The short answer
If you take primidone during pregnancy, discuss vitamin K1 with your obstetric and epilepsy teams before delivery. Product labels recommend it, but evidence for routine maternal supplementation is uncertain.
What this answer covers
Vitamin K1/phytomenadione around pregnancy and delivery; maternal oral treatment is distinct from newborn prophylaxis, vitamin K2 and routine adult supplementation.
- Supplement or preparation
- Vitamin K1
- Medication ingredient
- primidone
What the labels recommend
US and UK primidone labels advise vitamin K1 near the end of pregnancy because neonatal clotting problems have been reported. This recommendation concerns pregnancy and delivery, not every adult taking primidone.
Why the outcome evidence is uncertain
A prospective cohort found no significant excess neonatal bleeding overall without maternal K1, but included only 11 primidone exposures. All newborns received K1 at birth. The AAN evidence review found insufficient evidence for routine maternal benefit.
Maternal and newborn treatment are separate
Do not interpret uncertainty about prenatal supplementation as a reason to omit the baby’s planned prophylaxis. Ask the maternity team to coordinate the maternal and newborn plans and the exact vitamin K form.
Keep the prescribed medicine steady
Do not stop primidone abruptly or adjust its dose to compensate for a supplement. Sudden withdrawal can provoke serious seizures. Tell the prescriber about new or worsening symptoms and all supplement changes.
Evidence and practical considerations
Timing & monitoring
Labels recommend maternal K1 near delivery, whereas evidence review found insufficient support for routine maternal benefit; management must be individualized.
- Exact scope
- Vitamin K1/phytomenadione around pregnancy and delivery; maternal oral treatment is distinct from newborn prophylaxis, vitamin K2 and routine adult supplementation. with Exact oral primidone; parent and metabolites distinguished; no other drug/route assumed equivalent.
- Medication form and route
- oral supplement unless pregnancy section explicitly distinguishes neonatal injection
- Timing or duration
- Preparation, dose and duration determine applicability; chronic nutrition evidence is not a single-dose interaction.
What remains uncertain
- Few primidone-exposed newborns in the cohort, no maternal-randomized trial, and all infants received neonatal K1. Cannot infer no newborn prophylaxis is needed.
Factors that may matter: exact supplement identity; dose; other medicines; clinical indication; baseline nutrition; pregnancy where relevant.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed oral primidone for epilepsy.
Primidone itself and its phenobarbital and PEMA metabolites have anticonvulsant activity. Drowsiness, ataxia and vertigo can occur. Rare megaloblastic anemia may respond to folic acid without stopping therapy. Label advises maternal vitamin K1 around delivery. Abrupt withdrawal can provoke status epilepticus.
How this applies: Exact RxCUI 8691 IN primidone, UNII 13AFD7670Q, oral tablets.
Parent and metabolites are distinct active exposures. Pregnancy label advice is not proof of benefit for routine prenatal vitamin K or a general adult supplement requirement.
Source 2: current product label
medicines.org.uk · Source check Sep 10, 2026
Population: Patients receiving oral primidone for epilepsy or essential tremor.
Potent CNS depressant; long-term vitamin D supplementation may be needed. Lists folates among co-treatments requiring attention; megaloblastic anemia can respond to folic acid/B12. St John’s wort is listed under contraindicated co-use because primidone concentrations and effectiveness may decrease. Maternal vitamin K1 is advised near delivery.
How this applies: Exact primidone label supports ingredient-specific boundaries rather than inference solely from phenobarbital metabolism.
Does not quantify botanical interactions or make parent and metabolite concentrations equivalent. Maternal vitamin K guidance differs from evidence reviews. No universal supplement spacing.
Source 3: original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 662 pregnancies with enzyme-inducing antiseizure drugs; 667 neonates, including 11 primidone exposures.
Bleeding risk was not significantly increased versus matched controls after adjustment. Authors allowed possible need for maternal K in selected cases.
How this applies: Apply only to the named drugs and study exposures; no unmeasured parent/metabolite or preparation equivalence.
Only 11 primidone exposures; pooled result cannot exclude an exact-drug risk. Neonatal prophylaxis was given, so this cannot support omitting the newborn dose.
Source 4: original guideline summary
aan.com · Source check Sep 10, 2026
Population: Pregnant people with epilepsy and their newborns.
Found insufficient evidence to support or refute benefit from maternal prenatal vitamin K for neonatal bleeding prevention; distinguished routine newborn prophylaxis.
How this applies: Makes label-versus-outcome-evidence uncertainty explicit for primidone; no general adult vitamin K1 requirement.
Older guideline, not a randomized trial. Does not overrule an individual obstetric plan; labels continue to recommend prenatal prophylaxis.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Exact current available claims reviewed against captured originals; no clinical review asserted. | |
| Research summary published |
Article revision: 136330577f1116b8
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.