Tension headache, also known as stress headache, or tension-type headache (TTH), is the most common type of primary headache. The pain can radiate from the lower back of the head, the neck, eyes or other muscle groups in the body typically affecting both sides of the head. Tension-type headaches account for nearly 90% of all headaches. Pain medications, such as paracetamol and ibuprofen, are effective for the treatment of tension headache. Tricyclic antidepressants appear to be useful for prevention. Evidence is poor for SSRIs, propranolol and muscle relaxants.As of 2016, tension headaches affect about 1.89 billion people and are more common in women than men (23% to 18% respectively). Signs and symptoms
According to the third edition of the International Classification of Headache Disorders, the attacks must meet the following criteria:

A duration of between 30 minutes and 7 days. At least two of the following four characteristics:
bilateral location
pressing or tightening (non-pulsating) quality
mild or moderate intensity
not aggravated by routine physical activity such as walking or climbing stairs
Both of the following:
no nausea or vomiting
no more than one of photophobia (sensitivity to bright light) or phonophobia (sensitivity to loud sounds)Tension-type headaches may be accompanied by tenderness of the scalp on manual pressure during an attack. Risk factors
Various precipitating factors may cause tension-type headaches in susceptible individuals:
Anxiety
Stress
Sleep problems
Young age
Poor health

Mechanism
Although the musculature of the head and neck and psychological factors such as stress may play a role in the overall pathophysiology of TTH, neither is currently believed to be the sole cause of the development of TTH.
Medications
People who have 15 or more headaches in a month may be treated with certain types of daily antidepressants which act to prevent continued tension headaches from occurring. In those who are predisposed to tension type headaches the first-line preventative treatment is amitriptyline, whereas mirtazapine and venlafaxine are second-line treatment options. Tricyclic antidepressants appear to be useful for prevention. Tricyclic antidepressants have been found to be more effective than SSRIs but have greater side effects. Evidence is poor for the use of SSRIs, propranolol, and muscle relaxants for prevention of tension headaches. Treatment
Treatment for a current tension headache is to drink water and confirm that there is no dehydration. If symptoms do not resolve within an hour for a person who has had water, then stress reduction might resolve the issue. Exercise
Evidence supports simple neck and shoulder exercises in managing ETTH and CTTH for headaches associated with neck pain. Exercises include stretching, strengthening and range of motion exercises. CTTH can also benefit from combined therapy from stress therapy, exercises and postural correction. Medications
Episodic
Over-the-counter drugs, like paracetamol, or NSAIDs (ibuprofen, aspirin, naproxen, ketoprofen), can be effective but tend to only be helpful as a treatment for a few times in a week at most. For those with gastrointestinal problems (ulcers and bleeding), acetaminophen is the better choice over aspirin, though both provide roughly equivalent pain relief.