The short answer
Some St. John’s wort products lower digoxin levels after repeated use. Ask your clinician before starting or stopping them; a few hours of separation is not an established solution.
What this answer covers
Oral Hypericum extracts with oral digoxin, with hyperforin content and repeated use explicitly relevant.
- Supplement or preparation
- Hypericum perforatum
- Medication ingredient
- digoxin
Repeated use changed digoxin levels
In a placebo-controlled study, a defined St. John’s wort extract caused no significant first-dose change but lowered digoxin exposure after10days. The current digoxin label also lists St. John’s wort among products that can lower concentrations. This is a drug-level interaction, not just laboratory assay interference.
Not all products had the same effect
A larger study compared ten Hypericum products. Higher-hyperforin products reduced digoxin exposure, whereas several low-hyperforin preparations and other formulations did not show a significant interaction. Those results do not authenticate a product currently sold as low-hyperforin or guarantee safety without review.
Plan starting and stopping with the clinician
The effect developed over repeated treatment, so spacing tablets by a few hours is not an established solution. Tell the prescribing team before starting, changing or stopping St. John’s wort. The team may check digoxin concentrations and adjust treatment according to results; do not calculate a dose change yourself.
Know when to seek assessment
Contact your clinician about new nausea, loss of appetite, visual changes, marked weakness or an unusually slow or irregular pulse. These may have several causes, including digoxin toxicity. Blood results must be interpreted with symptoms, kidney function and electrolytes; do not adjust digoxin yourself.
Evidence and practical considerations
Absorption & effectiveness
Repeated high-hyperforin St. John’s wort exposure can lower digoxin concentrations; the effect differs among preparations.
- Exact scope
- Oral Hypericum extracts with oral digoxin, with hyperforin content and repeated use explicitly relevant. with Exact digoxin RxCUI3407 IN, confirmed by current RxNorm. Oral125/250microgram tablets; oral absorption evidence is not transferred to IV digoxin. Digoxin is distinct from digitoxin.
- Medication form and route
- Oral
What remains uncertain
- Defined products and healthy volunteers; no universal effect size or short spacing rule. Clinical outcomes were not measured.
Factors that may matter: Exact preparation and dose; Kidney function; Baseline electrolyte status; Other medicines.
Read the supporting source summaries
Source 1: Current prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed oral digoxin tablets.
Antacids and St.John’s wort can lower concentrations. Hypokalemia, hypomagnesemia and hypercalcemia predispose to toxicity; assess electrolytes/renal function. Some substances interfere with assays without proving increased drug exposure.
How this applies: Exact medication label. Exact digoxin RxCUI3407 IN, confirmed by current RxNorm. Oral125/250microgram tablets; oral absorption evidence is not transferred to IV digoxin. Digoxin is distinct from digitoxin.
No universal nutrient spacing or vitaminD replacement need. Clinical state, assay method and formulation must be considered.
Source 2: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 25 healthy volunteers in a single-blind placebo-controlled parallel study.
No first-dose change; after10days digoxin AUC fell25%, with reduced peak and trough concentrations.
How this applies: Applicability is limited to the stated exact medication, preparation and endpoint; other-drug evidence is indirect.
Abstract-only; defined extract and healthy population. Does not establish identical effect for all products or clinical event incidence.
Source 3: Original clinical research
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 96 healthy volunteers in three study parts.
High-hyperforin products reduced exposure; several low-hyperforin products, tea, juice and oil preparations had no significant interaction.
How this applies: Applicability is limited to the stated exact medication, preparation and endpoint; other-drug evidence is indirect.
Abstract-only; product-dependent findings do not authenticate a currently sold low-hyperforin product or guarantee clinical safety.
Source 4: Medication terminology
rxnav.nlm.nih.gov · Source check Sep 10, 2026
Population: Terminology.
digoxin is IN.
How this applies: Exact ingredient.
Not clinical evidence.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Sources checked and article drafted. | |
| Research summary published |
Article revision: c20b17732538138b
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.