Amitriptyline is a type of drug called an antidepressant. It's usually used to treat people with depression. Amitriptyline isn't a painkiller exactly, but it does seem to help with some kinds of pain.
If you have chronic tension headache and take amitriptyline regularly, you may get fewer headaches. And the headaches you do have should get better faster. 
Most of the studies we looked at found that amitriptyline helped.        These studies were of good quality ( randomised controlled trials). In one study, people taking amitriptyline had a headache three hours less a day, on average. 
Your doctor will start you on a low dose of amitriptyline, and increase it gradually if you need more. You'll probably take amitriptyline for about six months.  After this time, your doctor may want to see how you get on without the drug. You'll need to cut down your dose slowly over several weeks.  Your doctor will help you with this. If your headaches come back, you'll be able to start treatment again.
Like all drugs, amitriptyline can cause side effects. The most common ones are:  
Sleepiness (this happens in about 6 in 10 people)
A dry mouth (about 5 in 10 people get this)
Weight gain (about 2 in 10 people put on weight).
Research has found that taking antidepressants of all kinds can make some people more likely to think about suicide or try to harm themselves.  Young people under 18 are especially at risk. You are more likely to think about self-harm in the early stages of your treatment, or if your dose is changed.  If you're taking an antidepressant and are worried about any thoughts or feelings you have, see your doctor or go to a hospital straight away.
Antidepressants are medicines used to treat depression and sometimes other conditions. They work by changing the levels of chemicals in your brain called neurotransmitters. There are three main types of antidepressants, which work in different ways: selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants (TCAs).
Depression is a mental illness in which your mood is low and you feel sad most of the time. It can range from a mild illness through to a severe one in which you lose interest in life and may be suicidal.
randomised controlled trials
Randomised controlled trials are medical studies designed to test whether a treatment works. Patients are split into groups. One group is given the treatment being tested (for example, an antidepressant drug) while another group (called the comparison or control group) is given an alternative treatment. This could be a different type of drug or a dummy treatment (a placebo). Researchers then compare the effects of the different treatments.
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