TCAs are a class of drugs that's been used for decades to treat depression, anxiety, and certain kinds of pain.
Tricyclic antidepressants, also known as TCAs, were first approved by the Food and Drug Administration (FDA) to treat depression and obsessive-compulsive disorder (OCD).
These drugs work by increasing the concentrations of two mood-altering chemicals — the neurotransmitters norepinephrine and serotonin — in the brain.
While TCAs have been around for decades, scientists still aren't exactly sure how they cause these changes.
TCAs are thought to increase neurotransmitter levels by preventing nerve endings — called synapses — from drawing these chemicals back into their tissues, which is normally how the body reduces their concentrations.
Tricyclic antidepressants include:
- Amitriptyline
- Amoxapine
- Norpramin (desipramine)
- Pamelor (nortriptyline)
- Silenor (doxepin)
- Surmontil (trimipramine)
- Tofranil (imipramine)
- Vivactil (protriptyline)
Although first prescribed to treat depression, tricyclic antidepressants are now often prescribed off-label to treat nerve pain caused by diabetes or shingles, to help prevent migraines, to manage mood in panic disorder, and to relieve pain and other sensations felt in limbs that have been removed from the body (phantom limb pain).
Warnings and Precautions
The FDA requires that all tricyclic antidepressants carry a black-box warning on the label, notifying users that these drugs may make some people have suicidal thoughts or commit suicide.
Don't take a tricyclic antidepressant if you:
- Are allergic to TCAs or any of the drug's inactive ingredients
- Recently had a heart attack
Ask your doctor before taking TCAs if you:
- Are under age 25 or over age 65
- Have diabetes, heart problems, or a thyroid disorder
- Have any conditions affecting your urinary tract or an enlarged prostate
- Have glaucoma
- Have a liver disease
- Have a history of seizures
- Take medications to help manage your mood
Common Side Effects
Tricyclic antidepressants may cause a number of side effects, including:
- Dry mouth
- Blurred vision
- Sweating
- Dizziness or lightheadedness
- Drowsiness
- Restlessness
- Racing heartbeat
- Increased sweating
- Urinary retention
- Constipation
- Tremor
- Increased appetite
- Weight gain
- Low sex drive
- Difficulty achieving an erection, and other sexual difficulties
- Low blood pressure when rising to a stand
- Confusion in the elderly
Drug Interactions
TCAs interact with many different drugs, so ask your doctor or pharmacist about possible interactions before taking a tricyclic antidepressant.
Don't take TCAs if you're also taking:
- MAOIs such as Marplan (isocarboxazid) or Parnate (tranylcypromine)
- Zyvox (linezolid)
- Drugs for bowel preparation that contain phosphate, usch as OsmoPrep or Visicol
- Tagamet
- Alcohol
- St. John's wort
