Ondansetron

5-HT3 antagonist antiemetic

Also sold as Zofran, Zofran ODT.

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Findings for this medication

Research about this medication, graded for how strongly each finding can be attributed to it. Nothing here describes your own levels.

Ondansetron has no established nutrient-depletion mechanism. It is extensively metabolized in the liver (CYP3A4 predominant, with CYP1A2 and CYP2D6), only about 5% of a dose appears unchanged in urine, and the two FDA label texts read contain no nutrient, mineral or antacid interaction [1][2]. The one mechanism class that is present in weak form is altered gut transit: multiday dosing slows colonic transit and constipation is labeled at 9% to 11% of chemotherapy patients [1][2], but no source read connects that to any nutrient. Red and orange tiers are therefore empty. Ondansetron's own 5-HT3 receptor antagonism, its dose-dependent QT prolongation and the nausea or vomiting it treats are not nutrient findings and are not graded as such.

5-HT3 antagonist antiemetic · ATC A04AA01 · also sold as Zofran and Zofran ODT (+ generics) · reviewed 2026-10-04. This describes research about the medication. It does not say anything about your own levels or health.

How to read the evidence grades

These colours describe how strongly a finding can be attributed to the medication in the research. They are not a severity score and they say nothing about your own health.

Grades describe how strongly a finding can be attributed to Ondansetron in the research — not how common it is, how serious it would be, and not anything about you personally.

Red — Severe: Two or more independent Tier A sources, this drug in the cohort, the nutrient directly measured, consistent direction, clinically meaningful magnitude, a named mechanism, no substantial contradicting Tier A evidence.
Orange — Moderate: At least one Tier A source with this drug in the cohort showing a real but bounded deficit: an exposure window, a subgroup, low frequency, or a functional rather than circulating deficit.
Yellow — Low: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction.
Not graded — disclosed evidence gap: Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result.Source definition: Not gradeable under the rules above because nothing has been measured. Published as a documented gap, never as reassurance that there is no effect.

What the research found

Magnesium and potassium status as a QT-risk modifier - interaction runs from electrolyte to drug

Yellow — Low

See study details

Low magnesium or potassium raises the risk of ondansetron-associated QT prolongation and torsades de pointes; this is a drug-safety interaction, not evidence that ondansetron lowers either mineral.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. yellow

Limits on what this shows

Key negative/null findings: No study located measured magnesium after ondansetron. The case report states electrolyte imbalance as a contributing risk factor and does not attribute the low values to the drug [5].
At-risk subgroups: Patients with vomiting, diarrhea or poor intake, congenital long QT, heart failure, bradyarrhythmia, or co-medication with other QT-prolonging drugs; higher IV doses carry greater QTc effect [1][2].

Regulatory status

Labeled. Ondansetron prolongs the QT interval dose-dependently, with postmarketing torsades de pointes; hypokalemia and hypomagnesemia are named risk factors, and ECG monitoring is recommended with electrolyte abnormalities, congestive heart failure, bradyarrhythmias or other QT-prolonging drugs [1][2]. The label advises avoiding use in congenital long QT syndrome [1].

Population evidence

Tier A for the interaction statement (label). Case-level Tier B: Tafish et al. 2025 report a 43-year-old woman with nausea and vomiting who received 8 mg IV ondansetron with pre-administration magnesium 1.57 mg/dL (reference 1.9 to 2.5), potassium 3.54 mmol/L (borderline low) and calcium 8.16 mg/dL, then developed QTc 582 ms, torsades de pointes and cardiac arrest, with full recovery after resuscitation and electrolyte correction [5]. No effect estimate or CI exists; this is one case.

Mechanism

Named: hypokalemia and hypomagnesemia independently lengthen cardiac repolarization, and ondansetron adds dose-dependent QTc prolongation (32 mg over 15 minutes gave a maximum of 19.5 ms in the label study) [1]. The electrolyte abnormality here preceded the dose.

Overlap

Shares the label with the Potassium entry; see Overlap map.

Counter-evidence held on record

The electrolyte abnormality in the one case report preceded the dose and coexisted with vomiting, so it is condition-linked (confounding by indication) rather than drug-caused [5]. Single case, no denominator. Direction caution (Hard Rules 4 and 5): this is an electrolyte-to-drug safety interaction. It must not be read as ondansetron depleting magnesium or potassium, and no supplement or dose is recommended here; correction of abnormal values is a prescriber decision made before dosing.

Potassium - rare labeled postmarketing hypokalemia, one null prospective measurement

Yellow — Low

See study details

The label lists rare postmarketing hypokalemia; a small prospective pediatric study measured no change in plasma potassium after a dose, and the case-level literature is confounded by vomiting and chemotherapy.

Full detail and limits

Limits on what this shows

Key negative/null findings: Plasma potassium unchanged (p=0.774); authors conclude ondansetron does not cause significant potassium wasting in appropriately hydrated, nutritionally replete patients [4].
At-risk subgroups: Patients with vomiting, diarrhea, diuretic use or protracted illness, who were excluded from the Fiedrich cohort [4]; these conditions lower potassium independent of ondansetron.

Regulatory status

Labeled in postmarketing experience as "rare cases of hypokalemia" (injection label, section 6) [1]. No frequency given.

Population evidence

Tier A null: Fiedrich et al. 2012, prospective cohort of 10 pediatric oncology patients (12 recruited) on IV chemotherapy with planned ondansetron prophylaxis, measured mean plasma potassium 3.9 +/- 0.3 mmol/L before and 3.9 +/- 0.2 mmol/L after (p=0.774); no patient developed hypokalemia; urine potassium fell significantly (p=0.019); only 5 of 10 were analyzable for the transtubular potassium gradient [4]. Case-report titles on ondansetron-associated hypokalemia appear in a PubMed listing (2008, 2016, 2022) but their abstracts could not be opened and they are not relied on [16].

Mechanism

Absent as a named mechanism. Fiedrich found reduced, not increased, urinary potassium loss, which argues against renal potassium wasting [4]. The label states no tubular or intracellular-shift mechanism.

Counter-evidence held on record

Small sample (n=10), single dose, short observation window, no magnesium measured, and the authors could not assess specific chemotherapy combinations or pre-existing tubular dysfunction [4]. Confounding by vomiting, chemotherapy agents and hydration status is presumed until excluded (Hard Rule 6). Rare-event context flag only. This is not an established depletion and should never prompt a potassium supplement based on ondansetron use alone; low potassium found on testing is managed by the prescriber, and its link to ondansetron is unproven.

The five body-system areas

Each finding is counted once, in a single area. Where a study is mentioned in a second area it is context only.

Mitochondrial Burden

Each finding below is counted once, in this area only.

Mitochondrial burden - receptor-level blockade in cells and a protective sepsis-model signal, no damage signal

Yellow — Low

See study details

Ondansetron at 3 nM blocked serotonin-evoked mitochondrial membrane potential and oxygen consumption responses in transfected cells and isolated mitochondria, and in a septic cardiomyopathy model it preserved mitochondrial integrity; neither finding shows mitochondrial harm in treated people.

Full detail, limits and 2 references

Limits on what this shows

Key negative/null findings: Wang 2026 did not test ondansetron alone in healthy controls, so baseline mitochondrial effects are unknown [8]. An earlier cardiac-mitochondria patch-clamp study (Wang 2016) used a different 5-HT3 antagonist, not ondansetron, and measured no downstream metabolism, so it is excluded [9].
At-risk subgroups: None established in humans.

Regulatory status

Not addressed in the FDA labels read [1][2].

Population evidence

Tier B, in vitro and animal only. Rao et al. 2023 used HEK293T cells transfected with 5-HT3A and/or 5-HT3E subunits and isolated mitochondria; 3 nM ondansetron pretreatment significantly suppressed the serotonin-induced rise in mitochondrial membrane potential signal and reduced oxygen consumption (p<0.01 in 5-HT3A-expressing cells) [7]. Wang et al. 2026 used neonatal rat cardiomyocytes (ondansetron 25 and 75 micromolar) and LPS or cecal-ligation sepsis in C57BL/6 mice (0.25 and 1 mg/kg): ondansetron restored mitochondrial integrity, improved JC-1 membrane potential, raised OPA1 and MFN2, and reduced MitoSOX superoxide [8].

Mechanism

Named and equal to the drug's own pharmacology: antagonism of 5-HT3 receptors reported on mitochondria in a transfected-cell system [7]. Blocking a serotonin-evoked response is the intended receptor action, not a deficiency or injury mechanism (Hard Rule 2).

Overlap

Rao 2023 also underlies ATP production; Wang 2026 also underlies Oxidative stress and Iron; see Overlap map.

Counter-evidence held on record

Transfected HEK293T cells overexpress receptors, concentrations in Wang 2026 (25 to 75 micromolar) far exceed therapeutic plasma levels, and no human mitochondrial measurement exists. Reverse-direction and receptor-mechanism findings only. Must never be presented as mitochondrial damage or as a reason to take any mitochondrial supplement; no dose is recommended.

Wang et al. Ferroptosis in septic cardiomyopathy is alleviated by ondansetron: the critical role of the HTR3A-ATF3 axis in mitochondrial and oxidative homeostasis. Biomedicines. 2026;14(5):1040. PMID 42193366. — Neonatal rat cardiomyocytes plus LPS and cecal-ligation sepsis in mice, ondansetron specific. Tier B.No healthy-control arm for ondansetron alone.
Wang et al. 5-HTR3 and 5-HTR4 located on the mitochondrial membrane and functionally regulated mitochondrial functions. Sci Rep. 2016. — Mouse cardiac mitoplast patch-clamp.Excluded: ondansetron was not tested (a different 5-HT3 antagonist, 3-AQC, was used). Cited only to show it was checked and rejected.

Oxidative Stress

Each finding below is counted once, in this area only.

Oxidative stress - protective direction in one disease model, no adverse redox signal verified

Yellow — Low

See study details

In a mouse and rat-cardiomyocyte sepsis model ondansetron lowered lipid peroxidation and raised glutathione; no study opened measured redox markers in ondansetron-treated people or in healthy animals.

Full detail, limits and 2 references

Limits on what this shows

Key negative/null findings: No healthy-control arm, so baseline redox effects of ondansetron are unmeasured [8]. A 2019 mouse study titled "Ondansetron enhanced diclofenac-induced nephrotoxicity" (PMID 31332906) appeared in a PubMed listing; its abstract could not be opened, so its direction on oxidative markers is unverified and it is not relied on [13].
At-risk subgroups: None established.

Regulatory status

Not addressed in the FDA labels read [1][2].

Population evidence

Tier B, animal and in vitro. Wang et al. 2026: ondansetron decreased MDA, increased GSH, reduced ROS (DCFH-DA), and increased SOD2 and SIRT3 expression in LPS-challenged cardiomyocytes and septic mice [8]. All effects were in the protective direction.

Mechanism

Proposed by the authors as the HTR3A-ATF3 axis with anti-ferroptotic effects (reduced ACSL4 and PTGS2; raised SLC7A11 and GPX4) [8]; unconfirmed in humans.

Overlap

Same source as Mitochondrial burden and Iron; see Overlap map.

Counter-evidence held on record

One study, one model, supratherapeutic concentrations, and an unread opposing-title listing item. Reverse-direction finding. It does not show that ondansetron is antioxidant in patients, and it must not be paired with any antioxidant supplement recommendation.

Copper and Iron Balance

Copper and iron are assessed separately. Nothing here is counted twice.

Iron - cellular labile iron lowered in a sepsis model, reverse direction, no systemic iron data

Yellow — Low

See study details

In septic cardiomyopathy models ondansetron reduced intracellular Fe2+ overload; this is a cellular ferroptosis readout in a disease model, not a measure of iron status, absorption or stores.

Full detail, limits and 1 references

Limits on what this shows

Key negative/null findings: Interaction checkers report no interaction between ondansetron and iron (Tier D, context only) [23]. No iron-status study in ondansetron users was located; PubMed "ondansetron iron" returned 9 results, none measuring iron status [18].
At-risk subgroups: None established.

Regulatory status

Not addressed in the FDA labels read; no iron interaction in the label text [1][2].

Population evidence

Tier B, animal and in vitro. Wang et al. 2026 reported reduced Fe2+ overload by FerroOrange staining alongside restored GPX4 and SLC7A11 in cardiomyocytes and septic mice [8]. No ferritin, transferrin saturation, serum iron or hemoglobin was reported in the extract read.

Mechanism

Anti-ferroptotic signaling (HTR3A-ATF3 axis) per the authors; unconfirmed [8].

Overlap

Same source as Mitochondrial burden and Oxidative stress; see Overlap map. Independent of the Copper entry.

Counter-evidence held on record

Cellular labile iron in a disease model is not body iron status; one study; no healthy control. Do not read this as an iron effect of ondansetron in either direction. No iron supplement or dose is recommended, and iron status testing is a clinical decision independent of this drug.

Wang et al. Ferroptosis in septic cardiomyopathy is alleviated by ondansetron: the critical role of the HTR3A-ATF3 axis in mitochondrial and oxidative homeostasis. Biomedicines. 2026;14(5):1040. PMID 42193366. — Neonatal rat cardiomyocytes plus LPS and cecal-ligation sepsis in mice, ondansetron specific. Tier B.No healthy-control arm for ondansetron alone.

Copper

Not graded — disclosed evidence gap

See study details

Copper

Full detail and limits

What the grade means here: Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result. ungraded

Limits on what this shows

Why no grade: Dual condition met: no Tier B or Tier C evidence was located for ondansetron and copper, and no circulating claim about ondansetron and copper was found to rebut as white. This is a disclosed evidence gap, not a finding of safety.

Channels tried

PubMed search listing "ondansetron copper": 31 results returned, none about copper status or metabolism (the top 10 were antiemetic pharmacology in animal models, an inflammasome paper and a natural-product study) [12]. Web search ("ondansetron serum iron copper zinc levels"): no ondansetron-specific copper source. DailyMed/FDA labels: read for [1][2], no copper content. Crossref REST search: HTTP 429 via WebFetch, HTTP 403 on CONNECT via curl. Europe PMC REST: HTTP 429 (WebFetch; not retried per the gateway notice), HTTP 403 on CONNECT (curl). OpenAlex search: HTTP 429 (WebFetch), HTTP 403 on CONNECT (curl, including single-record lookup). Semantic Scholar API: HTTP 429 (WebFetch), HTTP 403 on CONNECT (curl). PubMed eutils (curl): HTTP 403 on CONNECT. Unpaywall: HTTP 403 on CONNECT (curl). Direct publisher/PMC pages: PMC returned bot-verification pages for three articles.

Assessment

One clean, non-blocked PubMed zero-relevance result plus a clean web-search miss, with residual uncertainty from the blocked channels. A later revision should re-run copper and ceruloplasmin queries on Europe PMC and Crossref when access returns.

Gut Microbiome Risk

Each finding below is counted once, in this area only.

Gut microbiome risk - rat phylum shift with ondansetron alone, no human data

Yellow — Low

See study details

In rats, oral ondansetron alone shifted gut bacterial phyla (more Bacteroidetes, fewer Firmicutes); no human microbiome measurement in ondansetron users was located.

Full detail and limits

Limits on what this shows

Key negative/null findings: PubMed "ondansetron microbiota" returned 8 results, of which only Feng 2019 tested ondansetron on gut microbiota [14]. A large in vitro screen of more than 1,000 marketed drugs against 40 gut strains does not mention ondansetron in its retrievable text, so it gives no data either way [10].
At-risk subgroups: None established; chemotherapy patients have large independent microbiome disruption.

Regulatory status

Label: multiday dosing slows colonic transit; constipation 9% to 11% and diarrhea up to 16% in chemotherapy adults [1][2]. These are labeled gut effects, not microbiome measurements.

Population evidence

Tier B, animal. Feng et al. 2019: Sprague-Dawley rats, n=6 per group across 6 groups including an ondansetron-only group (1.3 mg/kg by gavage); 16S rDNA sequencing showed Bacteroidetes increased and Firmicutes decreased in ondansetron and gingerol groups versus control, and UniFrac analysis separated the 6 groups [6]. Group sizes are small and the abstract-level extract gave no effect sizes or CIs.

Mechanism

Hypothesized only: slowed colonic transit [1] and altered serotonergic signaling in the gut could shift community composition; the paper does not establish causation [6].

Overlap

Context shares the label gut-transit statements with no other entry as evidence; see Overlap map.

Counter-evidence held on record

Rodent gavage dose, small groups, cisplatin-model context in the same study, and no human or clinical-outcome link. A rodent composition shift is not a functional deficit and must not be read as microbiome harm in people or as support for probiotic or other product recommendations.

Oxygen and ATP Output

Oxygen delivery and ATP production are assessed separately. Nothing here is counted twice.

ATP production - inferred from serotonin-evoked respiration blockade, ATP itself not measured

Yellow — Low

See study details

The only energy-adjacent ondansetron data are reduced serotonin-evoked oxygen consumption in transfected cells and isolated mitochondria; no ATP measurement for ondansetron was located.

Full detail, limits and 1 references

Limits on what this shows

Key negative/null findings: PubMed "ondansetron ATP mitochondrial respiration" returned zero results (clean zero, 2026-10-04) [21]; the shorter query "ondansetron ATP" was rate-limited and not retried.
At-risk subgroups: None established.

Regulatory status

Not addressed in the FDA labels read [1][2].

Population evidence

Tier B, in vitro. Rao et al. 2023: ondansetron 3 nM suppressed serotonin-induced oxygen consumption in 5-HT3A and 5-HT3A plus 5-HT3E expressing HEK293T cells and in isolated mitochondria [7]. Oxygen consumption is a respiration proxy; ATP content or synthesis was not reported in the extract read. Wang 2026 reported membrane potential and fusion markers, not ATP [8].

Mechanism

Receptor-mediated modulation of serotonin-evoked respiration, which is the drug's intended receptor action in this system [7]; no mechanism for reduced cellular energy output is described.

Overlap

Same single source as Mitochondrial burden (Rao 2023); one data point read two ways. See Overlap map.

Counter-evidence held on record

Not an ATP measurement; transfected-cell system; reduced evoked respiration was a blockade of an agonist response, not a basal energy deficit. Do not report as impaired energy production. No energy-related supplement or dose is recommended.

Wang et al. Ferroptosis in septic cardiomyopathy is alleviated by ondansetron: the critical role of the HTR3A-ATF3 axis in mitochondrial and oxidative homeostasis. Biomedicines. 2026;14(5):1040. PMID 42193366. — Neonatal rat cardiomyocytes plus LPS and cecal-ligation sepsis in mice, ondansetron specific. Tier B.No healthy-control arm for ondansetron alone.

Oxygen delivery/utilization

Not graded — disclosed evidence gap

See study details

Oxygen delivery/utilization

Full detail, limits and 1 references

What the grade means here: Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result. ungraded

Limits on what this shows

Why no grade: Dual condition met: no Tier B or Tier C source reports ondansetron effects on hemoglobin, hematocrit, red-cell mass, arterial oxygenation or tissue oxygen delivery, and no circulating claim about oxygen-carrying capacity for ondansetron was found. The label notes ondansetron distributes into erythrocytes [1] without any hematologic effect statement. Cell-level oxygen consumption data are filed under Mitochondrial burden and ATP production, not here. Ondansetron's QT and hemodynamic label content is its own cardiac pharmacology and is not an oxygen-delivery finding (Hard Rule 2).

Channels tried

PubMed search listing "ondansetron hemoglobin": 12 results, none showing a hemoglobin or oxygen-delivery effect; one 2021 item on drug-induced immune hemolytic anemia and direct antiglobulin testing (PMID 33277206) appeared, but its abstract could not be opened (page returned no content) and ondansetron's role in it is unknown [19]. Web search for methemoglobinemia, anemia or hemoglobin decrease with ondansetron: a 2026 pediatric case report states ondansetron was given as symptomatic therapy and was not implicated, with the three suspected agents being benzocaine, lidocaine with chlorhexidine and co-trimoxazole [11]. Crossref, Europe PMC, OpenAlex, Semantic Scholar: same 429 and 403 results as listed under Copper. DailyMed/FDA labels read [1][2].

Assessment

Mostly a genuine gap, with one unresolved PubMed listing item (PMID 33277206) that a later revision must open. Treat as partially tooling-limited until that record is read.

PubMed search listing: ondansetron hemoglobin (opened 2026-10-04). — Search-listing page only (12 results). PMID 33277206 (immune hemolytic anemia, 2021) listed but its page returned no content; ondansetron role unknown.

Claims checked and not supported

These circulate online for this medication. They are listed here only so they can be answered, never as findings, and they are not graded.

A claim with no supporting evidence is not necessarily disproven. Where evidence actually argues against a claim, that is stated below.

Magnesium wasting caused by ondansetron
Where it comes from: Inference from electrolyte-imbalance warnings in consumer drug pages and from case reports of ondansetron cardiac events that list low magnesium alongside the dose [24][5]. No page opened states the claim outright.
Why it fails: The label names hypomagnesemia as a risk factor that precedes dosing, so the stated direction is magnesium affecting ondansetron safety, not the reverse [1][2]. In the one case report with values, magnesium was 1.57 mg/dL before the dose was given [5]. No study located measured magnesium after ondansetron, and the one prospective electrolyte study did not measure it [4]. No mechanism for renal or gut magnesium loss is described. The drug-interaction page opened reports no known interaction between magnesium and ondansetron [25].

How the body handles this medication

Metabolism and CYP450: Extensively metabolized; about 5% of a radiolabeled dose recovered as parent drug in urine. Substrate of CYP1A2, CYP2D6 and CYP3A4, with CYP3A4 predominant. The label text read does not state that ondansetron induces or inhibits any CYP enzyme; that absence in the retrieved text is not asserted as a finding.Zofran FDA labels, section 12.3 [1][2]
Inducer interactions (direction: other drugs affect ondansetron): Phenytoin, carbamazepine and rifampin increase ondansetron clearance (rifampin: AUC and half-life reduced by about 48% and 46% as retrieved); no dose adjustment recommended. Direction is drug-to-ondansetron, not a nutrient effect.Zofran injection label, section 7 [1]
Absorption and food: Oral bioavailability about 56% for an 8 mg tablet; food slightly enhances bioavailability (magnitude not retrieved). No absorption transporter named in the text read. Women show greater absorption and higher plasma concentrations than men.Zofran oral tablet label, section 12.3 [2]
Elimination and impairment: Mean half-life 3.5 h (19 to 40 y), 4.7 h (61 to 74 y), 5.5 h (75 y or older). Hepatic impairment: clearance reduced 2-fold to 3-fold, half-life 11.6 h (mild to moderate) and about 20 h (severe). Severe renal impairment: clearance reduced about 41%, no adjustment.Zofran injection label, section 12.3 [1]
Renal tubular handling of electrolytes: No tubular effect stated in the label text read. A prospective pediatric study (n=10) measured plasma potassium unchanged after a dose and urine potassium lower, not higher.Label [1][2]; Fiedrich 2012 [4]
Gut transit and mineral or antacid interactions: Multiday administration slows colonic transit; constipation 11% (multiday, 2021 injection label) and 9% versus under 1% placebo (2016 oral label); diarrhea 16% in chemotherapy adults. No mineral or antacid interaction appears in the label text read.Zofran FDA labels, sections 6, 7, 12.2 [1][2]

What the research says is worth watching

General information from the medication label and the studies above. It is not personal medical advice, and any change belongs with your prescriber.

Before IV or high-dose use
Serum potassium and magnesium, ECG
The label recommends ECG monitoring in patients with electrolyte abnormalities, congestive heart failure, bradyarrhythmias or other QT-prolonging drugs, and advises avoiding use in congenital long QT syndrome [1][2]. Abnormal electrolytes found are corrected by the prescriber; this is a safety check, not a depletion finding.
At-risk groups
Vomiting, diarrhea, poor intake, diuretics
These conditions, not ondansetron, are the established drivers of low potassium and magnesium in the people who receive it [4][5]. Pre-existing losses make the QT interaction more likely.
Ongoing
Bowel activity
Multiday use slows colonic transit and may mask progressive ileus; monitor decreased bowel activity in patients at risk of GI obstruction [1]. This is a labeled safety point, not a nutrient finding.
Dosing context
Hepatic impairment, age, sex
Exposure rises with hepatic impairment (clearance down 2-fold to 3-fold), age over 75, and in women [1][2]. These alter drug exposure, not nutrient status.
Supplement separation
No interval documented
No supplement or mineral separation interval appears in the label text read. Interaction checkers list none for vitamin B12 or iron [22][23], and one lists St John's wort as possibly speeding ondansetron breakdown without serious effect (Tier D) [24]. No supplement dose appears anywhere in this dossier.
Special populations
Pregnancy, renal impairment, children
Severe renal impairment reduces clearance about 41% with no adjustment; children aged 4 to 18 clear the drug faster than adults [1]. Hyperemesis-related nutritional deficits belong to the condition, not the drug, and are managed under standard obstetric care.
Revisit when access improves
Copper, oxygen delivery, hypokalemia case reports
Re-run Europe PMC, Crossref and OpenAlex queries for copper and hematologic effects, open PMID 33277206, and open the three hypokalemia case-report abstracts (PMIDs 18176182, 27730793, 36798103).

Overlap map, to prevent double counting

Mitochondrial burden
Shares evidence with: ATP production
Note: Both rest on the single Rao et al. 2023 transfected-cell and isolated-mitochondria study (ondansetron 3 nM, serotonin-evoked membrane potential and oxygen consumption) [7]. One data point read two ways; not two confirmations. ATP itself was not measured.
Mitochondrial burden
Shares evidence with: Oxidative stress, Iron
Note: All three cite Wang et al. 2026, one septic cardiomyopathy study that reported mitochondrial integrity, MDA/GSH/ROS and Fe2+ readouts from the same mice and cells [8]. Count as one study with three readouts, not three independent lines.
Potassium
Shares evidence with: Magnesium and potassium as a QT-risk modifier
Note: Both draw on the same Zofran label electrolyte and QT text [1][2]. The first is a possible drug effect on potassium; the second is the reverse-direction interaction. Do not add the label twice as independent support.
Magnesium and potassium as a QT-risk modifier
Shares evidence with: Fails verification (magnesium wasting)
Note: The same Tafish 2025 case report (pre-dose magnesium 1.57 mg/dL) supports the interaction entry and the rebuttal [5].
Gut microbiome risk
Shares evidence with: none as evidence
Note: Cites the label gut-transit and constipation statements only as context [1][2]; the graded evidence is Feng 2019 alone [6].
Copper, Iron
Shares evidence with: none
Note: Independent entries (Hard Rule 7). No source supports both; Iron rests on Wang 2026 and Copper has no qualifying evidence.
Oxygen delivery/utilization, ATP production
Shares evidence with: none
Note: Independent entries. Oxygen consumption data from [7] are used only in the ATP and Mitochondrial entries and are not counted as oxygen-delivery evidence.

All references used above

Ondansetron

Findings for this medication

What the research found

Magnesium and potassium status as a QT-risk modifier - interaction runs from electrolyte to drug

Potassium - rare labeled postmarketing hypokalemia, one null prospective measurement

The five body-system areas

⚡Mitochondrial Burden

Mitochondrial burden - receptor-level blockade in cells and a protective sepsis-model signal, no damage signal

💥Oxidative Stress

Oxidative stress - protective direction in one disease model, no adverse redox signal verified

⚖️Copper and Iron Balance

Iron - cellular labile iron lowered in a sepsis model, reverse direction, no systemic iron data

Copper

🌿Gut Microbiome Risk

Gut microbiome risk - rat phylum shift with ondansetron alone, no human data

💨Oxygen and ATP Output

ATP production - inferred from serotonin-evoked respiration blockade, ATP itself not measured

Oxygen delivery/utilization

Claims checked and not supported

Magnesium wasting caused by ondansetron

How the body handles this medication

What the research says is worth watching

Overlap map, to prevent double counting

Mitochondrial Burden

Oxidative Stress

Copper and Iron Balance

Gut Microbiome Risk

Oxygen and ATP Output