Meta Information
ID:l-carnitine
Name:
Schema Version:2.4_uniform_evidence_2026_06_18
Created
2026-05-21T22:30:00Z
Model
phase-a-upgrade-claude-sonnet-4.6
Interactions
Target id:
/class/anticoagulants-antiplatelets
Target name:
Anticoagulants and Antiplatelets (e.g., Warfarin)
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
L-Carnitine may enhance the effects of anticoagulant drugs like warfarin and acenocoumarol, significantly increasing the international normalized ratio (INR) and the risk of bleeding.
Actionable advice:
L-Carnitine supplementation should be avoided when taking anticoagulant medications unless approved and closely monitored by a physician.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
On the other hand, L-carnitine decreased fibrinogen, FVII, FDP, PAI-1, MDA, and platelet aggregation and increased PT, aPTT, coagulation time, protein C, ATIII, and antioxidants in diabetic rats.
Label source:
PubMed: Journal of physiology and biochemistry (2014)
Source url:
Exact phrase from label:
In this issue of Blood, Deguchi et al present evidence to support a novel role for acylcarnitines as anticoagulants.
Label source:
PubMed: Blood (2015)
Source url:
Exact phrase from label:
In summary, our study identified low plasma levels of acylcarnitines in patients with VTE and showed that acylcarnitines have anticoagulant activity related to an ability to bind and inhibit factor Xa.
Label source:
PubMed: Blood (2015)
Action type:
avoid
Target id:
/intervention/levothyroxine
Target name:
Thyroid Hormones (e.g., Levothyroxine)
Severity:
major
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
L-Carnitine can inhibit the transport of thyroid hormones (T3 and T4) into the cell nucleus, potentially reducing their effectiveness and worsening symptoms of hypothyroidism.
Actionable advice:
L-Carnitine should be avoided with hypothyroidism or when taking thyroid medication, as it can interfere with treatment.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Our data are consistent with carnitine being a peripheral antagonist of TH action, and they indicate a site of inhibition at or before the nuclear envelope.
Label source:
PubMed: Carnitine is a naturally occurring inhibitor of thyroid hormone nuclear uptake. (PMID 11201848)
Action type:
avoid
Target id:
/condition/renal-impairment
Target name:
Severe Renal Impairment / Dialysis
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
The kidneys are responsible for clearing L-Carnitine and its metabolites. In severe kidney disease, these substances can accumulate to potentially toxic levels.
Actionable advice:
L-Carnitine should not be taken with severe kidney disease, except under the direct supervision of a nephrologist.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Carnitine homeostasis is maintained by absorption from diet, a modest rate of synthesis, and efficient renal reabsorption.
Label source:
PubMed: Annals of the New York Academy of Sciences (2004)
Source url:
Exact phrase from label:
Kidney function estimates as a covariate on the elimination rate constant (k) reliably improved model fit.
Label source:
PubMed: Pharmacotherapy (2023)
Source url:
Exact phrase from label:
However, concerns about the possible deleterious consequences of such a dosage regimen still remain given that plasma concentrations of trimethylamine-N-oxide were continually rising and approximately doubled in a two-week period.
Label source:
PubMed: Current drug metabolism (2006)
Action type:
avoid
Target id:
/class/antibiotics-long-term
Target name:
Pivalate-Conjugated Antibiotics
Severity:
major
Interaction type:
requirement
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Certain antibiotics (e.g., pivampicillin) release pivalic acid, which binds to carnitine and is excreted, causing a rapid and severe depletion of the body's carnitine stores.
Actionable advice:
Long-term pivalate-conjugated antibiotics deplete carnitine. If you're on one, ask your physician about L-carnitine supplementation to prevent deficiency.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Formation and urinary excretion of pivaloylcarnitine generated from pivaloyl-CoA is the major route of pivalate elimination. Because the total body carnitine pool is limited and can only slowly be replenished through normal diet or biosynthesis, treatment with large doses of pivalate prodrugs may deplete tissue carnitine content.
Label source:
PubMed: Pharmacological reviews (2002)
Source url:
Exact phrase from label:
This pivalic acid is carnitine-conjugated and excreted into urine. Carnitine acts as a carrier of long chain fatty acid to mitochondria and to beta-oxidation, thus an important molecule for energy production by beta-oxidation and maintenance of mitochondrial function. Because of this, long term administration of such antibiotics could induce depletion of carnitine from the body and lead to low ketotic hypoglycemia, convulsion and consciousness disturbance.
Label source:
PubMed: The Journal of toxicological sciences (2009)
Source url:
Exact phrase from label:
In seven girls on long-term treatment with a mixture of pivampicillin and pivmecillinam the mean total serum carnitine concentration fell to 15% (7-27%) of pretreatment values. The acylcarnitine fraction was 11-57% of total carnitine, compared with less than 2% before treatment.
Label source:
PubMed: Lancet (London, England) (1989)
Action type:
informational_none
Target id:
/dietary/tmao-precursor-foods
Target name:
High-Choline Foods & Red Meat
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Gut bacteria can convert L-Carnitine and choline (high in red meat, eggs) into TMA, which the liver converts to TMAO. High TMAO is a biomarker associated with increased cardiovascular risk.
Actionable advice:
Consider monitoring TMAO levels if taking L-Carnitine, especially with a diet high in red meat and eggs.
Validation status:
validated_via_class_inference
Evidence tier:
tier_c
Evidence basis:
class_inference_summary
Evidence anchors:
Source url:
Established mechanism / class pharmacology (no single primary source quoted)
Exact phrase from label:
Well-established (Koeth et al., Nat Med 2013): gut microbiota convert dietary L-carnitine (abundant in red meat) to TMA, which the liver oxidizes to TMAO, a metabolite associated with cardiovascular risk. FLAG: the cited DOI (10.1016/j.cmet.2011.02.018) is actually a butyrate/colonocyte paper (Donohoe 2011), NOT the carnitine-TMAO source - citation is misattributed; the mechanism is sound (correct cite: Koeth 2013).
Label source:
Class inference
Action type:
monitor
Target id:
/class/anticonvulsants
Target name:
Certain Anticonvulsants (e.g., Valproic Acid)
Severity:
moderate
Interaction type:
requirement
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Long-term use of certain anticonvulsants like valproic acid, phenobarbital, phenytoin, and carbamazepine can deplete carnitine stores, leading to a secondary deficiency.
Actionable advice:
It is important to talk to a doctor about carnitine level testing and potential supplementation when taking these anticonvulsants long-term.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
The panelists agreed that intravenous L-carnitine supplementation is clearly indicated for valproate (VPA)-induced hepatotoxicity, overdose, and other acute metabolic crises associated with carnitine deficiency.
Label source:
PubMed: L-carnitine supplementation in childhood epilepsy: current perspectives. (PMID 9821988)
Action type:
informational_none
Target id:
/condition/pregnancy
Target name:
Pregnancy
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
The safety of L-Carnitine supplementation during pregnancy has not been well-established. It should only be used if a deficiency is diagnosed and prescribed by a physician.
Actionable advice:
L-Carnitine supplementation is best avoided during pregnancy unless medically advised.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
There isn't enough reliable information to know if L-carnitine is safe to use when pregnant.
Label source:
Anecdotal: WebMD
Action type:
avoid
Target id:
/condition/lactation
Target name:
Breastfeeding (Lactation)
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
It is not known if supplemental L-Carnitine passes into breast milk in significant amounts or its effect on an infant. Avoid use unless medically advised.
Actionable advice:
L-Carnitine supplementation is best avoided while breastfeeding unless medically advised.
Validation status:
anecdotal
Evidence tier:
tier_d
Evidence basis:
anecdotal_summary
Evidence anchors:
Exact phrase from label:
It is not known if acetyl-L-carnitine passes into breast milk, but carnitine passes into breast milk.
Label source:
Anecdotal: WebMD
Action type:
avoid
Target id:
/biomarker/tmao
Target name:
Trimethylamine N-oxide (TMAO)
Severity:
moderate
Interaction type:
assay_interference
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
L-Carnitine supplementation is a direct precursor to TMAO production by the gut microbiome and can significantly elevate its levels in the blood, impacting test results.
Actionable advice:
Disclose L-Carnitine use to your physician when interpreting TMAO lab results for cardiovascular risk assessment.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
One of the major concerns is that the intestinal metabolism of L-carnitine generates trimethylamine-N-oxide (TMAO), a compound that has been linked with faster atherosclerosis progression.
Label source:
PubMed: Role of L-carnitine in Cardiovascular Health: Literature Review. (PMID 39329040)
Action type:
monitor
Target id:
/intervention/exercise
Target name:
Exercise
Severity:
minor
Interaction type:
synergistic
Nature:
temporal
Temporal spacing:
Hours before target:
1
Hours after target:
null
Description:
L-Carnitine facilitates the transport of fatty acids into mitochondria for energy production, a process that is crucial during physical activity. Taking it before exercise may support fat metabolism.
Actionable advice:
For potential exercise benefits, L-Carnitine is best taken about 30-60 minutes before a workout.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Given its pivotal role in fatty acid oxidation and energy metabolism, l-carnitine has been investigated as ergogenic aid for enhancing exercise capacity in the healthy athletic population.
Label source:
PubMed: l-Carnitine Supplementation in Recovery after Exercise. (PMID 29534031)
Action type:
separate
Target id:
/dietary/meal
Target name:
Any Meal
Severity:
minor
Interaction type:
requirement
Nature:
temporal
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Taking L-Carnitine with a meal, particularly one containing some fats, may improve its absorption and align its availability with the metabolic processes it supports.
Actionable advice:
L-Carnitine is generally best taken with a meal to enhance absorption and minimize potential gastrointestinal upset.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Although inflammatory arthritis has not been previously associated with CPT2 deficiency, existing literature suggests a potential mechanism involving synovial inflammation secondary to the accumulation of fatty acids and acylcarnitine. Attacks are most commonly triggered by infections, strenuous exercise, fasting and consumption of a fat-rich meal.
Label source:
PubMed: Migratory and intermittent polyarthritis as an atypical presentation of carnitine palmitoyltransferase II deficiency with positive response to treatment with Interleukin-1 receptor antagonist: a case presentation and case-based review. (PMID 40580346)
Action type:
informational_none
Target id:
/intervention/coenzyme-q10
Target name:
Coenzyme Q10 (CoQ10)
Severity:
minor
Interaction type:
synergistic
Nature:
temporal
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Both L-Carnitine and CoQ10 are essential for mitochondrial energy production. Taking them together provides complementary support for cellular energy pathways.
Actionable advice:
Consider taking L-Carnitine and CoQ10 at the same time with a meal.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Bioenergetic support with L-carnitine, NAD+ precursors, coenzyme Q10, deoxyarbutin, and melatonin restored ATP levels and stabilized ΔΨm, while ΔΨm preservation and mPTP modulation by irisin, cyclosporine/NIM811, and TRO40303 limited necrosis.
Label source:
PubMed: Beyond Supportive Care: Mitochondria as a Strategic Therapeutic Avenue in Acute Pancreatitis. (PMID 41854947)
Action type:
informational_none
Target id:
/intervention/acetyl-l-carnitine
Target name:
Acetyl-L-Carnitine (ALCAR)
Severity:
minor
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
L-Carnitine and ALCAR are related compounds that may compete for the same transporters for absorption in the gut, potentially reducing the uptake of both if taken simultaneously.
Actionable advice:
If taking both forms of carnitine for different purposes, separate the doses by at least 2 hours.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
In vitro experiments suggest that acetyl-L-carnitine is partially hydrolyzed in enterocytes during absorption. In vivo, circulating acetyl-L-carnitine concentration was increased 43% after oral acetyl-L-carnitine supplements of 2 g/day, indicating that acetyl-L-carnitine is absorbed at least partially without hydrolysis.
Label source:
PubMed: Annals of the New York Academy of Sciences (2004)
Source url:
Exact phrase from label:
The uptake of both isomers was a saturable process and high concentrations of D-carnitine, acetyl-L-carnitine and trimethylaminobutyrate inhibited L-carnitine uptake.
Label source:
PubMed: Biochimica et biophysica acta (1984)
Source url:
Exact phrase from label:
Carnitine transport by guinea-pig enterocytes demonstrate characteristics of a carrier-mediated process since it was inhibited by D-carnitine and trimethylaminobutyrate, as well as being temperature and concentration dependent.
Label source:
PubMed: Biochimica et biophysica acta (1986)
Action type:
separate