Acetylated ester of L-carnitine; supplement with claimed neurotropic effect
ATC code: A16AA-ALCAR (Acetyl-L-carnitine (local code))
Brand names – supplements
Acetyl-L-Carnitine, Carnitene Acetile
Supplements are not tested in clinical trials and are not registered as medications.
Acetylated L-carnitine crosses the blood-brain barrier more readily than carnitine itself. Cellular hydrolysis yields L-carnitine and an acetyl group. Acetyl feeds into acetyl-CoA and acetylcholine synthesis, the basis of the claimed nootropic effect. In mitochondria it acts in fatty-acid transport like L-carnitine. Oral bioavailability is 5–10% with a 4–6 hour half-life. In Spain and most EU countries it is registered as complemento alimenticio, not as a medicine.
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
In painful diabetic neuropathy, acetyl-L-carnitine has individual RCTs showing positive effects on pain and nerve fibre regeneration (Sima 2005, pooled analysis of two RCTs with 1257 patients). These data did not enter or Spanish SED guidelines as standard: first line is gabapentinoids, duloxetine, tricyclics. A clinician may consider acetyl-L-carnitine as optional support, never as a replacement for evidence-based neuropathic pain therapy.
Not recommended
Acetyl-L-carnitine is marketed as a nootropic that slows dementia and improves memory in Alzheimer disease. The Cochrane review (Hudson & Tabet 2003, updated 2014) analysed 16 RCTs with 1204 patients: differences from placebo on clinical scales (MMSE, ADAS-cog) are minimal and do not reach clinical significance. The product is not in , or Spanish SEN guidelines for Alzheimer disease. Standard therapy – cholinesterase inhibitors (donepezil, rivastigmine, galantamine) and memantine – is not replaced by acetyl-L-carnitine.
Not recommended
Biohackers market acetyl-L-carnitine for anti-ageing and mitochondrial support. The claim rests on early-2000s Bruce Ames rat studies where ALCAR plus alpha-lipoic acid improved mitochondrial function in old animals. Human translation is not confirmed. No human RCTs with lifespan endpoints exist. rejected the health claim «contribute to the maintenance of cognitive function in elderly». Evidence-based risk reduction for ageing comes from blood pressure, lipid and glucose control, physical activity and not smoking, not from supplements.
Not recommended
Acetyl-L-carnitine is marketed to healthy adults as a memory, focus and cognitive support supplement. Data in healthy volunteers are inconsistent: small RCTs, short duration, heterogeneous endpoints, effects within scale noise. has not approved any cognitive health claim for acetyl-L-carnitine. NIH ODS rates cognitive effects as insufficient evidence. Genuine memory complaints require workup (B12, TSH, depression and sleep screening, neurocognitive testing if indicated), not a supplement.
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FDA Category C. Data on acetyl-L-carnitine in pregnancy are limited. AEMPS does not endorse use of complementos alimenticios without a therapeutic indication during gestation. There is no rationale for use in healthy pregnant women.
Breast milk excretion data are absent. eLactancia rates acetyl-L-carnitine as «possible risk». There is no rationale for use as a complemento alimenticio in healthy mothers.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Acetyl-L-carnitine is evaluated for the following indications with varying evidence strength: Diabetic polyneuropathy (evidence tier C), Alzheimer disease (evidence tier D), Memory and concentration enhancement (evidence tier D). See the full indication matrix with dosing and citations above on this page.
Common side effects of Acetyl-L-carnitine (≥ 1 in 100): Nausea, Abdominal pain, Agitation and insomnia, Fishy body odour (as with L-carnitine). See the Safety section for uncommon and serious reactions.
FDA category C. FDA Category C. Data on acetyl-L-carnitine in pregnancy are limited. AEMPS does not endorse use of complementos alimenticios without a therapeutic indication during gestation. There is no rationale for use in healthy pregnant women.
Breast milk excretion data are absent. eLactancia rates acetyl-L-carnitine as «possible risk». There is no rationale for use as a complemento alimenticio in healthy mothers.
Acetyl-L-carnitine is contraindicated in: Hypersensitivity to acetyl-L-carnitine; Epilepsy (risk of lowering seizure threshold); Prior bipolar disorder (mania induction reported). Full list in the Safety section.