Hermetica Superfood Encyclopedia
The Short Answer
Foxglove (Digitalis purpurea) contains cardiac glycosides including digoxin that strengthen heart muscle contractions by inhibiting sodium-potassium ATPase pumps. The raw plant is extremely toxic and only pharmaceutical preparations of isolated compounds are used medically.
CategoryHerbs (Global Traditional)
GroupEuropean
Evidence LevelStrong
Primary Keywordfoxglove benefits
Synergy Pairings3
Foxglove (Digitalis purpurea) — botanical close-up
Health Benefits
Origin & History
Natural habitat
Foxglove (Digitalis purpurea) is a biennial herbaceous plant native to western Europe, belonging to the Scrophulariaceae family, with leaves serving as the primary source for medicinal extracts. Extracts are typically obtained from dried leaves using methanolic or other solvent methods, yielding cardiac glycosides including digitoxin and related compounds as the main chemical constituents.
“Foxglove has been used in European traditional medicine since at least 1785, when William Withering documented its use for "dropsy" (edema from heart failure) and cardiac conditions. Traditionally applied as leaf infusions or powders to strengthen heart contraction and regulate rhythm, its use has declined in modern times due to toxicity concerns and the availability of purified alternatives.”Traditional Medicine
Scientific Research
Search results lack human clinical trials, RCTs, or meta-analyses specifically on Digitalis purpurea herb or extracts; evidence focuses on purified derivatives like digoxin. Two double-blind, placebo-controlled trials on digoxin (not raw herb) showed successful withdrawal in elderly patients with stable congestive heart failure and benefit in chronic heart failure patients with S3 gallop (sample sizes not specified in abstracts). No PubMed PMIDs for herb-specific RCTs were found.
Preparation & Dosage
Traditional preparation
No clinically studied dosage ranges for Digitalis purpurea herb, powder, or standardized extracts exist in human trials. Herb forms like powder are noted to be 300 times less potent than purified digoxin. Due to high toxicity risk and lack of standardized dosing data, self-use should be avoided. Consult a healthcare provider before starting any new supplement.
Nutritional Profile
Foxglove (Digitalis purpurea) is not a nutritional food source and contains no meaningful macronutrient profile for dietary purposes. Its significance lies entirely in its bioactive secondary metabolites. Cardenolide cardiac glycosides are the primary compounds: digoxin (0.1–0.3% dry weight of leaves), digitoxin (0.2–0.4% dry weight), and gitoxin (trace to 0.1% dry weight). Digoxin concentration varies significantly by plant part — mature second-year leaves harvested before flowering contain the highest glycoside concentrations. Lanatoside C (a precursor glycoside) is present at approximately 0.1–0.2% dry weight. Secondary bioactives include digitalinum verum, gitaloxin, and odoroside. Flavonoids including luteolin and apigenin glycosides are present at low concentrations (estimated 0.5–1% dry weight total). Anthraquinones are absent. Saponins occur at trace levels. Mineral content includes potassium, calcium, and magnesium in amounts typical of leafy plants but nutritionally irrelevant given toxicity constraints. Crude fiber is present as with most leaves (~15–20% dry weight) but not bioavailable for human dietary use. Protein content is approximately 10–15% dry weight, again irrelevant due to toxicity. Bioavailability note: cardiac glycosides are highly bioavailable orally (digoxin ~70–80% absorption), which underpins both therapeutic utility and extreme toxicity risk — the therapeutic index is dangerously narrow with toxic dose only marginally above therapeutic dose.
How It Works
Mechanism of Action
Foxglove's cardiac glycosides (digoxin, digitoxin) bind to and inhibit Na+/K+-ATPase pumps in cardiac cell membranes, increasing intracellular sodium levels. This leads to increased intracellular calcium through the sodium-calcium exchanger, resulting in stronger myocardial contractions (positive inotropy). The compounds also slow electrical conduction through the AV node, reducing heart rate.
Clinical Evidence
Purified digoxin from foxglove has demonstrated efficacy in heart failure patients in multiple randomized controlled trials, including the DIG trial with 6,800 participants showing reduced hospitalizations. Studies specifically examined patients with systolic heart failure and S3 gallop sounds. However, clinical evidence applies only to pharmaceutical-grade isolated compounds, not whole plant preparations. The raw herb lacks standardization and poses significant toxicity risks.
Safety & Interactions
Raw foxglove is extremely poisonous, with as little as 5 grams potentially fatal due to cardiac glycoside content. Symptoms include nausea, vomiting, irregular heartbeat, and cardiac arrest. Pharmaceutical digoxin interacts with numerous medications including diuretics, calcium channel blockers, and quinidine, requiring careful monitoring. Contraindicated in pregnancy and ventricular tachycardia, with narrow therapeutic window requiring regular blood level monitoring.
Synergy Stack
Hermetica Formulation Heuristic
Also Known As
Digitalis purpureaPurple foxgloveCommon foxgloveLady's gloveDead man's bellsFairy glovesWitches' glovesDigitalis
Frequently Asked Questions
Is foxglove safe to use as a herbal supplement?
No, raw foxglove is extremely toxic and potentially fatal. Only pharmaceutical preparations of isolated compounds like digoxin are safe for medical use under strict medical supervision with regular blood monitoring.
What is the difference between foxglove and digoxin?
Foxglove is the raw plant containing multiple cardiac glycosides, while digoxin is a purified, standardized compound extracted from foxglove. Digoxin is the FDA-approved medication used in hospitals for heart failure treatment.
How much foxglove is toxic?
As little as 5 grams of dried foxglove leaves can be fatal due to high concentrations of cardiac glycosides. Even smaller amounts can cause serious heart rhythm disturbances and require immediate medical attention.
Can foxglove help with irregular heartbeat?
Pharmaceutical digoxin derived from foxglove can help certain irregular heartbeats like atrial fibrillation by slowing AV node conduction. However, raw foxglove actually causes dangerous irregular heartbeats and should never be used for self-treatment.
What are the symptoms of foxglove poisoning?
Early symptoms include nausea, vomiting, loss of appetite, and visual disturbances including yellow halos around lights. Severe poisoning causes dangerous heart rhythm abnormalities, extremely slow or fast heart rate, and potentially fatal cardiac arrest.
Does foxglove interact with heart medications like beta-blockers or ACE inhibitors?
Yes, foxglove and its derivatives can have serious interactions with common cardiac medications, as both work on heart function through similar mechanisms. Combining foxglove with beta-blockers, ACE inhibitors, or other heart drugs significantly increases the risk of toxicity, arrhythmias, and overdose effects. Anyone taking prescription cardiac medications should never use foxglove supplements without explicit medical supervision, as dosing adjustments and careful monitoring are essential to prevent dangerous interactions.
Is foxglove safe for elderly patients or those with kidney disease?
Foxglove is particularly risky for elderly patients and those with impaired kidney function, as the body eliminates cardiac glycosides more slowly in these populations, leading to accumulation and toxicity. Age-related changes in heart function and kidney clearance make even small doses potentially dangerous in older adults. Medical professionals generally recommend avoiding foxglove supplements entirely in these groups, relying instead on pharmaceutical-grade, controlled digoxin if cardiac support is needed.
What clinical evidence supports using foxglove for heart conditions compared to modern pharmaceutical alternatives?
While foxglove derivatives like digoxin have robust clinical evidence from controlled trials for heart failure and atrial fibrillation, the evidence applies specifically to purified pharmaceutical forms with standardized dosing, not whole-herb supplements. Raw foxglove herb has highly variable cardiac glycoside content, making it impossible to achieve therapeutic doses safely or predictably. Modern cardiology has largely moved toward alternative medications with better safety profiles and more reliable dosing, reserving digoxin for specific cases where benefits clearly outweigh risks.
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