Morphine

Indications

Morphine is a strong opioid painkiller. It is used for severe pain that other painkillers cannot control, such as pain after surgery or serious injury, pain from a heart attack, and cancer pain. In palliative care it is also used to ease breathlessness. It is a controlled medicine and is supplied only on a doctor's prescription.

How It Works

Morphine attaches to opioid receptors in the brain and spinal cord. This changes the way the body feels and responds to pain, so pain feels less intense.

Dosage and Administration

Morphine is taken only as prescribed. The dose is set by the doctor for each person and depends on how severe the pain is and whether the person has taken opioids before. Immediate-release tablets and oral solution usually work within an hour and are often given every 4 hours; modified-release (MR) tablets are usually taken every 12 hours and must be swallowed whole, never crushed, broken or chewed. Measure the oral solution with the syringe or cup provided. Injections are given by a doctor or nurse. Do not take extra doses or change the dose on your own. After regular use, do not stop suddenly; the doctor will reduce the dose slowly.

Interactions

Taking morphine with sedating medicines can slow breathing dangerously and can be fatal. These include benzodiazepines such as Diazepam, Alprazolam and Clonazepam, sleeping tablets, Gabapentin and Pregabalin, sedating antihistamines, antipsychotics, other opioids and alcohol. Do not take it with, or within 14 days of, an MAO inhibitor. Rifampicin can reduce its effect. Medicines such as Metoclopramide and some antidepressants may also interact; tell your doctor about all your medicines.

Contraindications

• Severe breathing problems or slow, shallow breathing, or an acute severe asthma attack.
• Blockage or paralysis of the bowel.
• Head injury or raised pressure in the skull, unless managed by a specialist.
• Acute alcohol poisoning, or taking an MAO inhibitor now or in the last 14 days.
• Allergy to morphine.

Side Effects

Very common: constipation (a laxative is usually needed), nausea, vomiting and drowsiness. Common: dizziness, dry mouth, sweating, itching, confusion and difficulty passing urine.

Get urgent medical help, or call emergency services, if the person has slow or shallow breathing, is very sleepy or cannot be woken, has very small (pinpoint) pupils, blue lips, fainting, severe constipation with tummy pain and swelling, or signs of allergy such as swelling of the face or difficulty breathing.

Pregnancy and Lactation

Use in pregnancy only if clearly needed and under close medical care. Regular use late in pregnancy can cause withdrawal symptoms in the newborn, and use during labour can slow the baby's breathing. Morphine passes into breast milk and can make the baby sleepy or slow its breathing; the doctor will decide whether you can breastfeed, and the baby should be watched closely.

Precautions and Warnings

Long-term use can lead to tolerance and dependence. Keep it locked away, never share it, and return unused medicine to a pharmacy. Use with care in older people, kidney or liver disease (lower doses are needed), low blood pressure, thyroid problems, an enlarged prostate, sleep apnoea and lung disease. Do not drink alcohol. It can cause drowsiness, so do not drive or use machines if affected.

Overdose

An overdose can cause pinpoint pupils, very slow or stopped breathing, extreme drowsiness, cold clammy skin, unconsciousness and death. Call emergency services straight away. Naloxone, given by medical staff, can reverse the effects.

Therapeutic Class

Strong opioid analgesic.

Storage

Store below 30°C, away from light, in a locked place out of the reach and sight of children. Use the oral solution within the time stated on the label after opening.