ModerateCaution
Melatonin
Melatonin can add to primidone and phenobarbital-metabolite sedation.
Recommendation: Use cautiously and avoid driving if impaired.
Primidone
Prescription ·Strong evidence ·Reviewed May 2026
Primidone is an anticonvulsant used for seizure disorders and commonly used off-label for essential tremor. It is metabolized partly to phenobarbital and phenylethylmalonamide, so sedation, ataxia, dependence-related concerns, and enzyme-induction effects can occur. Long-term therapy can contribute to vitamin D, calcium, and folate problems through phenobarbital-like enzyme induction.
The bottom line
Evidence rating strong. Most-documented uses: treatment of generalized tonic-clonic and focal seizures, adjunctive antiseizure therapy, reduction of essential tremor symptoms when prescribed by a clinician. 3 sources indexed (2004–2025), with 4 interaction records on file.
The science
How it works, mechanistically.
Core mechanism
Primidone and its active metabolites reduce neuronal excitability through barbiturate-like enhancement of GABAergic inhibition and other antiseizure effects. Phenobarbital formation contributes both efficacy and adverse effects, including sedation and hepatic enzyme induction. Enzyme induction can accelerate vitamin D catabolism and alter folate metabolism, contributing to bone and hematologic complications during chronic use.1,3
Class
Anticonvulsant metabolized to phenobarbital
Absorption
Water-soluble; take with food
Dosing
Dosing & protocol.
Common range
For seizures, start very low, often 100-125 mg at bedtime or 50 mg/day in sensitive patients, then titrate gradually. Common maintenance is 250 mg three or four times daily; doses should not exceed 500 mg four times daily.
Recommended form
Oral tablet with slow titration
May be taken with food to reduce nausea. Slow titration reduces acute sedation, dizziness, and ataxia.
Depletions
What it depletes.
Nutrients this medication can lower over time, and what to replace.
Vitamin D
SignificantPrimidone's phenobarbital metabolite and enzyme-inducing effects accelerate vitamin D catabolism.
Calcium
ModerateLower vitamin D activity reduces intestinal calcium absorption and can contribute to bone loss.
Replace CalciumMonitor Serum calcium, parathyroid hormone, and bone density when indicatedOnset Months to years, usually secondary to vitamin D changes
Folate
ModerateChronic older anticonvulsant therapy can lower folate status and contribute to megaloblastic anemia.
Replace MethylfolateMonitor CBC, serum folate, red blood cell folate, and homocysteineOnset Months to years
Safety
Full safety detail.
Side effects
- Sedation
- Dizziness
- Ataxia
- Nausea
- Vomiting
- Diplopia
- Cognitive slowing
- Mood changes
- Megaloblastic anemia
- Bone loss or osteomalacia with chronic use
- Rash or hypersensitivity
- Suicidal thoughts or behavior warning for antiepileptic drugs
Interactions
Interaction records.
ModerateCaution
Ashwagandha
Ashwagandha may add to primidone-related sedation or dizziness.
Recommendation: Avoid during titration and use cautiously if stable.
ModerateConflict
Ginkgo Biloba
Ginkgo may lower seizure threshold and is undesirable with anticonvulsant therapy.
Recommendation: Avoid ginkgo if primidone is used for seizure prevention.
ModerateCaution
St. John's Wort
St. John's Wort adds enzyme induction to primidone's enzyme-inducing metabolite burden and can reduce exposure to many co-medications.
Recommendation: Avoid unless a clinician reviews all medications for induction-sensitive interactions.
Sources
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Reviews & position papers
2- 1Evidence-based guideline update: treatment of essential tremorNeeds reviewNo linkZesiewicz TA et al. · Neurology · 2011
Guideline identifies primidone as an established therapy for essential tremor.
- 2Antiepileptics and bone healthNeeds reviewNo linkPack AM · Current Opinion in Neurology · 2004
Review links older enzyme-inducing antiseizure drugs with altered vitamin D metabolism and bone disease.
Reference material
1- 3PRIMIDONE tablets, US Prescribing InformationNeeds reviewURLU.S. National Library of Medicine · DailyMed · 2025
Labeling describes titration, maintenance dosing, maximum dosing, contraindications, and withdrawal seizure risk.
Keep exploring
Deep dives & adjacent profiles.
This page is educational. Do not start, stop, or change a supplement or medication based on it without checking with a qualified healthcare professional.
Use this with your stack
Primidone in NutriStack.
Add it to your stack, see how it interacts with everything else you take, and get a Stack Score that updates the moment it does.