Reviewed by MedNext Clinical Team
Tramadol is one of the most frequently prescribed analgesics in primary and secondary care, yet it is also one of the most misunderstood. Unlike traditional opioids, tramadol has a dual mechanism of action that creates unique risks many prescribers do not anticipate [1].
Dual Mechanism and Serotonergic Risk
Tramadol is both a weak mu-opioid receptor agonist and a serotonin-norepinephrine reuptake inhibitor (SNRI). This serotonergic activity makes it capable of precipitating serotonin syndrome, particularly when co-prescribed with other serotonergic agents such as SSRIs, SNRIs, MAOIs, tricyclic antidepressants, or triptans [1]. Serotonin syndrome can present with agitation, hyperthermia, clonus, and autonomic instability — a combination that can be life-threatening if not recognised promptly.
Seizure Risk
Tramadol lowers the seizure threshold, and this risk is dose-dependent. Seizures have been reported even at therapeutic doses, particularly in patients with a prior history of epilepsy, head injury, or those taking other epileptogenic drugs. The combination of tramadol with antidepressants further amplifies this risk through additive serotonergic effects.
CYP2D6 Metabolism
Tramadol is metabolised by CYP2D6 to its active O-desmethyltramadol (M1) metabolite, which is responsible for most of its opioid effect. CYP2D6 poor metabolisers may experience inadequate analgesia, while ultra-rapid metabolisers are at risk of opioid toxicity from excessive M1 production [1]. CYP2D6 inhibitors such as fluoxetine, paroxetine, and bupropion can significantly alter tramadol's efficacy and safety profile.
Controlled Drug Status and Dependence
Tramadol is now classified as a Schedule III controlled drug in many jurisdictions, reflecting growing evidence of its abuse potential. Dependence can develop even with therapeutic use, and abrupt withdrawal produces both opioid-type and SNRI-type symptoms. When discontinuing tramadol after prolonged use, a gradual taper is strongly advised.
Key Prescribing Considerations
- Avoid co-prescribing with SSRIs, SNRIs, or MAOIs due to serotonin syndrome risk
- Use with caution or avoid in patients with epilepsy
- Consider CYP2D6 status and inhibitor co-medications
- Limit duration of prescribing; taper when stopping after prolonged use
- Follow controlled drug prescribing requirements applicable in your jurisdiction
References
- Miotto K, et al. Trends in tramadol: pharmacology, metabolism, and misuse. J Pain. 2017;18(1):1-10.