Morphine — 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 Morphine?
Morphine is a potent opioid analgesic derived from the opium poppy, used for the management of moderate to severe pain. This medication is commonly prescribed in New Zealand and is funded by Pharmac for moderate to severe pain and palliative care.
What is Morphine Used For?
Morphine is used for moderate to severe acute pain (e.g., post-surgical, trauma, myocardial infarction), cancer pain, palliative care, and breathlessness in end-of-life care.
How Does Morphine Work?
Morphine binds to mu, kappa, and delta opioid receptors in the central and peripheral nervous systems, inhibiting pain signal transmission, altering the emotional response to pain, and producing analgesia, sedation, and euphoria.
How to Take Morphine
Available in immediate-release and modified-release oral forms, as well as injection for hospital/palliative use. Immediate-release formulations are taken every 4 hours. Modified-release (e.g., Kapanol®, MS Contin®) is taken every 12 hours. Always take with or after food to reduce nausea. Never crush or chew modified-release tablets.
Common Side Effects of Morphine
- Constipation (nearly universal — start a laxative proactively)
- Nausea and vomiting
- Sedation and drowsiness
- Dry mouth
- Urinary retention
- Itching
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Respiratory depression (life-threatening overdose — seek emergency care)
- Loss of consciousness
- Severe hypotension
- Opioid-induced hyperalgesia (paradoxical increased pain with high doses)
- Dependence, tolerance, and withdrawal
Drug Interactions
Morphine may interact with other medicines. Always inform your doctor and pharmacist of all medications, supplements, and herbal products you are taking. Key interactions include:
- Benzodiazepines and other CNS depressants (fatal respiratory depression risk)
- MAOIs (contraindicated — can cause severe hypertensive crisis or serotonin syndrome)
- Alcohol
- Naltrexone (blocks opioid effects)
New Zealand Prescribing Information
Morphine is a Class B2 controlled drug in New Zealand. It is available in multiple formulations: immediate-release tablets/solution (Sevredol®, Morphine Sulfate oral liquid) and modified-release capsules/tablets (Kapanol®, MS Contin®). Prescriptions must comply with Controlled Drugs regulations. Palliative care teams typically manage complex morphine titration for end-of-life care.
Frequently Asked Questions
Will I become addicted to morphine?
Physical dependence (where stopping causes withdrawal) is likely with regular use, but this is different from addiction (compulsive drug-seeking behaviour). In legitimate pain management, morphine is used carefully and at the lowest effective dose. Discuss your concerns openly with your doctor.
Why do I need a laxative with morphine?
Opioids including morphine cause constipation by reducing bowel motility. Unlike most other side effects, constipation does not improve with time. Starting a regular laxative (e.g., lactulose or senna) at the same time as morphine prevents significant discomfort.
⚠️ 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: