TCAs – Tricyclic antidepressants

Tricyclic antidepressants (TCAs) have been available for more than 50 years. Tricyclic antidepressants are at least as effective as newer antidepressants such as selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs), but they usually cause more side effects, such as constipation, dry mouth and dizziness. This means they are not usually the first choice for treating depression, but they can be useful if other antidepressants don’t work for you, or if you have found that a TCA worked well for you in the past.

Tricyclic antidepressants include:

How do TCAs work?

Serotonin and noradrenaline are neurotransmitters — chemicals that relay signals between the cells in your brain. TCAs increase the amount of these two neurotransmitters in your brain, and this is how they are thought to improve the symptoms of depression.

How effective are TCAs?

About 50% of people treated with antidepressants find their depression symptoms are halved.
Although all antidepressants have shown similar efficacy when tested in groups of people in clinical trials, keep in mind that individuals can find one antidepressant works better for them than another. So if the first antidepressant you try doesn’t seem to be working for you after a few weeks, talk to your doctor about switching to another. A psychological therapy, such as cognitive behavioural therapy (CBT), could also be an option.

People who should take extra care with TCAs

Make sure you tell your doctor if you have, or have had in the past, any of the following (you might need to take extra precautions, or another medicine might be more suitable):

  • suicidal thoughts
  • a heart condition
  • prostate enlargement
  • glaucoma
  • hyperthyroidism
  • epilepsy
  • liver problems
  • bipolar disorder.

Get advice about the risks of taking antidepressants, directly from your doctor or from a specialist information line, if you are pregnant, breastfeeding or thinking about becoming pregnant. See Antidepressants, pregnancy and breastfeeding.

Older people should be particularly careful about taking a TCA because they increase the risk of falls, and older people may be more sensitive to other side effects like confusion, dizziness on standing, dry mouth and blurred vision. If a TCA is used, nortriptyline is often chosen because it is less likely to cause side effects. A lower starting dose may also be appropriate.

Side effects of TCAs

Side effects of tricyclic antidepressants as a group are listed below. For the side effects of individual medicines, see the consumer medicine information (CMI).

Not everyone experiences these side effects — the way an antidepressant affects you is quite an individual thing, so you might need to try more than one to find the one that suits you best. Some of the side effects will last only a week or two after you first start taking the medicine (e.g. insomnia, nausea, dizziness), while others (e.g. sexual side effects) tend to persist.

Remember that the risk of side effects with any medicine needs to be weighed against its benefit in treating your condition. Your doctor can help you weigh up the risks and benefits of taking particular medicine. See also Is this medicine right for me?

Frequency of side effects with TCAs

Common (1% of people or more)
Infrequent (between 0.1% and 1% of people)
Rare (fewer than 0.1% of people)

Sedation

Dry mouth

Blurred vision

Dry eyes

Constipation

Weight gain

Dizziness on standing

High heart rate

Problems urinating

Slow rate of digestion (can cause nausea, bloating)

Confusion (particularly in the elderly and in Parkinson's disease)

Sexual problems (loss of libido, difficulty reaching orgasm)

Shakiness or trembling

Dizziness

Sweating

Anxiety

Agitation

Insomnia

Changes in the rhythm or rate of the heart beat

Changes in the electrical signals in the heart

Nausea

High blood sugar level

Breast enlargement in males

Breast enlargement and milk production in females

Allergic skin reactions

Mania (overexcitement and uninhibited behaviour) 

An imbalance in numbers of different blood cell types

Hepatitis

Paralysis of the intestines

Seizures (fits)

Syndrome of inappropriate antidiuretic hormone secretion  (SIADH). This causes your body to retain more water and lowers blood sodium, which can have serious consequences (seizures, coma or death)

TCAs and alcohol

Tricyclic antidepressants can make the effects of alcohol stronger. Talk to your doctor about safe limits for you.

TCAs and driving or operating machinery

Tricyclic antidepressants can make you drowsy, and this can persist the next day — if you are affected, do not drive or operate machinery.

For more information

References
  • Rossi S, ed. eAMH [online]. Adelaide: Australian Medicines Handbook, 2012. www.amh.net.au. (Accessed 9 February 2012).
  • National Collaborating Centre for Mental Health. Depression: the NICE guideline on the treatment and management of depression in adults (updated edition). London: National Institute for Health and Clinical Excellence, 2010. www.nice.org.uk/nicemedia/live/12329/45896/45896.pdf (accessed 9 February 2012).