Tramadol is a commonly used centrally acting analgesic associated with seizures and suspected to cause serotonin toxicity in overdose.
This study sought to investigate the effects of tramadol overdose, and included evaluation for serotonin toxicity based on the Hunter Serotonin Toxicity Criteria where the seven clinical features of spontaneous clonus, inducible clonus, ocular clonus, agitation, diaphoresis, tremor and hyperreflexia are examined for in all patients taking serotonergic medications; seizures and central nervous system depression.
This was an observational cases series based on a retrospective review of tramadol overdoses (> 400 mg) admitted to a tertiary toxicology unit from November 2000 to June 2013. Demographic details, information on ingestion (dose and co-ingestants), clinical effects, complications (seizures, serotonin toxicity and cardiovascular effects) and intensive care unit (ICU) admission were extracted from a clinical database.
There were 71 cases of tramadol overdose (median age: 41 years, range: 17-69 years; and median ingested dose: 1000 mg, interquartile range [IQR]: 800-2000 mg). Seizures were dose related and occurred in 8 patients, one of them co-ingested a benzodiazepine compared with 16 patients without seizures. There were no cases of serotonin toxicity meeting the Hunter Serotonin Toxicity Criteria. Tachycardia occurred in 27 and mild hypertension occurred in 32. The Glasgow Coma Score was < 15 in 29 and < 9 in 5 patients; three co-ingested tricyclic antidepressants and two tramadol alone (3000 mg and 900 mg). Respiratory depression occurred in 13, median dose: 2500 (IQR: 1600-3000) mg which was significantly different (p = 0.003) to patients without respiratory depression, median dose: 1000 (IQR: 750-1475) mg. Eight patients were admitted to ICU, five due to co-ingestant toxicity and three for respiratory depression.
Tramadol overdose was associated with a significant risk of seizures and respiratory depression in more severe cases, both which appear to be related to the ingested dose. There were no cases of serotonin toxicity, while opioid-like effects and adrenergic effects were prominent.
Tramadol overdose is associated with seizures and respiratory depression, but is unlikely to cause serotonin toxicity.
Pharmacology, Toxicology and Pharmaceutical Science
17
12%
Nursing and Health Professions
11
8%
Neuroscience
6
4%
Biochemistry, Genetics and Molecular Biology
4
3%
Other
14
10%
Unknown
50
35%
Attention Score in Context
Attention Score in Context
This research output has an Altmetric Attention Score of 26. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 26 September 2025.
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#1,878,347
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Outputs from Clinical Toxicology (15563650)
#267
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Outputs of similar age
#19,360
of 307,406 outputs
Outputs of similar age from Clinical Toxicology (15563650)
#2
of 21 outputs
Altmetric has tracked 33,928,890 research outputs across all sources so far. Compared to these this one has done particularly well and is in the 94th percentile: it's in the top 10% of all research outputs ever tracked by Altmetric.
So far Altmetric has tracked 2,648 research outputs from this source. They typically receive a lot more attention than average, with a mean Attention Score of 17.0. This one has done well, scoring higher than 89% of its peers.
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We're also able to compare this research output to 21 others from the same source and published within six weeks on either side of this one. This one has done particularly well, scoring higher than 90% of its contemporaries.
