. This may include headaches, dizziness and difficulty concentrating. Consult your doctor if you still experience any symptoms three months after your head injury. Although there is no known cure for this condition, treatment is available for many of the symptoms.
Learn more about Concussion
Symptoms and treatments
National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
American Academy of Neurology (AAN)
1080 Montreal Ave.
St. Paul, MN 55116
Brain Injury Association of America
1608 Spring Hill Road
Vienna, VA 22182
Brain Trauma Foundation
708 Third Ave.
New York, NY 10017
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.