Section 06 · Monograph

Alpha-lipoic acid

Reviewed Nov 2026FDA label

generic/supplementAntioxidant supplement

Indications

Not FDA-approved as a drug; alpha-lipoic acid (thioctic acid) is marketed and regulated in the United States as a dietary supplement, not subject to FDA drug efficacy/safety review, and carries no FDA-approved therapeutic indicationFDA-labeled

Diabetic peripheral neuropathy — symptomatic relief of pain, paresthesia, and numbness, based on clinical trial evidence including the ALADIN and SYDNEY randomized controlled trials, most using intravenous or oral doses of approximately 600 mg/dayOff-label
Adjunctive antioxidant support in diabetes-related oxidative stress, based on mechanistic and small clinical trial evidence rather than regulatory approvalOff-label

Naturally occurring, endogenously synthesized cofactor for mitochondrial enzyme complexes involved in oxidative energy metabolism
Functions as a potent antioxidant in both its oxidized and reduced forms, scavenging reactive oxygen and nitrogen species implicated in the pathogenesis of diabetic neuropathy
Proposed mechanism in diabetic neuropathy centers on reduction of oxidative stress-mediated microvascular endoneurial damage and improvement of nerve blood flow
May also regenerate other endogenous antioxidants (vitamin C, vitamin E, glutathione) and chelate certain transition metals that catalyze free-radical generation

No FDA-established dosing exists since this is a dietary supplement; dosing reflects regimens studied in clinical trials, not an approved label
Oral dosing commonly studied/used clinically: 600 mg once daily (range roughly 300-1800 mg/day in various trials), often taken on an empty stomach to enhance absorption
Intravenous dosing used in pivotal European trials: 600 mg/day IV for 2-4 weeks, sometimes followed by oral maintenance therapy — IV formulation not routinely available in standard US practice
Supplement products are not standardized or FDA-verified for potency/purity

Known hypersensitivity to alpha-lipoic acid or thioctic acid
Caution/relative avoidance in patients with thiamine (vitamin B1) deficiency — high-dose alpha-lipoic acid has been associated with seizures and other serious adverse effects in this setting
Caution in patients on insulin or insulin secretagogues given potential additive blood-glucose-lowering effect

May have additive glucose-lowering effects with antidiabetic medications, increasing hypoglycemia risk — blood glucose monitoring advised
Theoretical interaction with chemotherapy agents due to antioxidant effects potentially interfering with pro-oxidant mechanisms — clinical significance not well established
Possible interaction with thyroid hormone (levothyroxine) absorption/metabolism — limited evidence
No formal, rigorous drug-interaction studies have been conducted since ALA is not regulated as a pharmaceutical

Generally well tolerated; most trials report a safety profile similar to placebo
Gastrointestinal upset — nausea, vomiting, dyspepsia (most commonly reported)
Skin rash or allergic-type reactions (uncommon)
Hypoglycemia, particularly when combined with antidiabetic medications
Rare reports of insulin autoimmune syndrome/hypoglycemia in case reports
Rare seizures reported with high doses, particularly with underlying thiamine deficiency
Metallic/unusual taste with oral use

Monitor blood glucose closely, especially when initiating or adjusting dose in patients on concurrent insulin or insulin secretagogues
Assess neuropathic symptom severity periodically to gauge clinical benefit
Monitor for gastrointestinal tolerability, particularly at initiation
Counsel patients to choose reputable, third-party-tested products given lack of FDA pre-market verification of potency/purity

Safety in pregnancy has not been established through rigorous controlled human trials; use during pregnancy is generally not recommended outside of clinical guidance
Safety during lactation has not been well studied; no adequate data on excretion into human breast milk
General clinical practice recommendation is to avoid use during pregnancy and breastfeeding unless specifically advised by a treating clinician