Can I take Diazepam and Morphine together?
Drug interaction guide
Originally published 25 Jan 2026
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Taking diazepam and morphine together can cause extreme sleepiness, very slow or shallow breathing, and difficulty staying awake. In severe cases, this combination can lead to a coma or be life-threatening.
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Why this happens
Both drugs are 'central nervous system depressants'. This means they both slow down brain activity and the signals that tell your body to breathe. When taken together, their effects add up, making the sedation and breathing problems much stronger than if either drug were taken alone.
What you should do
Back to contentsYou should only take these two medicines together if they have been specifically prescribed by the same doctor who is aware you are taking both. If you must take both, use the lowest dose possible for the shortest time. Seek emergency medical help immediately if you experience extreme dizziness, fainting, very slow breathing, or if you cannot stay awake. Avoid alcohol and do not drive or operate machinery while taking this combination.
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Important precautions
Back to contentsRespiratory conditions (e.g. COPD, severe asthma) or sleep apnoea
Both medicines can significantly slow your breathing. Taking them together, or if you already have lung problems, can cause life-threatening breathing difficulties.
Long-term use (Dependence)
These medicines are highly addictive. Using them for more than a few weeks can lead to physical dependence and severe withdrawal symptoms if stopped suddenly.
Driving and operating machinery
It is often an offence to drive while taking diazepam as it can seriously impair your coordination and reaction times. Do not drive or operate machinery until you know how this medicine affects you, and always keep the medicine in its original packaging to show the police if stopped.
Pregnancy
Avoid use in late pregnancy or during labour, as it can cause 'floppy infant syndrome' and life-threatening withdrawal symptoms in the newborn.
Food and drink warnings
Back to contentsAlcohol
It is best to avoid or strictly limit alcohol while taking diazepam. Combining them can cause dangerous levels of drowsiness, breathing difficulties, and may lead to a coma. It also significantly increases the risk of accidents.
It is best to avoid or strictly limit alcohol while taking morphine. Combining alcohol with morphine significantly increases the risk of dangerous side effects, such as extreme sleepiness, breathing difficulties, and a potentially fatal overdose.
Grapefruit juice
Avoid drinking grapefruit juice or eating grapefruit while taking diazepam. Grapefruit contains compounds that stop your body from breaking down the medicine properly, which can lead to higher levels of the drug in your blood and increase the risk of side effects.
Caffeine (Coffee, tea, energy drinks)
Caffeine can reduce the calming effects of diazepam. Because caffeine is a stimulant and diazepam is a sedative, they work against each other, making the medicine less effective.
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Using other medicines
Back to contentsTaking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.
Disclaimer
This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.
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Article history
The information on this page is written and peer reviewed by qualified clinicians.
25 Jan 2026 | Originally published

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