The short answer
Avoid oral comfrey while taking valproate and tell your prescriber if you have used it. Comfrey can contain compounds toxic to the liver, and valproate has a separate liver warning. This does not establish that the combination has been shown to cause more injury than either exposure alone.
What this answer covers
Symphytum officinale root oral-toxicity information, with indirect leaf-ingestion case context of unconfirmed exact species. Specified topical medicinal preparations are a different exposure.
- Supplement or preparation
- Symphytum officinale
- Medication ingredient
- valproate
Why oral use raises concern
The European assessment identifies liver-toxic pyrrolizidine alkaloids in Symphytum officinale root when taken by mouth. An older case also described fatal liver disease after comfrey leaf ingestion, although the abstract does not verify the exact plant species.
Creams and swallowed products are different
The European medicinal assessment concerns specified topical root preparations. It does not make homemade, swallowed or differently formulated products equivalent. Bring the label and route of use to your pharmacist for a product-specific review.
What is known about the combination
Valproate can itself cause serious liver injury. These sources support avoiding an unnecessary oral liver-toxic exposure, but they do not measure added risk with valproate or establish that taking the products hours apart prevents harm.
Review use and symptoms with your clinician
Bring the product label and your dose and duration of use to your prescriber. Valproate requires liver monitoring, especially early in treatment. Seek prompt medical assessment for new loss of appetite, vomiting, marked weakness or unusual lethargy. Do not abruptly stop an anticonvulsant prescribed for epilepsy; medication decisions need your treating team.
Evidence and practical considerations
Side effects & toxicity
Oral comfrey presents a liver-toxicity concern relevant to valproate monitoring, although increased injury from the exact combination has not been demonstrated.
- Exact scope
- Symphytum officinale root oral-toxicity information, with indirect leaf-ingestion case context of unconfirmed exact species. Specified topical medicinal preparations are a different exposure. with Oral valproate active moiety; label evidence is from oral valproic acid capsules, with Depakote exposure identified separately where relevant.
- Medication form and route
- oral valproate; supplement route as specified in source and scope
- Timing or duration
- No safe co-use duration or protective spacing interval established.
What remains uncertain
- The fatal leaf case lacks authenticated species in the abstract; the EMA exact-species root warning is distinct from that case and from topical-use assessments.
Factors that may matter: oral use; pyrrolizidine alkaloid content; existing liver disease.
Read the supporting source summaries
Source 1: current oral product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed oral valproic acid capsules.
Label warns of potentially fatal liver injury, especially during the first six months, and thrombocytopenia/coagulation abnormalities. It recommends baseline and follow-up liver and blood assessments. P450 oxidation is a minor metabolic pathway. Aspirin increased free valproate fraction in six pediatric patients; the study is aspirin-specific.
How this applies: Medication risk and identity context for RxCUI 40254 valproate; oral active-moiety bridge only.
Not a study of any of these botanical combinations. Active-moiety identity does not establish interchangeable doses, release kinetics or routes. Aspirin results do not establish salicin or methyl salicylate effects.
Source 2: EMA herbal monograph or public assessment summary
ema.europa.eu · Source check Sep 10, 2026
Population: People considering the specified herbal medicinal preparations.
Symphytum officinale root contains pyrrolizidine alkaloids with toxic effects on the liver when taken by mouth. Evaluated medicinal uses concern specified topical preparations.
How this applies: Exact-species oral liver-toxicity context, while preserving distinction from regulated topical root products.
No valproate co-use study. This summary is not used for a current numerical PA limit or to guarantee safety of all topical products.
Source 3: fatal hepatic veno-occlusive disease case report
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 23-year-old man.
Hepatic veno-occlusive disease, portal hypertension and fatal liver failure; a possible causal association was proposed after consideration of other causes.
How this applies: Indirect comfrey-ingestion context only; the EMA source supplies explicit S. officinale root identity. Do not transfer leaf case severity or frequency to all species or preparations.
The abstract does not authenticate exact Symphytum species or product composition. No valproate exposure identified.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Original sources checked and exact-pair evidence package prepared; no clinical review asserted. | |
| Research summary published |
Article revision: 9beea8c72b3d0a7a
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.