Post-concussion syndrome (PCS) is the term used to describe a collection of symptoms that can last for several weeks or months after the concussion.

The exact cause of PCS is not known. One theory is that PCS is the result of a chemical imbalance in the brain triggered by the initial injury that caused the concussion. Another theory suggests PCS may be caused by damage to nerve cells in the brain.

Symptoms of PCS

The symptoms of PCS fall into three main categories:

• physical
• psychological
• cognitive (affecting a person's thinking ability)

Physical symptoms of PCS can include:

• headaches – often described as similar to migraines in that they cause a throbbing pain on one side or the front of the head
• dizziness
• feeling sick (nausea)
• sensitivity to bright lights
• sensitivity to loud noises
• ringing in the ears – the medical term for this is tinnitus
• double or blurred vision
• fatigue
• lost, changed or reduced sense of smell and taste

Psychological symptoms of PCS can include:

• depression
• anxiety 
• irritability
• lack of energy and interest in the world around you
• having problems sleeping
• changes in appetite
• sudden and inappropriate outbursts of emotion, such as having fits of laughter or crying for no apparent reason

Cognitive symptoms of PCS include:

• decreased concentration
• forgetfulness
• difficulty remembering things or learning new information
• difficulties with reasoning (working out problems)

Treating PCS

There is no specific treatment for the symptoms of PCS, though many medications used to treat migraines have also proved effective in treating the headaches caused by PCS.

Antidepressants and talking treatments such as psychotherapy may help control the psychological symptoms, such as depression and anxiety.

Most cases of PCS will resolve within three to six months, and only 1 in 10 people will still have symptoms after a year.