Treating moderate to severe pain

Opioids are commonly used for pain that is hard to ignore or feels very severe. Moderate pain may be a pain score of 4–6 (out of 10), and moderate to severe pain may be a score of 6–10.

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There are many different types of opioids, and these need to be prescribed by a doctor.

Codeine is often used for moderate pain. Codeine is broken down in the body into morphine. However, one in 10 people find they don’t get any pain relief as they cannot convert codeine. If taking Panadeine® or Panadeine Forte® does not offer more relief than paracetamol, let your doctor know as you may need other opioids.

Strong opioids, such as morphine, oxycodone, hydromorphone, methadone and fentanyl, are often effective for moderate to severe pain, and can be used safely if taken as prescribed.

Opioids either release the morphine slowly and control your pain for long periods, or release the morphine quickly to control pain for short periods.

Working out the dose

As people respond differently to opioids, the dose is worked out for each person based on their pain level. It’s common to start at a low dose and build up gradually until the pain is well controlled. Sometimes this can be done more quickly in hospital or under strict medical supervision.

Opioids commonly used for moderate to severe pain

Slow release

  • morphine – MS Contin®, Kapanol®, MS Mono®
  • oxycodone – OxyContin®, Targin®
  • hydromorphone – Jurnista®
  • tramadol – Tramal/Tramal®  SR, Zydol/Zydol™ SR
  • fentanyl – Durogesic®

Immediate release

  • morphine – Ordine®, Anamorph®, Sevredol®
  • oxycodone – OxyNorm®, Endone®, Proladone®
  • hydromorphone – Dilaudid®
  • fentanyl – Actiq®
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Side effects of opioids

Opioids can affect people in different ways. It can take a few days to adjust to taking strong pain medicines. You may have some of the following side effects:

Constipation – Most people regularly taking opioid medicines experience trouble passing stools (constipation). Your treatment team will suggest or prescribe a suitable laxative to take at the same time as the pain-killers. You may also be given a stool softener. Other ways to help manage constipation include drinking 6–8 glasses of water a day, eating a high-fibre diet and getting some exercise, but these may be difficult if you’re not feeling well.

Drowsiness – Feeling sleepy is typical, but this usually lasts for only a few days until the pain relief dose is stable. Tell your doctor or nurse if it lasts longer as you may have to change medicines. Alcohol is likely to increase drowsiness and is best avoided. You may need to take precautions when driving. See Can I drive while using opioids.

Tiredness – Your body may feel physically tired, so you may need to ask family or friends to help you with household tasks or your other responsibilities. Rest is important, but it’s also beneficial to do some light exercise or activity, such as stretches or going for a short stroll. This helps you maintain a level of independence and can give you some energy.

Feeling sick – This usually passes when you get used to the dose, or can be relieved with other medicines. Sometimes a change in the type of opioid is necessary.

Dry mouth – Opioids can reduce the amount of saliva in your mouth, which can cause tooth decay or other problems. Chewing gum or drinking plenty of liquids can help. Visit your dentist regularly to check your teeth and gums.

Itchy skin – If you have itchy skin, sometimes it may feel so irritating that it is painful. A moisturiser may help, or ask your doctor if there is an anti-itch medicine available or if you can try a different opioid for your pain.

Poor appetite – You may not feel like eating. Small, frequent meals or snacks and supplement drinks may help. If the loss in appetite is ongoing, see a dietitian for further suggestions.

Confusion or hallucinations – This is rare. It is important to tell your doctor immediately if this occurs.

Physical dependence – If you stop taking opioids suddenly, you will usually have withdrawal symptoms or a withdrawal response. This may include agitation, nausea, abdominal cramping, diarrhoea, heart palpitations and sweating. To manage the chance of side effects, your doctor will decrease your dose gradually to allow your body to adjust to the change in medicine. Don’t reduce your dose or stop taking opioids without talking to your doctor first.

Talk to your health care team often about any side effects you’re having. If needed, they can change your medicines or the doses.

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Common questions about opioids

Most people have questions about taking opioid medicines. 

If you are caring for someone with cancer pain, you may have additional questions about opioids.

Will I become addicted to opioids?

No – when people take morphine or other opioids only to relieve pain, they are unlikely to become addicted to the medicines. However, after some time, the body gets used to opioids and if they are stopped suddenly, people may have withdrawal symptoms. This means you have developed a tolerance, but it is not a sign of addiction.

Health professionals will closely monitor your use to maintain effective pain relief and avoid potential side effects. They will adjust the dose if necessary. However, a person who has already had a drug addiction problem may be at risk of addiction if opioids are used for cancer pain relief.

Taking opioids for pain relief is different to an addiction. Someone with a drug addiction problem takes drugs to satisfy physical or emotional needs, despite the drugs causing harm.

Will I need to have injections?

Not necessarily, medicines can be taken in different ways. Strong pain relievers are usually given by mouth in either liquid or tablet form. If you’re vomiting, opioids can be given via the rectum as a suppository, by a small injection under the skin (subcutaneously), using a skin patch or in lozenge form. 

Opioids can be injected into a vein for short-term pain relief, such as after surgery. This is called intravenous opioid treatment and is given in hospital.

If I start opioids too soon, will they be less effective later?

Some people try to avoid taking pain medicine thinking it is better to hold out for as long as possible so it works better later. However, this usually makes the situation worse because the pain perception of the brain and nervous system changes and pain becomes entrenched, needing more opioids. It is better to take medicine as prescribed rather than just at the time you feel the pain.

If I’m given opioids, does that mean my cancer is advanced?

People with cancer at any stage can develop severe pain that needs to be managed with strong pain medicine, such as morphine. If you have a strong pain-killer, this doesn’t mean you will always need to take it. If your pain improves, you may be able to take a milder pain-relieving drug.

What if I get breakthrough pain?

While breakthrough pain is relatively common among people diagnosed with cancer, this sudden flare-up of pain can be distressing.

You might get breakthrough pain even though you’re taking regular doses of medicine. This breakthrough pain may last only a few seconds, several minutes or hours. It can occur if you’ve been more active than usual or you’ve strained yourself. Sometimes there seems to be no reason for the extra pain.

You need to talk to your health care team who will advise you on how to cope with breakthrough pain. They will usually suggest you take your pain medicine as well as another drug to help with the breakthrough pain. An extra, or top-up, dose of a short-acting opioid (immediate release opioid) will be prescribed to treat the breakthrough pain. The dose works fairly quickly, in about 30–40 minutes.

It is helpful to keep a record of how many extra doses you need so your doctor can monitor your overall pain management. If you find your pain increases with some activities, taking an extra dose of medicine beforehand may help.

– Kate

Will the opioids still work if my body gets used to them?

People who have used opioids for a long time will sometimes become tolerant to the original dose. This means their doctor will need to increase the dose to achieve the same pain relief. Your dose of opioids may also be increased if your pain gets worse. There is no benefit in saving the pain control until the pain is severe.

Can I drive while using opioids?

Doctors have a duty to advise patients not to drive if they are a risk to themselves or others. During the first days of treatment, you may be less alert, so driving is not recommended. Once the dose is stabilised, you may want to consider driving. Seek your doctor’s advice and keep the following in mind:

  • Don’t drive if you’re tired, you’ve been drinking alcohol, you are taking other medicine that makes you drowsy, or road conditions are bad.
  • If you have a car accident while under the influence of a drug, your insurance company may not pay out a claim.
  • Special rules and restrictions about driving apply to people with brain tumours, including secondary brain cancer, or people who have had seizures. For more information, talk to your doctor or download a copy of Brain Tumours and Driving: A guide for patients and carers from the Neurological Society of Australasia website,

Can I stop my medicine at any time?

You should only reduce your dose or stop taking opioids in consultation with your health care team. If your pain gets better, you may end up needing less or no pain medicine. Morphine and other opioids will need to be decreased gradually to avoid side effects that may occur if you were to stop taking them suddenly. Withdrawal side effects can include flu-like symptoms or nausea.

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Other medicines

You may be prescribed other medicines to help relieve your pain. These are known as adjuvant drugs or adjuvant analgesics because they are prescribed with opioids. While they are not designed to control pain, they may be used for this purpose, and they often work well for nerve pain. Adjuvant drugs can be added during any stage of diagnosis and treatment.

These medicines are usually given as a tablet or an injection into a vein.

Some adjuvant drugs take a few days to work, so opioids are used to control the pain in the meantime. If you are taking an adjuvant drug, it may be possible for your doctor to lower the dose of the opioids. This may mean that you experience fewer side effects without losing control of the pain. Ask your doctor if the adjuvant drugs are likely to cause side effects.

Drug type (class)

Generic names

Type of pain


  • amitriptyline
  • doxepin
  • nortriptyline
  • duloxetine

burning nerve pain, peripheral neuropathy pain, electric shocks


  • carbamazepine
  • valproate
  • gabapentin
  • pregabalin

burning or shock-like nerve pain


  • lorazepam
  • diazepam
  • clonazepam

muscle spasms with severe pain


  • prednisone
  • dexamethasone

headaches caused by cancer in the brain, or pain from nerves or the liver


  • pamidronate
  • clodronate
  • zoledronate

bone pain (may also help prevent bone damage from cancer)

GABA (gamma- aminobutyric acid)

  • baclofen

muscle spasm, especially with spinal cord injury

human monoclonal antibodies

  • denosumab

bone pain (may also help prevent bone damage from cancer)

local anaesthetic*

  • lignocaine

severe nerve pain

*requires careful monitoring

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This information was last reviewed in September 2015
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