This information is for children and young people with depression. It tells you about tricyclic antidepressants. It is based on the best and most up-to-date research.
Do they work?
No. Tricyclic antidepressants don't seem to help with depression in children or teenagers. There's a risk of serious side effects if a child or teenager takes these drugs.
What are they?
Tricyclic antidepressants are a group of drugs that have been used to treat depression in adults for a long time. You might hear them called TCAs for short.
Most of them are not recommended for treating depression in young people.  But sometimes doctors might give them to a child or teenager who has both depression and another condition, such as attention deficit hyperactivity disorder ( ADHD for short).
The National Institute for Health and Clinical Excellence (NICE for short) is the government body that decides which treatments should be available on the NHS. It has published guidelines that say that people younger than age 18 should never be given tricyclic antidepressants for depression. 
For more, see NICE guidelines on depression in children and teenagers.
Examples of tricyclic antidepressants (and their brand names) are:
How can they help?
These drugs aren't likely to help. The research shows this type of antidepressant doesn't help children who are depressed. 
How do they work?
In adults, tricyclic antidepressants affect chemicals in the brain called neurotransmitters. These chemicals carry messages between brain cells. Tricyclic antidepressants make some neurotransmitters last longer, so they keep on carrying messages. These drugs affect several neurotransmitters, including serotonin, noradrenaline, and dopamine.
But in children, tricyclic antidepressants may not work the same way. This is because the neurotransmitter systems in children's brains aren't fully developed.  Also, the causes of depression in children may not be the same as in adults. 
Can they be harmful?
Yes. Studies show that tricyclic antidepressants can cause side effects.  Some common ones are:
Tricyclic antidepressants can be dangerous if you take too much. Some people have died after an overdose.  There have even been cases of young people dying suddenly while taking normal doses.  The risk of dying for children taking a tricyclic drug is less than 1 in 200,000.  But this risk isn't worth taking, because newer types of antidepressant don't cause this problem.
There's also a danger that children taking tricyclic antidepressants could swing from being depressed to having a very high mood. This is called mania.  Children could also go on to get several bouts of mania or depression in later life.