Tricyclic antidepressants (TCAs)

Types

There are many different types of tricyclic antidepressants.

Brand name Chemical name
Tryptanol Endep Amitriptyline
Tofranil Melipramine Imipramine
Prothiaden
Dothep
Dothiepin
Allegron Nortriptyline
Surmontil Trimipramine
Anafranil
Placil
Clopram
Clomipramine
Sinequan
Deptran
Doxepin

How tricyclic antidepressants work

Tricyclic antidepressants (TCAs) have been in use for more than 40 years. Despite this, we do not know exactly how they work. However, they do affect the chemicals noradrenaline (also known as norepinephrine) and serotonin. These chemicals are neurotransmitters and they are made by the cells in the brain. Neuorotransmitters are the means by which the brain cells connect and communicate with each other. The tricyclic antidepressants increase the amount of noradrenaline and serotonin in the brain. They also effect other neurotransmitters which cause some side effects (such as dry mouth). Over many years of study and use tricyclics have been shown to improve symptoms of depression and anxiety. They also reduce obsessions and compulsions in obsessive-compulsive disorders (OCD).

Side effects

Common side effects include:

  • Sleepiness (care needed with driving)
  • Dizziness on standing
  • Difficulty passing urine (especially in men)
  • Blurring of vision and problem with close vision (especially if you need glasses)
  • Tremor (slight shake of muscles of arms and hands)
  • Constipation
  • Confusion
  • Reduced sex drive and possible impotence

Effect on weight and sleep

  • Weight gain
  • Increase and stabilise sleep

Dangers

TCAs can cause:

  • Lowered blood pressure especially on standing. This may cause fainting.
  • Irregularities of heart beat
  • Glaucoma (raised pressure inside the eye causing pain, vision loss and possible blindness)
  • Urinary retention (blockage of urine)
  • Seizures in people subject to epilepsy (including people who may not have had fit before)
  • Confusion and restlessness – delirium (particularly in older people)

Cautions

If you are changing between medications be careful about any overlap of medications (see interactions below).

Overdosage

TCAs are very dangerous in overdose. Deaths have been very common with large overdoses. Overdose causes coma and can stop the heart. Go to hospital immediately in the case of an overdose.

Effect with alcohol

Tricyclic antidepressants increase the effect of alcohol and alcohol increases the drowsiness effect of the antidepressant.

Interactions with other drugs

Tricyclic antidepressants increase the effect of any drug that causes drowsiness or lowered blood pressure. They increase the effect of:

  • Sleeping tablets
  • Pain killers
  • Tranquillizers (like Valium, Serepax, Xanax etc)
  • Antipsychotic medications
  • Antihypertensive (Blood pressure controlling) medications

Tricyclic antidepressants can interact with the SSRI antidepressants and cause the Serotonin syndrome.

These interactions may require dosage adjustments of other medications taken.

When they must not be taken

TCAs must not be taken at the same time or soon after (within two weeks of) using Monoamine-oxidase inhibiting (MAOI) drugs (Parnate and Nardil)

Use in Pregnancy and Breast Feeding

Tricyclic antidepressants have not been shown to be harmful to the foetus in pregnancy. However, there have been few studies in humans. They should be used in pregnancy only if this is necessary for the health of the mother. Tricyclic antidepressants appear in breast milk in small quantities. Although this has not been shown harmful, the manufacturers recommend that the baby be weaned if treatment has to continue. Otherwise, if breast feeding is to continue, they recommend that tricyclics should be stopped. As the risk of harm is low, you should come to a decision about this with your own doctor.

Withdrawal effects

Antidepressants are not addictive. However, you may experience some withdrawal effects on stopping your antidepressant. Reactions vary between medications and between people. Sleep disturbance is common on stopping tricyclics. Some physical discomfort, restlessness and flu-like symptoms may occur if you suddenly stop tricyclics. These symptoms are reduced by stopping the medication gradually (over 2 weeks from higher doses). Don't stop taking your medication without seeing your doctor first.

Dosage and time of dose

The starting dose is usually very small and is gradually increased. Side effects are often intense when the medication starts but get less as the body grows used to it. This allows the dose to be increased to levels that work against depression. Some people break down the medications faster than others and need higher doses.

Nightime medication is most common. This is because most people find tricyclics cause sleepiness. This tends to keep them asleep through the night-time waking which is so common in depression. The time of dose does not change the effectiveness of the medication.

If a dose is missed, take it as soon as possible. If a night-time dose is missed, do not take it in the morning but take only the ordinary night-time dose the next night.

Name Common dose Most common time of dose
All tricyclic antidepressants  25mgm - 250mgm Evening

How long do you need to be on a medication?

You will need to take the antidepressant for at least 6 to 9 months after your symptoms disappear. Stopping your antidepressant too early increases your chances of suffering a recurrence of depression.

Are there problems with very long term use?

Tricyclics have been in use for more than 40 years. Some people have taken them for that length of time. There have been reports of abnormal muscle movement in older people after prolonged use. These are very rare and may be unrelated to the drug. No other problems have emerged beyond the side effects mentioned above.

Last reviewed and updated: 1 February 2006