Can I Take Vitamin B6 with Provigil (Modafinil)?

What Is the Interaction Between Vitamin B6 and Provigil?

There is no established direct drug-supplement interaction between vitamin B6 and modafinil in the peer-reviewed literature or major interaction databases. The two compounds do not share a metabolic pathway in a way that would cause one to raise or lower the blood concentration of the other at typical doses.

That does not mean combining them is entirely without nuance. Modafinil is a schedule IV wakefulness-promoting agent approved by the FDA for narcolepsy, shift-work sleep disorder, and obstructive sleep apnea adjunct therapy [1]. Vitamin B6 is a water-soluble cofactor involved in over 100 enzymatic reactions, including neurotransmitter synthesis [2]. The overlap between modafinil's dopaminergic and noradrenergic activity and B6's role in catecholamine biosynthesis raises a theoretical pharmacodynamic question, but no clinical trial has quantified that effect as a meaningful risk at supplemental doses.

How Modafinil Is Metabolized

Modafinil is absorbed orally, reaches peak plasma concentration in 2 to 4 hours, and is metabolized primarily in the liver by CYP3A4 and CYP3A5, with secondary involvement of amide hydrolysis [3]. Its half-life is approximately 15 hours. Modafinil also modestly induces CYP3A4 and inhibits CYP2C19, which matters when co-prescribing certain anticonvulsants or hormonal contraceptives, but B6 is not a substrate, inhibitor, or inducer of any of these enzymes at physiological or supplemental concentrations.

How Vitamin B6 Is Processed

Dietary and supplemental B6 is converted in the liver and red blood cells to pyridoxal-5-phosphate (PLP), the active coenzyme form [2]. Excess B6 is excreted renally. PLP does not enter cytochrome P450 pathways as a substrate or modulator. This means modafinil clearance is not expected to change based on B6 intake, and B6 plasma levels are not expected to shift because of modafinil use.

Is Vitamin B6 Safe at Standard Doses When Taking Modafinil?

Yes. At doses up to 100 mg/day, vitamin B6 is considered safe for the general adult population and does not interact with modafinil's pharmacokinetics or its primary mechanism of action [4]. The NIH Office of Dietary Supplements sets the Tolerable Upper Intake Level (UL) for adults at 100 mg/day specifically because evidence of sensory neuropathy appears at chronic intakes above that threshold [4].

Most multivitamins contain 1.7 to 2 mg of B6, well below any concern. Single-ingredient B6 supplements sold over the counter often range from 25 mg to 500 mg per tablet, and the higher-dose products are where risk accumulates, regardless of whether modafinil is involved.

The Peripheral Neuropathy Risk From High-Dose B6

The key concern with B6 supplementation is sensory peripheral neuropathy. A 1983 case series published in the New England Journal of Medicine first described seven patients who developed progressive sensory ataxia and neuropathy after taking 2,000 mg or more of pyridoxine daily [5]. Subsequent reports identified toxicity at lower doses taken over longer periods. A 2023 systematic review in the journal Nutrients analyzed 35 published neuropathy cases and found that toxicity had been reported at doses as low as 24 mg/day with prolonged use, though the median toxic dose in that cohort was 152 mg/day [6].

Modafinil does not appear to potentiate B6 neurotoxicity based on available pharmacological data. The neuropathy is caused by direct PLP toxicity to dorsal root ganglion neurons when plasma B6 concentrations exceed a saturation threshold, a process unrelated to dopamine reuptake inhibition or orexin system modulation [5].

Symptoms to Watch

Symptoms of B6 toxicity include numbness or tingling in the hands and feet, unsteady gait, reduced vibration sense, and photosensitivity. These typically resolve after stopping high-dose supplementation, though recovery may take months [5]. Anyone on modafinil who adds a B6 supplement above 50 mg/day should watch for these signs and report them promptly to their prescriber.

Does Vitamin B6 Affect Modafinil's Wakefulness Effects?

No evidence from clinical trials shows that B6 supplementation changes modafinil's wakefulness, cognitive, or mood effects. Modafinil promotes wakefulness primarily by inhibiting dopamine reuptake at the dopamine transporter (DAT), which increases extracellular dopamine in the brain [7]. It also activates hypothalamic orexin (hypocretin) neurons and norepinephrine release [7].

Vitamin B6 as PLP is a cofactor in the synthesis of dopamine, serotonin, and GABA from their amino acid precursors [2]. A hypothetical interaction might involve B6 status influencing baseline neurotransmitter tone, but no study has shown that supplementing B6 in a person with adequate baseline B6 status meaningfully alters the efficacy of modafinil. Severe B6 deficiency is rare in developed countries, and correcting it would not be expected to blunt or amplify a DAT inhibitor's pharmacological activity.

Theoretical Pharmacodynamic Overlap

The following framework is used by the HealthRX clinical team to classify supplement-modafinil interactions by mechanism:

Category A (pharmacokinetic, CYP-mediated): Supplements that induce or inhibit CYP3A4 or CYP2C19, changing modafinil or its metabolite concentrations. Examples include St. John's Wort (CYP3A4 inducer) and high-dose grapefruit compounds (CYP3A4 inhibitor). B6 does not belong in this category.

Category B (pharmacodynamic, same receptor/transporter): Supplements that act at DAT, norepinephrine transporter, or orexin receptors. Tyrosine, a dopamine precursor, could theoretically fit here. B6 alone does not act at these transporters directly.

Category C (indirect neurotransmitter cofactor): Supplements whose deficiency states affect neurotransmitter synthesis. B6 belongs here. Clinical relevance at supplemental doses in replete individuals: low.

Category D (independent toxicity risk): Supplements with their own adverse effect profile that warrants monitoring regardless of modafinil co-administration. B6 above 100 mg/day belongs here.

This framework places B6 in Categories C and D. There is no pharmacokinetic interaction, and the pharmacodynamic overlap is indirect and not clinically significant at standard doses.

When Does Vitamin B6 Become Clinically Relevant for Modafinil Users?

B6 becomes clinically relevant in three specific scenarios for people using modafinil.

Scenario 1: B6 as Adjunct Therapy for Drug-Induced Neuropathy

Certain drugs, including isoniazid, hydralazine, and penicillamine, deplete B6 and cause peripheral neuropathy by competing with or inactivating PLP [8]. In those situations, supplemental B6 at 25 to 50 mg/day is standard prophylaxis [8]. If a person is taking modafinil for shift-work sleep disorder and also taking isoniazid for latent tuberculosis, co-administration of all three is common and generally safe, provided the B6 dose stays below 100 mg/day.

Scenario 2: High-Dose B6 for Premenstrual Syndrome

Some individuals use B6 at 50 to 100 mg/day for premenstrual syndrome symptom management, a use supported by moderate evidence in a Cochrane review of 9 trials [9]. Women using modafinil off-label for cognitive support who add B6 for PMS are combining two agents with overlapping CNS activity domains. The combination remains pharmacokinetically safe. The practical instruction is to stay at or below 100 mg/day of B6 and report any new sensory symptoms.

Scenario 3: Stack-Based Nootropic Use

Off-label modafinil use for cognitive enhancement is common; a 2016 survey published in Nature found that 14% of scientists had used modafinil without a prescription for cognitive purposes [10]. Many of these users combine it with B-vitamin complexes, racetams, or choline sources. B6 in this context is often part of a B-complex at low doses (under 50 mg), which poses no pharmacokinetic concern with modafinil. The risk arises when high-dose standalone B6 tablets (100 to 500 mg) are added without medical oversight.

What Does the FDA Label for Provigil Say About Supplements?

The FDA-approved prescribing information for Provigil does not list vitamin B6 or pyridoxine as a contraindicated or cautioned co-administration [1]. The label does highlight CYP3A4 inducers and inhibitors, CYP2C19 substrates, and hormonal contraceptives as interaction classes requiring attention [1]. The absence of B6 from the drug label is consistent with the lack of a documented pharmacokinetic mechanism of interaction.

The Provigil label also notes that modafinil is "highly bound to plasma protein (approximately 60%)" and lists the potential for interaction with highly protein-bound drugs [1]. B6 is not highly protein-bound in a competitive sense; PLP binds to albumin but not at sites that displace modafinil.

CYP Enzyme Context

To confirm the lack of a CYP-based interaction: a pharmacokinetic study in healthy volunteers established that modafinil at 400 mg/day for 7 days produced a 32% decrease in midazolam AUC via CYP3A4 induction and a 40% decrease in omeprazole AUC via CYP2C19 induction [3]. Neither B6 nor its active form PLP was involved in or affected by these inductions. The enzymes that process B6 (pyridoxal kinase, pyridoxal phosphate oxidase) are distinct from cytochrome P450 enzymes [2].

Dosing Guidance: B6 Alongside Modafinil

Dose selection for B6 when using modafinil should follow the same evidence-based ceiling as the general population: keep total daily B6 intake from all sources below 100 mg [4]. For most people, this means:

• Dietary B6 from food (average adult intake: 1.5 to 2 mg/day from meat, fish, potatoes, and non-citrus fruit) [4]
• A standard multivitamin (1.7 to 25 mg B6, depending on formulation)
• A low-dose standalone B6 supplement if therapeutically indicated (25 to 50 mg/day)

There is no documented clinical benefit to taking B6 above 100 mg/day in combination with modafinil, and doing so adds neuropathy risk without established cognitive gain.

Timing and Separation

Because no pharmacokinetic interaction exists, there is no clinically required dose-separation window between modafinil and B6. They may be taken at the same time of day without one affecting the absorption or peak concentration of the other. Modafinil is typically taken once in the morning (100 mg or 200 mg) for narcolepsy or obstructive sleep apnea, or approximately 1 hour before a work shift for shift-work sleep disorder [1]. B6 can be taken at the same time or with any meal.

Monitoring Parameters

Patients combining modafinil with B6 supplements above 50 mg/day should be assessed periodically for:

• New onset paresthesia (numbness, tingling) in hands or feet
• Gait instability or proprioception changes
• Photosensitivity
• Worsening of any pre-existing peripheral neuropathy

These are signs of B6 toxicity, not a modafinil-B6 interaction per se, but they should prompt review of both the supplement dose and any other potential contributing factors.

What the Research Gaps Mean for Clinical Practice

No randomized controlled trial has examined B6 supplementation specifically in modafinil users. The absence of trial data does not indicate harm; it reflects the low prior probability of a meaningful interaction given the non-overlapping metabolic pathways. The American Society of Health-System Pharmacists and peer-reviewed interaction databases such as the Natural Medicines database (formerly Natural Standard) classify the B6-modafinil combination as having no documented interaction [11].

Clinicians who prescribe modafinil should ask patients about all OTC supplements at every visit. A 2017 JAMA Internal Medicine study found that 34% of Americans use both prescription medications and dietary supplements concurrently, with fewer than half of them disclosing supplement use to their physician [12]. B6 is among the most common single-nutrient supplements sold in the United States, making this disclosure gap clinically relevant even when the interaction risk is low.

Specific Population Notes

Older adults: Age-related declines in renal function can slow B6 excretion, increasing the risk of accumulation at doses above 50 mg/day. Modafinil is used off-label in some older adults for excessive daytime sleepiness in neurodegenerative conditions. In this population, B6 doses above 50 mg/day warrant extra caution.

Pregnancy: Modafinil is FDA Pregnancy Category C (risk cannot be ruled out) and is generally avoided in pregnancy [1]. B6 at 10 to 25 mg is a first-line treatment for nausea and vomiting of pregnancy per ACOG guidelines [13]. If a patient becomes pregnant while taking modafinil, that is a separate clinical discussion; the B6 dose used for pregnancy nausea (10 to 25 mg) presents no additional interaction concern.

Renal impairment: Reduced GFR slows pyridoxine clearance. Patients with GFR below 30 mL/min/1.73m² should limit supplemental B6 to the lowest effective dose and have plasma PLP levels monitored if taking more than 25 mg/day.