• Morphine should be titrated in the same way as for pain relief, and the initial starting dose will depend on the person's previous exposure to opioids. For more information about the use of morphine in pain relief, see the CKS topic on Palliative cancer care - pain.
• For someone not already taking an opioid, a dose of 2.5 mg regularly every 4 hours, and as required, is suitable.
• For someone in whom a weak opioid (e.g. codeine or pholcodine) was ineffective, a dose of 5 mg to 10 mg regularly every 4 hours, and as required, should be used.
• If using 4-hourly morphine:
• After 1–2 days, calculate the total dose given over 24 hours, and use this to recalculate the 4-hourly dose. (The new 4-hourly and 'as required' dose is a sixth of the new total daily dose).
• Repeat this process every 1–2 days until the cough is controlled.
• Once a stable dose has been reached, this can be converted to once- or twice-daily modified-release morphine if preferred.
• For someone already taking a strong opioid such as morphine (for analgesia), do not try a weak opioid such as pholcodine or codeine. Instead, use an 'as required' dose of morphine to relieve cough.
• If an 'as required' dose relieves cough, either increase the regular daily dose by 30–50% every 2–3 days until symptoms are controlled or adverse effects prevent further dose increases, or continue to use additional morphine as required.
• If the total daily dose is increased, the 'as required' dose will also need to be recalculated. If an 'as required' dose of morphine does not relieve cough, there is little point continuing to increase the dose.
• Some people with cough but no pain can benefit from a dose of morphine at bedtime to prevent cough from disturbing sleep.

[Twycross et al, 2002]