Safety Profile
Known Safety Concerns
- Mild anticoagulant effect -- caution with warfarin
- Thyroid stimulation at very high doses
- Nausea and restlessness at high doses
- Bipolar disorder caution -- may trigger mania in predisposed individuals
Contraindications
- Mild anticoagulant effect -- caution with warfarin
- Thyroid stimulation at very high doses
Interactions
Information not yet available for this ingredient profile.
Evidence and Scientific Findings
Ingredient Overview
Acetyl-L-carnitine is the acetylated form of L-carnitine that crosses the blood-brain barrier. Used for cognitive support, neuropathy, and energy. Well tolerated at standard doses. May have mild anticoagulant effects and interact with warfarin. Thyroid stimulating effects have been reported at very high doses.
Biological and Chemical Classification
- Scientific Name
- Acetyl-L-carnitine (ALCAR)
Mechanism of Action
Information not yet available for this ingredient profile.
Clinical Evidence of Effectiveness
Information not yet available for this ingredient profile.
Pharmacokinetics
Information not yet available for this ingredient profile.
Recommended Dosage
Information not yet available for this ingredient profile.
SETI — Scientific Evidence Transparency Index
Executive Summary — Ingredient Assessment
- 10 studies reviewed
- 0 high-quality studies (meta-analysis or RCT)
- Main clinical benefit observed: Metabolic
- Evidence consistency: High consistency across studies (100%)
- Mild anticoagulant effect -- caution with warfarin
- Thyroid stimulation at very high doses
- Nausea and restlessness at high doses
- Bipolar disorder caution -- may trigger mania in predisposed individuals
The available scientific evidence for Acetyl-L-Carnitine indicates notable safety signals that warrant caution. Use should be considered carefully and monitored, particularly in sensitive populations or alongside other medications.
Total SETI Score
High risk| Evidence quality | 10/40 |
| Evidence consistency | 20/20 |
| Safety signals | 0/20 |
| Study recency | 10/10 |
| Evidence transparency | 10/10 |
Evidence Summary
- 10 studies reviewed
- 0 high-quality studies (meta-analysis or systematic review)
- 0 studies identified benefits or no safety concern (GREEN)
- 10 studies reported limited or advisory safety evidence (YELLOW)
Evidence Policy
Only peer-reviewed scientific literature indexed in PubMed or comparable databases is included in this evaluation. Commercial websites, blogs, and marketing materials are excluded. All references include direct traceable links to source documents.
Last updated: 25 მარ 2026, 12:48
Evidence Distribution
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Observational / other LOW evidence YELLOWAssociation between the gut microbiome and plasma metabolites linked to vocalization-based temperament in Merino sheep. ↗Ding L et al.. Association between the gut microbiome and plasma metabolites linked to vocalization-based temperament in Merino sheep.. Microbiome. 2026. PMID:41715225.PMID 41715225 ↗Journal MicrobiomeYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41715225/
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Observational / other LOW evidence YELLOWElevated serum trimethylamine N-oxide (TMAO) and trimethyllysine in patients with amyotrophic lateral sclerosis (ALS): An exploratory case-control study. ↗Sotgia S et al.. Elevated serum trimethylamine N-oxide (TMAO) and trimethyllysine in patients with amyotrophic lateral sclerosis (ALS): An exploratory case-control study.. IBRO Neurosci Rep. 2026. PMID:41705073.PMID 41705073 ↗Journal IBRO Neurosci RepYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41705073/
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Observational / other LOW evidence YELLOWAcetyl-carnitine improves hyperactivity and learning deficits in KAT6A haploinsufficient mice. ↗Eccles S et al.. Acetyl-carnitine improves hyperactivity and learning deficits in KAT6A haploinsufficient mice.. Life Sci Alliance. 2026. PMID:41702672.PMID 41702672 ↗Journal Life Sci AllianceYear 2026Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/41702672/
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Observational / other LOW evidence YELLOWLongitudinal Brain Structural, Neurochemical, and Behavioral Changes Following Traumatic Brain Injury in Immature Rat Brain with ALCAR Treatment. ↗Scafidi S et al.. Longitudinal Brain Structural, Neurochemical, and Behavioral Changes Following Traumatic Brain Injury in Immature Rat Brain with ALCAR Treatment.. Neurochem Res. 2025. PMID:40736608.PMID 40736608 ↗Journal Neurochem ResYear 2025Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/40736608/
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Observational / other LOW evidence YELLOWAcetyl L-Carnitine Protects Zebrafish Embryos From Verapamil and Inorganic Arsenic-Induced Cardiotoxicity and Developmental Toxicity With No Effect on Supernumerary Motor Neuron Development. ↗Twaddle NC et al.. Acetyl L-Carnitine Protects Zebrafish Embryos From Verapamil and Inorganic Arsenic-Induced Cardiotoxicity and Developmental Toxicity With No Effect on Supernumerary Motor Neuron Development.. J Appl Toxicol. 2025. PMID:40234040.PMID 40234040 ↗Journal J Appl ToxicolYear 2025Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/40234040/
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Observational / other LOW evidence YELLOWAcetyl-l-carnitine alleviates valproate-induced autism-like behaviors through attenuation of hippocampal mitochondrial dysregulation. ↗Zahedi E et al.. Acetyl-l-carnitine alleviates valproate-induced autism-like behaviors through attenuation of hippocampal mitochondrial dysregulation.. Neuroscience. 2024. PMID:39168175.PMID 39168175 ↗Journal NeuroscienceYear 2024Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/39168175/
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Observational / other LOW evidence YELLOWInvestigation of the effect of carnitine on cerebral vasospasm in experimental subarachnoid hemorrhage model. ↗Resitoglu G et al.. Investigation of the effect of carnitine on cerebral vasospasm in experimental subarachnoid hemorrhage model.. Sci Rep. 2023. PMID:38155210.PMID 38155210 ↗Journal Sci RepYear 2023Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/38155210/
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Observational / other LOW evidence YELLOWEffects of Acetyl-L-Carnitine on Oxidative Stress in Amyotrophic Lateral Sclerosis Patients: Evaluation on Plasma Markers and Members of the Neurovascular Unit. ↗Grossini E et al.. Effects of Acetyl-L-Carnitine on Oxidative Stress in Amyotrophic Lateral Sclerosis Patients: Evaluation on Plasma Markers and Members of the Neurovascular Unit.. Antioxidants (Basel). 2023. PMID:37891966.PMID 37891966 ↗Journal Antioxidants (Basel)Year 2023Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/37891966/
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Observational / other LOW evidence YELLOWAnti-Hyperalgesic Efficacy of Acetyl L-Carnitine (ALCAR) Against Visceral Pain Induced by Colitis: Involvement of Glia in the Enteric and Central Nervous System. ↗Lucarini E et al.. Anti-Hyperalgesic Efficacy of Acetyl L-Carnitine (ALCAR) Against Visceral Pain Induced by Colitis: Involvement of Glia in the Enteric and Central Nervous System.. Int J Mol Sci. 2023. PMID:37834289.PMID 37834289 ↗Journal Int J Mol SciYear 2023Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/37834289/
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Observational / other LOW evidence YELLOWHyperpolarized [1-(13)C]Acetyl-l-Carnitine Probes Tricarboxylic Acid Cycle Activity In Vivo. ↗Chen J et al.. Hyperpolarized [1-(13)C]Acetyl-l-Carnitine Probes Tricarboxylic Acid Cycle Activity In Vivo.. ACS Sens. 2023. PMID:37578472.PMID 37578472 ↗Journal ACS SensYear 2023Study type Observational / otherEvidence strength LOW evidencePubMed link https://pubmed.ncbi.nlm.nih.gov/37578472/
Score Transparency
0 of 10 approved references (score saturates at 10). More peer-reviewed studies = stronger evidence base.
Method: Q = number of approved references ÷ 10 (capped at 1.0)
Limited — mostly case reports or animal studies
Method: L = mean study-level weight across approved references. Level 1 (meta-analysis / systematic review) = 1.0; Level 2 (RCT) = 0.8; Level 3 (cohort/case-control) = 0.6; Level 4 (case report) = 0.4; Level 5 (animal / in-vitro) = 0.2.
Mixed or neutral — roughly equal benefit and risk signals
Method: D = (sum of risk-scored references − sum of benefit-scored references) ÷ total evidence score, then scaled from [−1, 1] to [0, 1]. 0.0 = pure benefit; 0.5 = neutral; 1.0 = pure risk.
One or more monitoring-level safety signals active
Method: S = 0.5 (neutral baseline) + sum of active signal severity deltas ÷ 10. Severity deltas: Critical = +2.0, High = +1.5, Moderate = +1.0, Low = +0.5. Capped at 1.0.
Final GIRI Score for Acetyl-L-Carnitine. Risk level thresholds: Low 0–3.0 · Moderate 3.0–5.5 · High 5.5–7.5 · Critical 7.5–10.
Full methodology & data sources
The GIRI Score is computed entirely from structured data — no editorial scoring or subjective weighting is applied at any step.
- References: Only approved references are counted. Each reference is assigned an evidence level (L1–L5) and a direction (risk / neutral / benefit) by the reference manager or AI classifier.
- Safety Signals: Sourced from regulatory agencies (FDA, EMA, Health Canada, TGA, and others) and pharmacovigilance databases. Only active signals count toward the score.
- Formula version: GIRI Score v3.7.0 — Q × L × D × S × 10.
- Limitations: The score reflects published evidence and recorded signals as of the last update date. It is not a clinical risk assessment and should not replace advice from a qualified healthcare professional.
Risk Level Classification
Based on available regulatory signals and scientific evidence, this ingredient presents a low safety concern under normal conditions of use.
0–3.0
3.0–5.5
5.5–7.5
7.5–10
The score pin shows exactly where this ingredient falls on the fixed risk scale.
What drove the Low classification for Acetyl-L-Carnitine
A score of 3.5 places this ingredient in the Low band. Thresholds: Low 0–3.0 · Moderate 3.0–5.5 · High 5.5–7.5 · Critical 7.5–10.
0 approved references.
Limited — mostly case reports or animal studies (Level 4–5).
Neutral or mixed — benefit and risk signals roughly balanced.
No active signals — S component is at neutral baseline (0.5), contributing no extra risk weight.
No major regulatory restrictions or advisories recorded across monitored jurisdictions (FDA, EMA, Health Canada, TGA, and others).
How are the Low / Moderate / High / Critical thresholds defined?
The four risk levels are fixed score bands. A score is assigned to exactly one level based on where it falls:
| Level | Score | Meaning |
|---|---|---|
| LOW | 0.0 – 2.9 | Sparse or predominantly beneficial evidence. No active safety alerts. |
| MODERATE | 3.0 – 5.4 | Mixed signals — some risk alongside benefit. Caution at high doses or in sensitive groups. |
| HIGH | 5.5 – 7.4 | Multiple studies or regulatory alerts documenting adverse effects. Professional oversight recommended. |
| CRITICAL | 7.5 – 10 | Regulatory restrictions in one or more major jurisdictions. Serious documented harm. Avoid without specialist supervision. |
Thresholds are fixed constants (GIRI_Score_Utils::LEVEL_THRESHOLDS). They do not change per ingredient and are never subject to editorial adjustment.