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Can you take co-codamol with naproxen and diazepam?
Drug reviews: use, side effects, effectiveness

Can you take co-codamol with naproxen and diazepam?

Today I will review the use of three different drugs, which occasionally are prescribed at the same time or in combination with one another. This post aims to answer the following question: can you take co-codamol with naproxen and diazepam? As a part of the discussion, I will review a licensed use of each drug and reasoning for combination treatment. Remember to follow the directions given by your prescriber.

Table of Contents

  • Co-codamol: use, mechanism of action and common side effects 
  • Naproxen: use, mechanism of action and common side effects
  • Diazepam: use, mechanism of action and common side effects
  • Can you take co-codamol with naproxen?
  • Can you take naproxen and diazepam?
  • Can you take co-codamol with diazepam?

What is co-codamol?

Co-codamol is a popular painkiller available on prescription or over the counter (see Co-codamol over the counter) and one of the top drugs prescribed in the UK. Co-codamol contains two active ingredients, namely paracetamol and codeine (an opioid analgesic).  

Co-codamol – licensed use

Co-codamol is a painkiller, which is used to manage acute pain, not relieved by other painkillers, such as paracetamol or ibuprofen alone. The lower strength of co-codamol is widely available as a pharmacy-only medication. ‘Standard’ pharmacy-only co-codamol contains 500mg of paracetamol and 8mg of codeine per tablets (Co-codamol 8/500).

Some branded products, for example, Solpadeine max contains 12.8mg of codeine and 500mg of paracetamol per tablet.

Co-codamol – mechanism of action

The exact mechanism of action of paracetamol is not known. Codeine acts on opioid receptors and consequently affect the transmission of pain signals to the central nervous system.

Co-codamol – common side effects

Paracetamol on its own does not produce many side effects. Codeine, on the other hand, is associated with a few common side effects, for example:

  • Drowsiness and sedation
  • Nausea
  • Vomiting
  • Dry mouth
  • Constipation  

What is naproxen?

Naproxen is another popular prescription painkiller, which belongs to a group of drugs called non-steroidal anti-inflammatory drugs (NSAIDs). Another example of NSAIDs, which is commonly available over the counter from pharmacies is ibuprofen. Many naproxen alternative drugs exist and can be prescribed by a doctor. 

Naproxen– licensed use

Naproxen and other NSAIDs are used to help with pain and inflammation. Naproxen is the most commonly used NSAIDs as it offers good efficacy with a low incidence of side effects. Examples of licensed use for which NSAIDs can be prescribed:

  • Conditions characterised by pain and inflammation, including rheumatic disease (osteoarthritis, rheumatoid arthritis) and disorders affecting muscles and bones.
  • Acute gout
  • Painful menstruation

Naproxen – mechanism of action

NSAIDs, including naproxen, have a well-defined mechanism of action. NSAIDs stop production of prostaglandins, which play a role in the inflammation process. Increased level of prostaglandins is observed at the site of injury or infection. NSAIDs produce anti-inflammatory and pain relief effects.

Naproxen– common side effects

Naproxen can commonly cause gastro-intestinal side effect, for example:

  • Vomiting
  • Nausea
  • Heartburn / dyspepsia
  • Constipation / diarrhoea

Individuals who take other drugs or have an underlying condition(s) may be offered proton pump inhibitor (PPIs). Omeprazole (the most popular PPI) is often prescribed together with naproxen, to ‘protect’ the stomach and minimise gastro-intestinal side effects such as heartburn.  

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What is diazepam?

Diazepam differs to previously reviewed co-codamol and naproxen as it is not classified as a painkiller. Diazepam belongs to a group of drugs called benzodiazepines. Benzodiazepines are categorised as hypnotics (to help with help) and anxiolytics (to help with anxiety). Commonly diazepam is also known as ‘muscle relaxant‘. 

Diazepam – licensed use

Benzodiazepines can be used to manage various conditions. Benzodiazepines are usually prescribed as a shortterm treatment, due to their addictive properties (physical dependence) and tolerance (medication does not produce the same therapeutic effect as it initially did). Examples of conditions treated:

  • Muscle spasm
  • Anxiety
  • Insomnia
  • Sedation during dental procedures

Diazepam – mechanism of action

Diazepam’s exact mechanism of action is complex. In simple terms, diazepam acts in the central nervous system (brain), affecting the release of chemical substances called neurotransmitters. Benzodiazepines also decrease muscle spasm by stopping transmission of nerve cells (neurons) and other agents located in the spine and brain (Witenko et al., 2014). 

Diazepam – common side effects

Benzodiazepines, including diazepam, can produce many side effects. Common side effects include:

  • Drowsiness
  • Confusion
  • Loss control of body movements (ataxia)
  • Tremor
  • Fatigue
  • Withdrawal symptoms (sweating, tremor, panic, anxiety, palpitations, muscle spasm, loss of appetite)

I will now look at concomitant use of either of the drugs. As you may have deducted a combination of two or more of the above medicines may be used in painful conditions (co-codamol & naproxen) characterised by muscle spams (diazepam).

Can you take co-codamol with naproxen and diazepam?

GP can prescribe a combination of all three drugs at the same time. The logic behind the combination treatment is simple. All drugs work in a different way and when taken together produce a cumulative effect. Co-codamol and naproxen are used for its pain-relieving properties, whereas diazepam to manage muscle spasm.

Use of diazepam is one of the treatment options in managing muscle spasm as set by (national) the NICE guidelines, which sets recommendations for doctors and other healthcare professionals (NICE, 2020).

Diazepam can be prescribed on its own as a muscle relaxant or in combination with either co-codamol or naproxen. Perhaps, the use of naproxen and/or co-codamol to acute manage pain is more straight forward. Diazepam or another muscle relaxant is considered if muscle spasm is widespread or involving different ‘trigger points’ (ibid).

As an example, an individual who experiences lower back pain (without sciatica) may be offered in the first instance, an NSAID (naproxen). Codeine/co-codamol can be offered as an alternative to NSAIDs, if NSAIDs are not tolerated or ineffective. The guide on management of back pain advices against routine use of opioids for acute low back pain.

If muscle spasm is experienced, a GP may consider the use of diazepam. Diazepam would be prescribed on a short-term basis, 2-5 days. Although not contra-indicated, the guide on back pain advices against the use of opioids (co-codamol) at the same time with diazepam, due to increased risk of ‘lethal’ sedation. (NICE, 2020)

Despite the advice on possible increased sedation caused by taking both diazepam, co-codamol and naproxen as occasionally prescribed together. 

Can you take co-codamol with naproxen?

A GP or another prescriber can issue a prescription for a combination of co-codamol and naproxen. Both drugs do not interact with each other.

Can you take naproxen and diazepam?

The combination of naproxen and diazepam may be considered in acute conditions characterised by muscle spasm. There is no interaction between drugs.

Can you take co-codamol with diazepam?

 As previously reviewed the use of opioids such as co-codamol at the same time with diazepam is not recommended. Use of diazepam with opioids may result in severe sedation, respiratory depression, coma and death (eMC, 2019). Combination of both drugs should be considered for patients for whom other treatments and not possible. Combination of diazepam and opioids should be limited to a short time only.


Some patients may be prescribed a combination of co-codamol, naproxen and diazepam, after careful consideration of the treatment due to possible risk of severe side effects. A different mechanism of action for each drug may result in better pain and muscle spasm control. Patients need to be aware of sedative properties of both co-c0damol and diazepam and possible risk of severe sedation when a combination of those drugs is prescribed. 


eMC (2019). SmPC: Diazepam Tablets BP 10mg. Accessed on 28/01/2021

NICE (2020). Scenario: Managing muscle spasm pain. Available at: Accessed on 27/01/2021

Witenko, C., Moorman-Li, R., Motycka, C., Duane, K., Hincapie-Castillo, J., Leonard, P., & Valaer, C. (2014). Considerations for the appropriate use of skeletal muscle relaxants for the management of acute low back pain. P & T : a peer-reviewed journal for formulary management, 39(6), 427–435. Available at: Accessed on 27/01/2021

I am a community pharmacist working in UK. I blog about drugs, health and pharmacy.

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