Tramadol

Limits on what this shows

• Null findings: Minimal effect at therapeutic and single toxic concentrations in isolated rat liver mitochondria [21]. Listing includes a rat dementia-model study in which tramadol appeared to restore mitochondrial enzymes [23] (not opened).
• At-risk subgroups: Not defined; human exposure studies are absent.

Direction

Direct mitochondrial interference (mechanism class E). Not a nutrient deficiency.

Regulatory status

Not mentioned in the retrieved label text [1][2].

Population evidence

Tier B only. Human renal proximal tubular cells [20]: complexes I and III activity, membrane potential and oxygen consumption fell, lactate release rose; Co-Q10 was protective in that model. Rat brain, 70 rats in 7 groups [22] (abstract reconstructed by OpenAlex): complexes I, III and IV fell and II was preserved; the abstract says this occurred at both dose levels in one passage and only above standard therapeutic doses in another, so the therapeutic-dose finding is internally inconsistent. Isolated rat liver mitochondria [21]: function and membrane potential fell at 100 and 300 micromolar, swelling at 300 micromolar; effects at therapeutic and single toxic concentrations were minimal. Listing [23] adds endometrial cancer cells (depolarization), mouse complex I inhibition on escalating doses (PMID 35829998, abstract not opened: PubMed and OpenAlex requests were refused with HTTP 429), and several rat tissue studies (listing only).

Mechanism

Present: inhibition of complexes I, III (and IV in brain) with ROS overproduction [20][21][22].

Counter-evidence held on record

Counter-evidence and confounding Cell lines and isolated organelles are exposed at fixed concentrations that may exceed tissue levels on therapy. Overdose and abuse models dominate. Shared evidence with oxidative stress and ATP entries. Framing caution A mechanistic research flag, not a finding that therapeutic tramadol damages mitochondria in people. No supplement recommendation (Co-Q10 was tested only in the cell model [20]).

Limits on what this shows

• Null findings: At therapeutic and single toxic concentrations the isolated rat liver mitochondria showed minimal change [21]. A rat renal ischemia-reperfusion study reports raised total oxidant status together with positive effects on antioxidant capacity, and a dementia-model study reports tramadol restoring some mitochondrial enzymes [24][23] (listing only, mixed direction).
• At-risk subgroups: Not defined. Exposures studied are supratherapeutic or abuse-pattern, plus alcohol co-misuse in one human listing record [24].

Direction

Tissue oxidative burden (excess ROS) with antioxidant enzyme consumption. Not a nutrient deficiency.

Regulatory status

Not mentioned in the retrieved label text [1][2].

Population evidence

Tier B only. Human renal proximal tubular cells [20]: EC50 9.8 and 11.5 micromolar; ROS and TBARS rose, catalase and SOD fell, glutathione fell. Isolated rat liver mitochondria [21], 1.7 to 600 micromolar: ROS and lipid peroxidation rose at 100 micromolar, protein carbonylation at 600 micromolar, glutathione fell at 600 micromolar; therapeutic and toxic single exposures showed minimal effects. Rat hippocampus [25]: 50 mg/kg intraperitoneal on 8 alternate days, hydrogen peroxide 1.28-fold, cysteine fell to 67% of control (summarizing fetch of the publisher page). Listing summaries [24] report higher MDA and lower SOD, GPx or GSH in rat cerebellum, kidney, brain and adrenal cortex, and a rabbit study, at 20 to 100 mg/kg (listing only, abstracts not opened; no human-equivalent dose conversion done).

Mechanism

Present: ROS generation linked to mitochondrial respiratory chain inhibition [20][21]. Human relevance at therapeutic exposure is not shown.

Counter-evidence held on record

Counter-evidence and confounding Shares its main sources with the mitochondrial and ATP entries (see Overlap map). Rodent doses and in vitro concentrations are not shown to match human therapeutic plasma levels. Many records are toxicity-protection studies built to produce damage. Framing caution Not a deficiency claim and not a reason to take antioxidant supplements. Protective-agent rodent studies (vitamins B12, C, D3, selenium) are addressed under Fails verification.

Limits on what this shows

• Null findings: [31] measured urinary copper and found no difference. Serum copper and ceruloplasmin were not measured in either study [32].
• At-risk subgroups: Not defined.

Direction

Urinary excretion lower in a mixed substance-use group. Direction for body copper status is unknown. Not a deficiency claim.

Regulatory status

Copper not found in the 2023 label text [1].

Population evidence

Substance-use-disorder study [30]: 74 patients using cannabis, tramadol, opium or combinations vs 60 healthy controls; urinary copper markedly lower in the patient group (the fetch summary printed values of 48.15 and 25.45 micrograms per liter and an 89.2% difference; which group held which value was not verified), zinc also lower, no difference between drug subgroups, confounders not described in the abstract. Egyptian male cohort [31]: 19 controls, 18 tramadol addicts, 28 tramadol plus cannabis; urinary copper and zinc not significantly different from controls. Both read as PubMed record summaries.

Mechanism

Absent. No chelation, enzyme or transport mechanism for copper was found for tramadol.

Counter-evidence held on record

Counter-evidence and confounding Polysubstance use, malnutrition, supratherapeutic dosing and differing methods confound urinary trace metals. The two studies disagree. Framing caution This is a disclosed context flag, not evidence that tramadol lowers copper. No copper testing or supplementation is indicated by this entry.

Limits on what this shows

• Null findings: No human iron, ferritin, anemia or methemoglobin signal was found. Searches: PubMed listings "tramadol iron status" (2 restless legs reviews, no iron measurement), "tramadol anemia" (19 records, none showing anemia or iron deficiency from tramadol), "tramadol hematological parameters hemoglobin" and "tramadol methemoglobinemia" [33], and, in the repair pass, "tramadol ferritin" (3 records: two restless legs reviews and [37]) and "tramadol serum iron" (only [37]); "tramadol hepcidin" and "tramadol addicts hematological iron" returned 404 pages. DailyMed 2023 label text: iron not found. A pediatric G6PD hemolysis paper (PMID 21784438, J Pediatr 2011) has no abstract in OpenAlex and was not opened. The two rat studies contradict each other in direction.
• At-risk subgroups: Not defined. Doses of 10 to 100 mg/kg in rats were not converted to human equivalents.

Direction

Mixed and unresolved. [37] shows higher serum iron (retention or release direction); [38] shows lower serum ferrous iron. Neither is an iron deficiency or a dietary-intake finding (Hard Rule 2). The increase in [37] runs opposite to depletion, so iron supplementation would not be the remedy and could be the hazard.

Regulatory status

Iron not found in the 2023 label text [1].

Population evidence

Tier B only, tramadol was in both cohorts. [37] Wistar rats, 6 per group, 10, 25 or 50 mg/kg intraperitoneal for 14 days: serum iron about 2.3-fold higher on average at almost all doses, ferritin about 1.6-fold higher, haptoglobin up to 2.3-fold, heme oxygenase-1 activity 11.2-fold at 50 mg/kg, transferrin lower at 25 and 50 mg/kg, hepcidin lower at 50 mg/kg; hemoglobin and total iron-binding capacity were not reported (publisher page read through a summarizing fetch, described there as the full paper; abstract also read via OpenAlex). [38] male Wistar rats, 8 per group, 50 or 100 mg/kg oral gavage daily for 30 days: serum ferrous iron lower by 73.31% and 65.54% (control iron value not stated); ferritin, hemoglobin and other iron indices were not measured (PDF read through a summarizing fetch).

Mechanism

No established mechanism for tramadol and iron handling. The authors of [38] attribute the fall to central effects of tramadol on metabolism, which is not demonstrated. In [37], higher ferritin, haptoglobin and heme oxygenase-1 occurred alongside liver and kidney damage, which can raise these markers on their own (acute phase and tissue injury), so a direct effect on iron handling is not separated from toxicity.

Counter-evidence held on record

Counter-evidence and confounding Toxicity-range rodent exposure, serum iron has strong diurnal and inflammatory variability, and the two studies differ in route, duration and direction. [37] also reports oxidative stress markers in the same animals (see Overlap map). Anemia or iron-deficiency outcomes in tramadol users were searched and not found. Framing caution Not an iron deficiency claim and not a reason to test or supplement iron. One study points to higher, not lower, circulating iron and ferritin; supplementation would be the hazard if that were real.

Limits on what this shows

• Null findings: Reviews describe tramadol as less constipating than strong opioids [34], and no tramadol microbiome study in humans was found [29].
• At-risk subgroups: Not defined.

Direction

Possible compositional change. Not a nutrient finding.

Regulatory status

Not mentioned in the retrieved label text [1][2]. Label constipation rates 24%, 38% and 46% at 7, 30 and 90 days [1].

CLASS EXTRAPOLATION and cohort test

Class: opioids. Review [27] (Biomedicines 2022, narrative, abstract read via OpenAlex) states opioid use alters gut bacterial composition and damages the epithelial barrier; its abstract does not name tramadol and the full text was not opened. Ten opioid and microbiota records in a PubMed listing [28]: the fetch tool found none that explicitly tested tramadol. Cohort test result: tramadol NOT confirmed in any studied cohort, so the class evidence is Tier C and capped at yellow.

Tramadol-specific evidence

One rat study [26] (6 weeks, surgical osteoarthritis model, tramadol vs celecoxib vs diclofenac): the abstract states tramadol analgesia persisted after antibiotic treatment whereas the NSAID effects disappeared; it gives no tramadol-specific composition, diversity or short-chain fatty acid data. Two listing summaries disagree on whether tramadol itself altered the microbiota, so no direction is assigned [29]. Other hits were plant and sludge studies, which are irrelevant.

Mechanism

Opioid-induced slowed transit and barrier effects are proposed for the class [27]. For tramadol, constipation is an outcome and also a competing explanation for any microbiome shift.

Counter-evidence held on record

Counter-evidence and confounding Constipation severity, diet, indication and other drugs confound any microbiome change. The Tier C review does not stratify by opioid. Framing caution Not a dysbiosis claim for tramadol. Opioid constipation is a documented drug effect to manage with a prescriber, not evidence of a microbiome or nutrient deficiency.

Limits on what this shows

• Null findings: No study measuring tissue or blood ATP, phosphocreatine or energy charge in tramadol-treated animals or humans was found in the listing [23].
• At-risk subgroups: Not defined.

Direction

Reduced cellular energy output as a downstream effect of respiratory chain inhibition. Not a nutrient deficiency.

Regulatory status

Not mentioned in the retrieved label text [1][2].

Population evidence

Tier B only. Human renal proximal tubular cells [20]: ATP production, oxygen consumption rate and membrane potential fell and lactate release rose, with cytotoxicity EC50 values of 9.8 and 11.5 micromolar. Rat liver mitochondria [21]: mitochondrial function fell at 100 and 300 micromolar; ATP was not named in the abstract text read.

Mechanism

Present: complex I and III inhibition [20].

Counter-evidence held on record

Counter-evidence and confounding Rests on the same source as the mitochondrial entry [20]. Cell-line cytotoxicity is not equal to an energy deficit in a patient. Framing caution Not a claim of low energy or fatigue from tramadol. No supplement recommendation.

Limits on what this shows

• Null findings: PubMed searches for tramadol with methemoglobinemia (1 irrelevant record) and with anemia (19 records, none showing tramadol-caused anemia; one G6PD hemolysis-risk study in children was listed but not read) found no mammalian signal [33].
• At-risk subgroups: Not defined. G6PD deficiency is listed as a studied group but results were not read.

Direction

Hematologic outcome in a non-mammalian model. Not an iron deficiency and not a nutrient finding (Hard Rule 2).

Regulatory status

The 2023 label text contained no mention of anemia, hemoglobin or methemoglobin [1].

Population evidence

Tier B only. Clarias gariepinus (catfish) sub-chronic tramadol exposure [33]: WBC, RBC, hemoglobin and PCV fell, MCH and MCHC rose, with raised oxidative stress (listing summary; abstract not opened). A rat study listed under hemoglobin showed lowered hemoglobin from quercetin, not from tramadol [33].

Mechanism

Not described in the material read; possibly secondary to oxidative stress in the same study.

Counter-evidence held on record

Counter-evidence and confounding Fish at environmental or toxic exposure, unknown translation. Shares a source with the oxidative stress entry. Framing caution No claim of reduced oxygen delivery in people taking tramadol. No supplement recommendation.