Can You Take Naproxen with METHOCARBAMOL?
A plain-English look at the major interaction between Naproxen (Pediapharm Naproxen Suspension 25 mg/mL (Medexus Pharma, Canada)) and METHOCARBAMOL (Methocarbamol) — what it means, why it happens, and what to talk to your doctor or pharmacist about.
Taking Naproxen (Pediapharm Naproxen Suspension 25 mg/mL (Medexus Pharma, Canada)) with METHOCARBAMOL (Methocarbamol) is a major drug interaction that should be avoided. Excessive sedation, respiratory depression, falls. Additive CNS depression. Both classes cause sedation and respiratory depression through complementary pathways.
Not sure about your specific combination? Check it in the Drug Interaction Checker →
Key Takeaways
- Interaction severity: Major
- Risk: Excessive sedation, respiratory depression, falls.
- Mechanism: Additive CNS depression. Both classes cause sedation and respiratory depression through complementary pathways.
- Naproxen: S4 in Australia, low risk
- METHOCARBAMOL: S4 in Australia, low risk
- Claims action: Flag for immediate prescriber review. Document intervention in claim file.
Naproxen vs METHOCARBAMOL at a Glance
| Property | Naproxen | METHOCARBAMOL |
|---|---|---|
| Brand names | Pediapharm Naproxen Suspension 25 mg/mL (Medexus Pharma, Canada), Proxen SR 750, Naprosyn SR750 | Methocarbamol |
| Drug class | opioid | muscle relaxant |
| Risk level | low | low |
| TGA Schedule (AU) | S4 | S4 |
Why Is This Combination Dangerous?
Additive CNS depression. Both classes cause sedation and respiratory depression through complementary pathways.
Regulatory Guidance by Jurisdiction
Australia TGA / SIRA / WorkSafe
The TGA and Australian Medicines Handbook classify this as a major drug interaction requiring immediate intervention.
United Kingdom NICE / MHRA / FPM
UK clinical guidelines recommend caution with this combination. For personal injury claims, the prescribing rationale should be documented and reviewed against NICE and FPM guidance.
United States FDA / CDC / State WC
The CDC and FDA recommend monitoring concurrent CNS depressant use. State workers compensation formularies may restrict or require prior authorization for this combination.
What Claims Professionals Should Do
- Flag immediately as a high-risk prescribing pattern in the claim file
- Request urgent prescriber review with documented clinical justification for the combination
- Consider an independent medical examination if the prescriber cannot provide adequate justification
- Assess work capacity impact as the combination significantly increases sedation and impairment risk
- Document all interventions for audit trail and compliance purposes
- Check Reasonable and Necessary status for both medications against the compensable injury
Clinical reference
A clinical summary of Naproxen and METHOCARBAMOL drawn from regulator advisories, national guidelines, and authoritative drug references. Read this if you want the deeper clinical picture before talking to your prescriber or pharmacist.
Severity assessment
Informational. While no direct drug-drug interaction is explicitly identified, both medications can cause central nervous system (CNS) depression, leading to additive effects such as drowsiness and dizziness.
Mechanism (plain English)
Methocarbamol is a muscle relaxant that works by depressing the central nervous system, which can lead to drowsiness and reduced alertness. Its exact mechanism of action is not fully understood, but it is thought to reduce nerve impulses that cause muscle spasms. Naproxen is a nonsteroidal anti-inflammatory drug (NSAID) that works by blocking substances in the body called prostaglandins, which are involved in pain and inflammation. Naproxen primarily acts on peripheral tissues to reduce pain, fever, and inflammation, but it does not have significant CNS depressant effects like methocarbamol. The theoretical concern arises from the potential for additive CNS effects if a patient is particularly sensitive or taking other CNS depressants, as methocarbamol can potentiate the effects of other CNS depressants.
Evidence level
Theoretical. There is no specific regulator-flagged or guideline-supported interaction for methocarbamol and naproxen. The concern is theoretical based on the known side effect profiles of each drug, particularly the CNS depressant properties of methocarbamol.
Top regulator advisories (cite verbatim or close paraphrase)
- TGA (Australia): No pair-specific public advisory found. Applicable product information for naproxen (e.g., ANAPROX 550, ARTG 66544) and methocarbamol (if available in Australia) would advise on individual drug risks. For naproxen, general warnings include gastrointestinal (GI) adverse events (bleeding, ulceration, perforation) and cardiovascular thrombotic events. For methocarbamol, general warnings include CNS depression.
- MHRA / NICE (UK): No specific guidance found for this pair. General warnings for naproxen (e.g., from MHRA products database) include GI and cardiovascular risks. For methocarbamol (e.g., from Medicines.org.uk), warnings include potentiation of CNS depressants and alcohol.
- FDA / CDC (US): No specific interaction advisory found for methocarbamol and naproxen. The FDA label for methocarbamol (ATMEKSI, Reference ID: 5634522) states: "ATMEKSI may potentiate the effects of CNS (central nervous system) depressants and alcohol." The FDA label for naproxen (NAPRELAN, Reference ID: 4148955) carries a boxed warning for serious cardiovascular thrombotic events (e.g., myocardial infarction and stroke) and serious gastrointestinal adverse events (e.g., bleeding, ulceration, and perforation).
- EMA (Europe): No specific interaction advisory found. General product information for each drug would apply.
Clinical risk factors that elevate the danger
Patients taking other CNS depressants (e.g., opioids, benzodiazepines, alcohol) concurrently with methocarbamol may experience enhanced drowsiness and dizziness. Patients with a history of gastrointestinal bleeding, ulcers, cardiovascular disease, or renal impairment are at higher risk for adverse effects from naproxen. Elderly patients are generally more susceptible to both CNS depressant effects and NSAID-related adverse events.
What a patient should be told
- You might feel more drowsy or dizzy than usual when taking these medications together. Be careful when driving or operating machinery until you know how they affect you.
- Do not stop taking either medication suddenly without talking to your doctor or pharmacist first.
- Watch out for warning signs like severe dizziness, extreme sleepiness, confusion, or stomach pain, black or tarry stools, or unusual bruising/bleeding. If you experience these, contact your healthcare provider.
- Discuss any concerns about drowsiness or other side effects with your doctor or pharmacist. They may be able to suggest safer alternatives or adjust your dosage.
- Seek urgent medical care if you experience chest pain, shortness of breath, sudden weakness on one side of your body, slurred speech, or severe abdominal pain.
Top 3 sources (with full citation)
- U.S. Food and Drug Administration. (2025). ATMEKSI (methocarbamol) oral suspension prescribing information. Reference ID: 5634522. https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/219843s000lbl.pdf
- U.S. Food and Drug Administration. (2017). NAPRELAN (naproxen sodium) controlled-release tablets prescribing information. Reference ID: 4148955. https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/020353s034lbl.pdf
- Drugs.com. Methocarbamol with Naproxen. https://www.drugs.com/drug-interactions/methocarbamol-with-naproxen-1588-0-1690-0.html
Notes for the reviewing pharmacist
While no direct, clinically significant interaction between methocarbamol and naproxen is widely reported or regulator-flagged, the potential for additive CNS depression should be considered, especially in patients who are elderly, taking other CNS depressants, or have underlying conditions that predispose them to sedation. The Drugs.com interaction checker reports no interaction, but this should be interpreted with caution, as it does not preclude theoretical or less common interactions. The primary risks associated with this combination would stem from the individual side effect profiles of each drug: CNS depression from methocarbamol and gastrointestinal/cardiovascular risks from naproxen. Patient counseling should focus on managing these individual risks and monitoring for signs of excessive sedation or NSAID-related adverse events. There is no evidence to suggest a pharmacokinetic interaction between these two drugs.
Source metadata JSON
Check this medication against your full medication list
Check all interactions for Naproxen and METHOCARBAMOL across your claimant's full medication list.
Allmeds AI Pharmacist scans interactions, schedules, and risk flags across your entire medication profile in minutes. Free for individuals; team plans for case managers, insurers, and schemes.
Related Resources
Important: This page is general health information, not personal medical advice. If you have questions about your medication — including starting it, stopping it, changing the dose, or combining it with something else — speak with your doctor or pharmacist. For an emergency or suspected overdose, call your local emergency number or poison information service immediately. Information is drawn from regulator and clinical guideline sources (TGA, FDA, MHRA, NICE, PBS, CDC); see our methodology for details.