Medicines & Supplements A to Z > Morphine


Last updated on 19/03/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  



BRAND NAME(S) IN HONG KONG: Morphine-Hameln, MST Continus

DRUG CLASS: Analgesic; Opioid 

USED FOR: Pain management

OTHER DRUGS IN THE SAME CLASS: Codeine, Fentanyl, Methadone, Oxycodone, Tramadol

– 10mg/5ml (syrups)
– 10mg/ml, 15mg/ml, 20mg/ml, 30mg/ml (injections)
– 10mg, 30mg, 60mg (prolonged-release tablets)

What is Morphine for?

Morphine is an opioid pain reliever (analgesic). It is a strong painkiller used to treat moderate to severe pain. Morphine works by blocking the transmission of pain signals through nerves.

How to use it?

Morphine can be taken by many different routes, including by intraspinal injection, intrathecal injection, intravenous injection, subcutaneous injection, intramuscular injection, rectal, and by mouth. Morphine Sulphate is the most common form of Morphine used in clinical practice.

If you are taking Morphine by mouth, the dose for the immediate-release medicines is 5-20 mg every 4 hours as needed, while the dose for the extended-release medicines is 10 mg every 12-24 hours.

If you are using Morphine rectally, you should use 10-20 mg every 4 hours.

The dosages above are just suggested dosages. The actual dosage should be individualised according to the severity of pain and your response.

What are the side effects of Morphine?

Common side effects of Morphine include constipation, dizziness and drowsiness, dry mouth, euphoric mood, flushing, hallucinations, nausea and vomiting (more common on initiation), respiration depression (with high dose). Like all opioid medications, people can become tolerant or addicted to Morphine, which can result in withdrawal symptoms when you try to stop the medicine.

Who should not take Morphine?

– People who are allergic to Morphine or any formulation ingredients.
– Patients with respiratory depression, serious bronchial asthma or gastrointestinal obstruction.
– People who are taking or took monoamine oxidase inhibitors (MAOIs) within the past 14 days.

Pharmacist Tips:

– Report if you experience severe side effects like dizziness.
– Note that opioids have the potential to be addictive and you can become tolerant over time.
– Do not discontinue abruptly if you have used Morphine over long periods of time.
– Do not break, chew or crush the extended release preparations. Swallow whole with water.
– For rectal preparations, remove the suppository from the package and moisten it with water for easier administration.
– Eat more high-fibre foods, drink more water and do more exercise to reduce the side effect of constipation.
– It is best to avoid alcohol while taking Morphine.

Common dosing schedule:
Can be taken with or without food.

This schedule is for reference only, adjustments may be made according to individual needs.

Some common medications Morphine may interact with:
– Antidepressants, e.g. Amitriptyline, Doxepin
– Antiplatelet agents, e.g. Aspirin, Clopidogrel
– Benzodiazepines, e.g. Lorazepam, Midazolam
– Medicines for lowering blood pressure, e.g. Atenolol, Verapamil
– Monoamine oxidase inhibitors, e.g. Selegiline

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Morphine in Hong Kong?

In Hong Kong, Morphine is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

Need more information?

For detailed information about the use of Morphine in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.