Amitriptyline — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Amitriptyline?
Amitriptyline is a tricyclic antidepressant (TCA) widely used at low doses for neuropathic pain, migraine prevention, and insomnia. This medication is funded by Pharmac for depression, neuropathic pain, and migraine prevention.
What is Amitriptyline Used For?
At low doses (10–50 mg): used for neuropathic pain, migraine and tension headache prevention, fibromyalgia, insomnia, and IBS. At higher doses (75–150 mg): used for major depressive disorder.
How Does Amitriptyline Work?
Inhibits noradrenaline and serotonin reuptake (enhancing descending pain inhibition), blocks sodium channels, histamine H1 receptors (sedation), and muscarinic receptors. These multiple actions explain its use across diverse conditions.
How to Take Amitriptyline
For pain/sleep/migraine prevention: 10–25 mg at bedtime, increase slowly by 10 mg every 1–2 weeks as needed. For depression: 75–150 mg/day (as single bedtime dose or divided). Full antidepressant effect takes 2–4 weeks.
Common Side Effects of Amitriptyline
- Drowsiness (take at bedtime)
- Dry mouth
- Constipation
- Blurred vision
- Urinary retention
- Weight gain
- Dizziness on standing
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Cardiac arrhythmias and QT prolongation (significant — dangerous in overdose)
- Anticholinergic toxidrome (urinary retention, acute confusion, glaucoma)
- Seizures (rarely)
- Severe orthostatic hypotension
- Suicidal ideation (monitor in younger patients at initiation)
Drug Interactions
Amitriptyline may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- MAOIs (contraindicated — life-threatening serotonin syndrome)
- QT-prolonging medicines (additive cardiac risk)
- Other serotonergic medicines
- Anticholinergic medicines (additive effects)
- CNS depressants and alcohol
- CYP2D6 inhibitors (fluoxetine, paroxetine — increase amitriptyline levels significantly)
New Zealand Prescribing Information
Amitriptyline (10 mg, 25 mg tablets) is funded by Pharmac. At low doses (10–25 mg at night) it is widely used by GPs for pain and sleep with acceptable tolerability. At antidepressant doses it is less commonly used than SSRIs due to side effects and overdose risk.
Frequently Asked Questions
Can I take amitriptyline during the day?
Amitriptyline causes significant sedation — most patients take it at bedtime. Daytime dosing is generally not recommended unless under specific medical guidance.
Is amitriptyline addictive?
Not in the traditional sense. However, stopping abruptly can cause a discontinuation syndrome (nausea, agitation, flu-like symptoms). Always taper gradually under medical supervision.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: