A systematic review of L-carnitine (LC) in the treatment of psychiatric and neurological disorders was conducted, analyzing 60 relevant articles published up to November 2023. LC, an essential amino acid, plays a role in energy metabolism and has been studied for its neuroprotective effects. The review found that LC showed therapeutic benefits in conditions such as hepatic encephalopathy (HE), Alzheimer's disease (AD), carpal tunnel syndrome (CTS), cognitive dysfunction (CD), migraine, neurofibromatosis (NF), peripheral nervous system diseases (PNSDs), Raynaud's syndrome (RS), and stroke. However, its efficacy was limited in conditions like amyotrophic lateral sclerosis (ALS), ataxia, attention deficit hyperactivity disorder (ADHD), depression, chronic fatigue syndrome (CFS), Down syndrome (DS), and sciatica. LC was found to improve outcomes in HE, AD, CTS, CD, migraine, NF, PNSDs, RS, and stroke, with some studies showing significant improvements in neurological and psychiatric symptoms. However, the evidence for ALS, ataxia, ADHD, depression, CFS, DS, and sciatica was less consistent. The review also noted that LC had a low incidence of adverse effects (AEs), with common AEs including gastrointestinal issues, headache, and nausea. The mechanisms of LC's action include reducing oxidative stress, modulating inflammatory mediators, improving mitochondrial function, and enhancing cholinergic neurotransmission. The review concluded that LC has potential as a therapeutic agent for various neurological and psychiatric disorders, but further research is needed to confirm its efficacy and safety, particularly in conditions where the evidence was limited. The findings suggest that LC could be beneficial for patients with certain neurological and psychiatric conditions, but its use should be guided by the available evidence and individual patient factors.A systematic review of L-carnitine (LC) in the treatment of psychiatric and neurological disorders was conducted, analyzing 60 relevant articles published up to November 2023. LC, an essential amino acid, plays a role in energy metabolism and has been studied for its neuroprotective effects. The review found that LC showed therapeutic benefits in conditions such as hepatic encephalopathy (HE), Alzheimer's disease (AD), carpal tunnel syndrome (CTS), cognitive dysfunction (CD), migraine, neurofibromatosis (NF), peripheral nervous system diseases (PNSDs), Raynaud's syndrome (RS), and stroke. However, its efficacy was limited in conditions like amyotrophic lateral sclerosis (ALS), ataxia, attention deficit hyperactivity disorder (ADHD), depression, chronic fatigue syndrome (CFS), Down syndrome (DS), and sciatica. LC was found to improve outcomes in HE, AD, CTS, CD, migraine, NF, PNSDs, RS, and stroke, with some studies showing significant improvements in neurological and psychiatric symptoms. However, the evidence for ALS, ataxia, ADHD, depression, CFS, DS, and sciatica was less consistent. The review also noted that LC had a low incidence of adverse effects (AEs), with common AEs including gastrointestinal issues, headache, and nausea. The mechanisms of LC's action include reducing oxidative stress, modulating inflammatory mediators, improving mitochondrial function, and enhancing cholinergic neurotransmission. The review concluded that LC has potential as a therapeutic agent for various neurological and psychiatric disorders, but further research is needed to confirm its efficacy and safety, particularly in conditions where the evidence was limited. The findings suggest that LC could be beneficial for patients with certain neurological and psychiatric conditions, but its use should be guided by the available evidence and individual patient factors.