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Morphine in Cancer Pain Management

Some common misconceptions

Cancer girlPatient: “Hi Dr A, I am here for my follow up for my high blood pressure and diabetes. By the way, I was admitted to hospital for back pain last month. After all the investigations, they found that I have advanced cancer that has spread to my spine. I am undergoing chemotherapy and radiation therapy to my spine now. I was started on syrup morphine for my pain. I am very concerned about the morphine. I need your advice!”


This may be a common scenario faced by many family physicians who manage chronic conditions in heartland clinics. Like chronic illnesses, the number of patients with cancer is likely to increase with an ageing population in Singapore. In fact, cancer is now the most common cause of death in Singapore, accounting for about 30% of all deaths in 2011.

Cancer pain is one of the commonest symptoms in advanced cancers. Strong opioids such as morphine, oxycodone (OxyNorm®, OxyContin®, TARGIN®) and fentanyl patch (Durogesic®) are commonly prescribed for cancer pain management in the outpatient setting. Cancer patients are often fearful of the side effects and may consult their family physicians regarding their concerns. It is important for family physicians to address their concerns or misconceptions so that the patients may be compliant with the pain management programme from the hospital’s specialists.

Let’s look at some common concerns or misconceptions about the use of morphine or other strong opioids in cancer pain management.


All cancer patients suffer from severe cancer pain.

Patient: “Dr A, my father has been suffering from advanced cancer for the last three months and is still on chemotherapy in the hospital. I don’t understand why he doesn’t suffer from any pain. Could this be a wrong diagnosis? Shouldn’t all cancer patients have severe cancer pain?”


Explanation: Not all patients with advanced cancer suffer from cancer pain. A study has suggested that about one-quarter of such patients do not suffer from any pain. Approximately one-quarter of patients with advanced cancer have no pain, one-quarter have mild pain, one-quarter have moderate pain and only one-quarter have severe pain from cancer.


Vials and SyringeMISCONCEPTION #2

All cancer pains are managed by morphine or other strong opioids.

Patient:Why didn’t the hospital specialist give my mother morphine for her cancer pain? Instead, she was given panadol and celecoxib.”


Explanation: Morphine or other strong opioids are just one category (Step 3) of medications used to control cancer pain. Based on the World Health Organization’s (WHO) 3-Step Analgesic Ladder for Cancer Pain Relief, mild cancer pain can be managed with Step 1 drugs (non-opioids) such as paracetamol and/or non-steroidal anti-inflammatory drugs (NSAIDs) such as diclofenac, naproxen and celecoxib. Step 2 drugs (weak opioids) such as codeine and tramadol are used for moderate cancer pain. For severe cancer pain, Step 3 drugs such as morphine, oxycodone or fentanyl are used.


If there is neuropathic pain, drugs such as gabapentin or pregabalin (Lyrica®) may be used in addition to the drugs mentioned above.


Morphine has many intolerable side effects.

Patient: My friends have warned me about the many intolerable side effects of morphine, including respiratory depression.”

Explanation: For patients who require morphine or strong opioids for cancer pain, the three common possible side effects are initial drowsiness, nausea and vomiting, and constipation.  These can be easily managed.

  • Initial drowsiness may be experienced when morphine or other strong opioid is first started or when the dose is increased. This usually improves after a few days. If drowsiness persists and/or is severe, the dose could be reduced or stopped.
  • Nausea and vomiting only affects about one-third of patients on morphine or strong opioids. This can be managed with anti-emetic drugs such as metoclopramide or domperidone.
  • Opioid-induced constipation is usually easily relieved with common laxatives such as sennokot, lactulose or Forlax®. TARGIN®, which contains sustained-release oxycodone and naloxone, can be used in patients with severe opioid-induced constipation.


Respiratory depression is really more a toxicity than a side effect. It is very rare for patients on oral opioids. It may happen when a higher dose of opioids is given parenterally (intravenous or intramuscular injection etc.) in a short period of time, such as during a procedure or when worsening renal function leads to reduced elimination of the opioids.



Taking morphine regularly for cancer pain may lead to addiction.

Patient: “Dr A, I am worried about taking morphine. I don’t want to become a drug addict!”


Explanation: Patients who are taking morphine or strong opioids for cancer pain under the advice of an experienced doctor do NOT become addicted. Morphine taken on a regular basis to control cancer pain is NOT an addiction. When the pain is relieved by other means, such as radiotherapy for cancer bone pain, the morphine dose can be reduced significantly or even stopped.


If opioids are taken for reasons other than those advised by doctors, then an addiction problem may occur. For example, heroin, an opioid, is one of the most commonly abused drugs in Singapore, where addicts seek the “high” or euphoria effect.



Morphine should only be used as a last resort, especially when death is near.

Patient: Dr A, some relatives have advised me not to give my mother morphine except when it is a last resort, especially when death is near.”


Explanation: The use of morphine or strong opioids should be on the basis of pain management and not the proximity to death. Many patients who are far from death have significant pain relief from strong opioids. When pain control improves, quality of life improves.


Some patients have died after morphine was started.

Patient: Dr A, I am afraid about my mother being on morphine. My uncle, who was seriously ill with advanced cancer last year, was given morphine in the hospital and he died the next day.”


Explanation: The use of morphine or strong opioids does not lead to death, especially if it is started at a low dose and is increased gradually. However, when a strong opioid is started or increased when a patient is very ill and dying from a life-threatening disease, blame is put on morphine or the strong opioid when the patient subsequently dies. The patient will die from the life-threatening illness, whether morphine or other strong opioid is given. However, morphine or strong opioid used here is likely to relieve pain and breathlessness during the dying phase.



All patients who are dying should be given morphine or strong opioid to ensure that they will not suffer from any pain.

Patient: My father is dying in the hospice from advanced cancer. He is in a coma now and I am told he is in his last days. He is not in pain and is not on morphine or any analgesic. I have asked the hospice doctor to put him on morphine to ensure he will not suffer any pain even though he is in a coma, but the doctor refuses.”


Explanation: Not all patients who are dying are in pain or are distressed. Therefore, morphine or strong opioids may not be required for some dying patients. In fact, taking strong opioids when they are not required may result in unnecessary side effects.


The use of morphine or strong opioids in cancer pain management is not unusual. Family physicians should be familiar with the common misconceptions of the use of morphine and strong opioids, to reassure their patients who are on it.



Dr Kok Jaan Yang is a Specialist in Palliative Medicine in private practice. He is the Senior Consultant with Parkway Cancer Centre, practicing in Gleneagles Hospital, Mount Elizabeth Hospital and Mount Elizabeth Novena Hospital. He is also a Visiting Consultant in Dover Park Hospice and Singapore Cancer Society’s Home Hospice Services. Dr Kok is a Clinical Senior Lecturer with the NUS Yong Loo Lin School of Medicine, teaching medical students in palliative medicine.    
Posted by ezyhealth on Apr 13 2015. Filed under Myth Busters. You can follow any responses to this entry through the RSS 2.0. Both comments and pings are currently closed.

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