Analgesia is the process of providing pain relief. Effective analgesia is provided by understanding the underlying cause of the pain. Inflammatory pain is treated with non-steroidal anti-inflammatory drugs (NSAIDs) or opioids, whereas neuropathic pain, which is characterised by burning, tingling or electric shock type sensations, is mainly treated with tricyclic antidepressant drugs (TCAs) or anti-epileptic drugs (AEDs).

For cancer pain, the most effective analgesia is provided by opioids. The World Health Organization’s guidance on the treatment of cancer pain is based upon the progressive use of increasingly potent analgesics, as demonstrated by its ‘analgesic ladder’, which involves the following three steps:

Step 1: Mild pain: non-opioid with or without adjuvant

Simple analgesics like paracetamol or ibuprofen will often suffice. Both drugs are available in different formulations, including dispersible tablets, liquids and suppositories. While NSAIDS are effective at combating inflammation, they can cause gastrointestinal side effects such as nausea, dyspepsia and even ulceration. Patients receiving regular NSAIDs may also be prescribed omeprazole (20mg) or another proton pump inhibitor (PPI) to protect against gastric bleeding. Adjuvant analgesics are drugs with other primary indications that are also effective at providing relief from pain. These include some antidepressants (mostly TCAs) and some AEDs.

Step 2: Mild to moderate pain: a weak opioid with or without a non-opioid or an adjuvant

Weak opioids such as codeine or dihydrocodeine with or without paracetamol (e.g. co-codamol) and/or an NSAID and, if appropriate, an adjuvant. Tramadol is often used in preference to codeine as it is less constipating and carries a lower risk of addiction, making it more appealing to patients.

Step 3: Moderate to severe pain: strong opioid with or without a non-opioid or an adjuvant

Morphine is often used to replace the weaker opioids – with or without paracetamol and/or NSAIDs. The combined use of modified release (MR) preparations (e.g. MST) plus immediate release (IR) (e.g. Oramorph) for breakthrough pain is usually effective for controlling pain in most patients.