Fentanyl — 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 Fentanyl?
Fentanyl is a potent synthetic opioid analgesic used for the management of severe chronic pain in opioid-tolerant patients, typically delivered via transdermal patch. This medication is commonly prescribed in New Zealand and is funded by Pharmac for severe chronic pain in opioid-tolerant patients.
What is Fentanyl Used For?
Fentanyl transdermal patches are used for severe, persistent pain in opioid-tolerant patients — such as those with cancer pain or severe chronic non-cancer pain who cannot be managed adequately with other opioids. Fentanyl injection is also used in anaesthesia and procedural sedation.
How Does Fentanyl Work?
Fentanyl binds to mu-opioid receptors in the central nervous system, producing powerful analgesia, sedation, and euphoria. It is approximately 100 times more potent than morphine. Transdermal delivery provides stable blood levels and avoids the peaks and troughs associated with oral dosing.
How to Take Fentanyl
The fentanyl patch is applied to a flat, non-irritated area of skin (upper arm, chest, back) and changed every 72 hours. Rotate application sites. Never cut, fold, or apply heat to the patch (heating increases absorption dangerously). Only for use in patients already stabilised on an equivalent opioid dose.
Common Side Effects of Fentanyl
- Drowsiness and sedation
- Constipation (opioid-induced — requires regular laxative use)
- Nausea and vomiting
- Dry mouth
- Itching at patch site or generalised
- Headache
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Respiratory depression (life-threatening — reduced breathing rate and depth)
- Opioid overdose (accidental exposure — including in children who find a patch)
- Severe hypotension
- Dependence and withdrawal
- Serotonin syndrome (when combined with serotonergic agents)
Drug Interactions
Fentanyl may interact with other medicines. Always inform your doctor and pharmacist of all medications, supplements, and herbal products you are taking. Key interactions include:
- CNS depressants (benzodiazepines, alcohol, other opioids — potentially fatal respiratory depression)
- Strong CYP3A4 inhibitors (ketoconazole, ritonavir — increase fentanyl levels dangerously)
- MAOIs (contraindicated)
- Serotonergic agents (serotonin syndrome risk)
New Zealand Prescribing Information
Fentanyl transdermal patches (25 mcg/h, 50 mcg/h, 75 mcg/h, 100 mcg/h — brands include Durogesic® and generics) are funded by Pharmac. Prescribing is restricted and requires specialist involvement in most cases. Used patches must be folded sticky side together and disposed of safely away from children and pets — contact your pharmacy for safe disposal options.
Frequently Asked Questions
Can I shower while wearing a fentanyl patch?
Yes, but avoid exposing the patch to very hot water, heating pads, or direct heat sources (including saunas and heat lamps). Heat increases the rate of fentanyl absorption through the skin, which can cause an accidental overdose.
What should I do if a patch falls off?
If a patch falls off before 72 hours, apply a new patch to a different skin site and contact your doctor or pharmacist for guidance on timing. Dispose of the used patch safely, folded sticky side together, out of reach of children and in a pharmacy disposal bin.
⚠️ 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 with any questions you may have regarding a medical condition or medication. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for the most current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: