Morphine and other medicines

Medically reviewed by Dr Roger Henderson, words by Helen Marshall, BPharm, MRPharmS
·2-min read
Photo credit: LaylaBird - Getty Images
Photo credit: LaylaBird - Getty Images

From Netdoctor

Morphine sulphate is a strong painkiller. It is a type of medicine known as an opioid analgesic or opiate. Opioid analgesics work by mimicking the action of natural pain-reducing compounds called endorphins, which are produced in the brain and spinal cord.

Find out which medicines you can have while also taking morphine:

Morphine and other painkillers

It's fine to take non-prescription painkillers like paracetamol, ibuprofen and aspirin with morphine. These are weaker painkillers, but work in a different way to morphine so can be used alongside it. There's no point in taking other opioids like codeine or co-codamol with morphine though, since they work in the same way and can also have similar side effects.

But, if you find you're still getting pain despite taking morphine you should talk to your doctor, who may either increase your morphine dose or try you on a different painkiller.

Morphine and other medicines

It's important to tell your doctor or pharmacist if you're already taking any medicines, including those bought without a prescription and herbal medicines, before you start treatment with morphine. Similarly, check with your doctor or pharmacist before taking any new medicines with morphine, to make sure that the combination is safe.

You're more likely to get side effects such as drowsiness, sedation, low blood pressure or slow, shallow breathing, if you take other medicines that have a sedative effect on the central nervous system with your morphine, for example:

  • antihistamines that cause drowsiness, eg chlorphenamine, hydroxyzine

  • antipsychotics, eg haloperidol, risperidone, olanzapine

  • barbiturates, eg phenobarbital, amobarbital

  • benzodiazepines, eg diazepam, temazepam

  • muscle relaxants, eg baclofen

  • other opioid painkillers, eg codeine, tramadol, oxycodone, fentanyl

  • pregabalin

  • sleeping tablets, eg zopiclone

  • tricyclic antidepressants, eg amitriptyline.

You're more likely to get side effects such as constipation and difficulty passing urine if you take other medicines that can cause these type of side effects with morphine, for example:

  • antihistamines that cause drowsiness

  • antimuscarinic medicines for Parkinson's symptoms, eg procyclidine, orphenadrine, trihexiphenidyl

  • antimuscarinic medicines for urinary incontinence, eg oxybutynin, flavoxate, tolterodine, propiverine, trospium

  • antispasmodics, eg atropine, hyoscine

  • some antisickness medicines

  • some antipsychotic medicines

  • tricyclic antidepressants, eg amitriptyline.

Cimetidine may reduce the breakdown of morphine and increase its level in the blood. This may increase the risk of side effects such as drowsiness and breathing difficulties with morphine, so don't take this with morphine unless advised to by your doctor or pharmacist.

Morphine may oppose the effects of the following medicines on the gut:

  • domperidone

  • metoclopramide.

Morphine may increase the blood level of gabapentin.

The following medicines may reduce the amount of morphine in the blood and could make it less effective at relieving pain:

  • rifampicin

  • ritonavir.

Last updated: 14.11.2020

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