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Alpha-lipoic acid
A sulfur-containing compound that the body makes and foods hold in tiny amounts, widely used for nerve damage from diabetes and studied for blood sugar.
Explained simply · Last reviewed
What it is
Alpha-lipoic acid is a sulfur-containing compound that the body makes for itself and that foods contain in very small amounts. LiverTox, the US government reference on drug-induced liver injury, describes it as a naturally occurring fatty acid that several enzymes need in order to work, including enzymes in mitochondria that play a critical role in energy metabolism. It says adequate amounts are made in mitochondria. EFSA, the EU food safety agency, says it is mostly bound to protein in food, and that the richest natural sources are spinach among vegetables and kidney among meats. It is also called thioctic acid.
More about Alpha-lipoic acid
LiverTox, the US government reference on drug-induced liver injury, describes it as a naturally occurring fatty acid that several enzymes need in order to work, including enzymes in mitochondria that play a critical role in energy metabolism. It says adequate amounts are made in mitochondria. EFSA, the EU food safety agency, says it is mostly bound to protein in food, and that the richest natural sources are spinach among vegetables and kidney among meats. It is also called thioctic acid.
According to LiverTox, alpha-lipoic acid is a common ingredient in multivitamins and dietary supplements, and is purported to have antioxidant, antidiabetic and anti-aging effects. LiverTox notes that the FDA has not approved it as a treatment for any disease or condition. A 2004 Cochrane review says it was at first thought to be a vitamin, until it was found that humans and other animals make it.
A 2024 Cochrane review says alpha-lipoic acid is widely used for nerve damage caused by diabetes, but that there is no consensus about its benefits and harms, and that trials have given it into a vein or by mouth. The reviews below also studied it for blood sugar, weight, blood pressure, burning mouth syndrome, male fertility and dementia.
Also known as: ALA, lipoic acid, thioctic acid
At a glance
Safety: known risks, 1 group who should avoid it or take extra care and 1 documented interaction. See Safety ↓Claims made about Alpha-lipoic acid, and how strong the evidence is for each:
- Eases symptoms of nerve damage from diabetes (diabetic peripheral neuropathy) when taken for six months or longerEvidence rating: Evidence against
- Lowers blood sugar (HbA1c and fasting glucose) in people with type 2 diabetesEvidence rating: Limited
- Helps with weight lossEvidence rating: Limited
- Lowers blood pressureEvidence rating: Limited
- Eases burning mouth syndromeEvidence rating: Limited
- Improves sperm quality or the chance of pregnancy in men with infertilityEvidence rating: Limited
- Improves symptoms of dementiaEvidence rating: Insufficient
Each rating follows our published rules and the sources cited for it. We don’t add our own medical judgment. How we rate
Safety
Read this before the ratings below.
Risks
- LiverTox, the US government reference on drug-induced liver injury, says alpha-lipoic acid is usually well tolerated, but that side effects at higher doses can include abdominal discomfort, heartburn, constipation or diarrhea, nausea, dizziness and headache.
- LiverTox says rare, potentially severe effects have been reported after single large overdoses, including confusion, stupor, seizures, lactic acidosis, muscle breakdown (rhabdomyolysis), coma and multiorgan failure that can be fatal. The cases it describes include two toddlers who had seizures after swallowing alpha-lipoic acid tablets meant for someone else in the home.
- LiverTox says that despite widespread use, there have been no published reports of liver injury attributable to alpha-lipoic acid at conventional doses. It rates it an unlikely cause of clinically apparent liver injury.
- LiverTox notes that in a four-year trial of 460 people with diabetic nerve damage, severe adverse events were more frequent with alpha-lipoic acid than with placebo, 38% against 28%.
- A 2024 Cochrane review of three long-term trials in diabetic nerve damage found probably little or no difference from placebo in side effects that led people to stop treatment, at moderate certainty. None of the trials recorded all side effects or serious ones.
- A 2020 review of 71 placebo-controlled trials found no statistically significant increase in any type of side effect it examined, and its authors conclude the data support the safety of alpha-lipoic acid. Its estimates for stomach and gut side effects and for hospital admission leaned toward more events with alpha-lipoic acid, but the differences were not statistically significant.
- The same 2020 review notes concern raised by reports linking alpha-lipoic acid to insulin autoimmune syndrome (Hirata’s disease). It says alpha-lipoic acid might lead to antibodies to insulin and to low blood sugar in predisposed people, though the evidence is inconclusive.
Who should avoid it or take extra care
- People taking diabetes medicines or insulin: the 2020 safety review says the effect of alpha-lipoic acid on blood sugar “may require the adjustment of antidiabetic agents and insulin doses in patients taking antidiabetic drugs”.
Documented interactions
- Diabetes medicines, including insulin: A 2020 safety review says the effect of alpha-lipoic acid on blood sugar “may require the adjustment of antidiabetic agents and insulin doses in patients taking antidiabetic drugs”. Source [1]
Safety sources: Source [1]Source [2]Source [3]
What the evidence says
Each claim is rated on its own evidence. Ratings follow the scale on our methodology page.
Eases symptoms of nerve damage from diabetes (diabetic peripheral neuropathy) when taken for six months or longer Evidence rating: Evidence against
People with diabetes and burning or tingling feet take it hoping it will calm the nerve pain.
A 2024 Cochrane review found it probably makes little or no difference to symptoms after six months or two years, at moderate certainty; a 2023 review that also pooled shorter trials disagrees.
This claim is about long-term use. A 2024 Cochrane review searched for placebo-controlled trials lasting at least six months in adults with nerve damage from diabetes. It found three, with 816 adults analyzed in all. In two, alpha-lipoic acid or placebo was first given into a vein and then as tablets; the third used tablets alone. The reviewers report that drug companies sponsored all three.
Each symptom result comes from one trial. In 330 people given it into a vein and then as tablets, alpha-lipoic acid probably made little or no difference to symptoms after six months, compared with placebo. In 421 people taking tablets, it probably made little or no difference after two years. The reviewers rate how sure they are (certainty) moderate for both.
The Cochrane reviewers found it may make little or no difference to measured nerve impairment at six months, at low certainty, though they say a benefit cannot be ruled out. At two years it probably makes little or no difference, at moderate certainty. No trial measured quality of life, foot ulcers or amputations. All three trials lost many participants before the end, which lowered the certainty.
Other reviews reached different conclusions. The Cochrane reviewers describe two earlier reviews of short courses given into a vein, in one of them together with other treatments, that concluded alpha-lipoic acid improved symptoms. A 2023 review pooled ten trials of tablets, lasting from three weeks to two years. It found better symptom scores and some measures of nerve damage, but not pain on a visual scale, vibration sense or nerve conduction. Its authors say the symptom result is of low reliability because only six trials reported it and results varied.
The Cochrane reviewers set aside one trial the 2023 review included, because its results matched an earlier conference report and its authors would not share their data. LiverTox, the US government reference on drug-induced liver injury, says that in placebo-controlled trials alpha-lipoic acid was associated with mild improvements in surrogate markers of nerve damage “but was not shown to ameliorate symptoms or progression of neuropathy”. The reviews disagree, so this page takes the lower reading and rates the long-term claim evidence against, on the Cochrane review's moderate certainty.
Sources: Source [1]Source [2]Source [3]
Lowers blood sugar (HbA1c and fasting glucose) in people with type 2 diabetes Evidence rating: Limited
People with type 2 diabetes take it hoping it will bring their blood sugar down.
A 2022 review found slightly lower HbA1c and fasting glucose with tablets, at moderate and low certainty, but judged every change too small to matter to patients.
This claim is about laboratory measures of blood sugar, HbA1c and fasting glucose, in type 2 diabetes. A 2022 review pooled 16 randomized trials of alpha-lipoic acid tablets in 1,035 adults with type 2 diabetes, lasting from four weeks to a year. It analyzed how results changed as the daily amount rose. HbA1c and fasting glucose were lower as the amount went up. The reviewers rated how sure they are (certainty) moderate for HbA1c and low for fasting glucose.
Before analyzing, the reviewers set the smallest change that would matter to patients, and every effect they found was smaller. They conclude that the effects “were not clinically important” and that their findings do not support its use in clinical practice for type 2 diabetes. They add that this lack of clinical importance does not disprove its benefits. Results varied widely between trials, and the HbA1c result lost significance when any one of three trials was left out. The review's reference list gives the title of one trial in both the HbA1c and fasting glucose analyses as a study of 5-aminolevulinic acid phosphate with sodium ferrous citrate.
A 2025 review of 11 trials in overweight or obese adults, most without other conditions, found no significant change in fasting glucose or insulin resistance. EFSA, the EU food safety agency, assessed a claim in 2011 that alpha-lipoic acid increases insulin sensitivity in the general population. It was given no studies it could draw conclusions from, and concluded that a cause and effect relationship had not been established.
This page rates the claim on the lowest certainty the 2022 review gives these outcomes, low.
Sources: Source [1]Source [2]Source [3]
Helps with weight loss Evidence rating: Limited
People take it hoping it will help them lose weight.
A 2017 review found about 1.3 kg more weight lost than with placebo; a 2022 review in type 2 diabetes judged the weight changes too small to matter, at moderate to low certainty.
A 2017 review pooled randomized placebo-controlled trials lasting 8 to 52 weeks, with 534 people on alpha-lipoic acid and 413 on placebo. Only three trials were designed to help overweight or obese people lose weight. The rest studied people with diabetes, metabolic syndrome, rheumatoid arthritis and other conditions. People taking alpha-lipoic acid lost on average 1.27 kg more than those on placebo, and results varied widely between trials.
The 2017 reviewers describe the loss as small and short-term, and say further research is needed on its long-term benefits. They did not grade certainty.
A 2022 review of trials in adults with type 2 diabetes found lower body weight and body mass index as the daily amount rose. It rated certainty moderate for body weight and low for body mass index. It judged both changes smaller than the smallest difference that matters to patients. The body weight result depended on one trial; without it, the change was no longer significant.
This page rates the claim on the lowest certainty for these outcomes, low.
Sources: Source [1]Source [2]
Lowers blood pressure Evidence rating: Limited
People with high blood pressure take it hoping it will bring their readings down.
A 2023 review found lower blood pressure at moderate to high certainty, though most of its trials found no difference on their own; a 2022 review in type 2 diabetes found none for systolic pressure.
A 2023 review pooled 11 randomized trials with 674 adults, including people with type 2 diabetes, obesity, rheumatoid arthritis and other conditions. Systolic blood pressure was 5.46 mmHg lower with alpha-lipoic acid than in control groups, and diastolic pressure 3.36 mmHg lower. The reviewers rated how sure they are (certainty) moderate for systolic and high for diastolic pressure.
Results varied very widely between trials, and seven of the 11 trials reported no significant difference on their own. The reviewers found signs of publication bias for systolic pressure. They conclude that alpha-lipoic acid “could exert favorable effects” on blood pressure, but also write in their discussion that it “may not be very beneficial for reducing BP”.
A 2022 review of trials in adults with type 2 diabetes found no significant change in systolic pressure, at very low certainty. It found a small rise in diastolic pressure, at low certainty, which did not persist when two trials were left out.
The reviews disagree, so this page takes the lower reading and rates the claim on the 2022 review's very low certainty.
Sources: Source [1]Source [2]
Eases burning mouth syndrome Evidence rating: Limited
People with a burning feeling in the mouth that has no clear cause take it hoping for relief.
A 2022 review found no significant drop in pain scores, at low certainty, but more people reporting improvement than with placebo, at moderate certainty, from trials at high or unclear risk of bias.
A 2022 review describes burning mouth syndrome as a long-lasting burning feeling inside the mouth without any known dental or medical cause. It gathered nine randomized trials of alpha-lipoic acid with 594 people, all at university clinics in Brazil, Italy, Spain, Argentina and Turkey. The reviewers judged every trial they assessed at high or unclear risk of bias.
In three trials that compared alpha-lipoic acid with placebo on a pain scale, pain did not differ significantly, at low certainty. In five trials, people taking alpha-lipoic acid were about 1.9 times as likely as those on placebo to report that their symptoms had improved, at moderate certainty.
The reviewers conclude that the evidence is of low quality and that larger studies are needed. This page rates the claim on the lowest certainty the review gives these outcomes, low.
Sources: Source [1]
Improves sperm quality or the chance of pregnancy in men with infertility Evidence rating: Limited
Men trying for a baby take it hoping it will improve their sperm and their chances of becoming a father.
A 2025 review of five small trials found better sperm movement and shape, rated high certainty, but no clear effect on pregnancy; its authors say the results might not be reliable.
A 2025 review pooled five randomized placebo-controlled trials in 250 men with infertility, each lasting about three months. Men taking alpha-lipoic acid had better sperm movement (motility) and fewer abnormally shaped sperm. Sperm concentration, semen volume and the share of live sperm did not change significantly.
Only two trials, with 85 men, reported pregnancies: 9 of 49 with alpha-lipoic acid and 3 of 36 with placebo. The difference was not statistically significant. The reviewers say this may reflect the small number of men and the short follow-up.
The reviewers rated how sure they are (certainty) high for every outcome. They also write that all the trials were small, that results for sperm movement varied widely, and that “the results might not be reliable or generalizable to larger populations”. Their conclusion says the review “suggests strong evidence” for alpha-lipoic acid, especially for sperm movement.
The reviewers' own caveats about small trials and unreliable results describe the evidence as weaker than their high certainty rating, so this page rates the claim limited, from five small trials of about three months.
Sources: Source [1]
Improves symptoms of dementia Evidence rating: Insufficient
Families of people with dementia, and people worried about memory loss, take it hoping it will slow the decline.
A Cochrane review, with a search run in January 2008, found no double-blind randomized placebo-controlled trials of alpha-lipoic acid alone, and could draw no conclusions about dementia.
A Cochrane review, first published in 2004 with its search last run in January 2008, looked for double-blind, randomized, placebo-controlled trials of alpha-lipoic acid in people with any form of dementia. It found none. It excluded two trials because alpha-lipoic acid was given together with other supplements, and one study in Alzheimer's disease because it was not randomized or placebo-controlled.
The reviewers write that it is not possible to comment on its use for any form of dementia, and that on the evidence available it “cannot be recommended for the treatment of dementia”. They say alpha-lipoic acid has shown promise in animal studies and that trials in people are needed. With no trials to assess, this page rates the claim insufficient.
Sources: Source [1]
Which form the evidence used
Supplements are sold in several forms. This is what the sources on this page say about them — which form the research used, and any comparison those sources themselves made. Where they made none, this page does not rank the forms.
Racemic alpha-lipoic acid (a mix of the R and S forms), What the sources supportDetails
EFSA, the EU food safety agency, says food supplements generally use the racemic form, a mix of the R and S forms. A 2025 review of trials in overweight or obese adults says most of its trials used racemic mixtures. Source [1]Source [2]
R-alpha-lipoic acid (R-ALA), Details
EFSA says the natural compound is the R form. Two trials in the 2023 blood pressure review cited below gave the R form, and that review did not report them separately. None of the claims on this page rests on the R form alone. Source [1]Source [2]
Sources
- Alpha-lipoic acid for diabetic peripheral neuropathyCochrane Database of Systematic Reviews, 2024 · Systematic review · Primary source · Certainty: low
- Effects of Oral Alpha-Lipoic Acid Treatment on Diabetic Polyneuropathy: A Meta-Analysis and Systematic ReviewNutrients, 2023 · Meta-analysis · Primary source
- Alpha Lipoic AcidLiverTox: Clinical and Research Information on Drug-Induced Liver Injury, National Institute of Diabetes and Digestive and Kidney Diseases, 2023 · Health authority summary · Primary source
- Efficacy and safety of oral alpha-lipoic acid supplementation for type 2 diabetes management: a systematic review and dose–response meta-analysis of randomized trialsEndocrine Connections, 2022 · Meta-analysis · Primary source · Certainty: very low
- Alpha-lipoic acid on intermediate disease markers in overweight or obese adults: a systematic review and meta-analysisBMJ Open, 2025 · Meta-analysis · Primary source
- Scientific Opinion on the substantiation of health claims related to alpha-lipoic acid and “protection of the nerve system” (ID 3157) and increase in insulin sensitivity (ID 3158) pursuant to Article 13(1) of Regulation (EC) No 1924/2006EFSA Panel on Dietetic Products, Nutrition and Allergies (EFSA Journal), 2011 · Health authority summary · Primary source
- Alpha-lipoic acid (ALA) as a supplementation for weight loss: results from a meta-analysis of randomized controlled trialsObesity Reviews, 2017 · Meta-analysis · Primary source
- The effects of alpha lipoic acid (ALA) supplementation on blood pressure in adults: a GRADE-assessed systematic review and dose-response meta-analysis of randomized controlled trialsFrontiers in Cardiovascular Medicine, 2023 · Meta-analysis · Primary source · Certainty: moderate
- Efficacy of alpha-lipoic acid in patients with burning mouth syndrome compared to that of placebo or other interventions: a systematic review with meta-analysesJournal of Dental Anesthesia and Pain Medicine, 2022 · Meta-analysis · Primary source · Certainty: low
- Efficacy of Alpha Lipoic Acid Supplementation in Sperm Parameters: A Systematic Review and Meta-Analysis of Randomized TrialsInternational Braz J Urol, 2025 · Meta-analysis · Primary source · Certainty: high
- Alpha lipoic acid for dementiaCochrane Database of Systematic Reviews, 2004 · Systematic review · Primary source
- Safety Evaluation of α-Lipoic Acid Supplementation: A Systematic Review and Meta-Analysis of Randomized Placebo-Controlled Clinical StudiesAntioxidants, 2020 · Meta-analysis · Primary source · Certainty: high
Page history
Show all 2 changes to this page
- — Published.
- — First drafted. Long-term use for diabetic nerve symptoms rated evidence against; blood sugar in type 2 diabetes, weight loss, blood pressure, burning mouth syndrome and male fertility rated limited; dementia rated insufficient.