# Foxglove (Digitalis purpurea) **Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/foxglove **Data Source:** Hermetica Superfoods Ingredient Encyclopedia **Updated:** 2026-03-19 **Evidence Score:** 8 / 10 **Category:** European **Also Known As:** Digitalis purpurea, Purple foxglove, Common foxglove, Lady's glove, Dead man's bells, Fairy gloves, Witches' gloves, Digitalis ## Overview 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. ## Health Benefits • Heart failure support: Purified derivatives like digoxin from foxglove have shown benefit in chronic heart failure patients with S3 gallop (evidence from double-blind trials, though specific to purified compounds, not raw herb) • Cardiac rhythm regulation: Traditional use since 1785 for strengthening heart contraction and regulating rhythm, though modern use limited to purified forms due to toxicity concerns • Potential anticancer activity: In vitro studies show cytotoxic activity of leaf extracts against cancer cell lines (IC50 0.78-15 μg/mL), particularly renal adenocarcinoma, but no human trials exist • Edema reduction: Historically used for "dropsy" (edema from heart failure) as documented by William Withering in 1785, though no modern clinical trials on raw herb • Enhanced cardiac contractility: Cardiac glycosides inhibit Na+/K+-ATPase, increasing intracellular calcium to enhance heart muscle contraction (mechanism established for purified compounds) ## 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 Summary 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. ## 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. ## Dosage & 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. ## Safety & Drug 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. ## 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. ## Historical & Cultural Context 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. ## Synergistic Combinations Hawthorn, Motherwort, Lemon Balm, Magnesium, CoQ10 ## Frequently Asked Questions ### Can you take foxglove herb instead of prescribed digoxin? No. Foxglove herb should never be substituted for prescribed digoxin. The raw plant lacks standardized potency, and its cardiac glycoside content varies widely between plants, plant parts, and growing conditions. Foxglove powder is approximately 300 times less potent than purified digoxin, making accurate dosing impossible. Using raw foxglove in place of a calibrated pharmaceutical carries serious risk of under-dosing your heart condition or, conversely, fatal cardiac toxicity. Always use only the form prescribed by your physician. ### What are the symptoms of foxglove poisoning? Foxglove poisoning symptoms stem from excessive cardiac glycoside activity and include nausea, vomiting, severe abdominal pain, slow or irregular heartbeat (bradycardia, heart block), visual disturbances such as yellow-green halos, confusion, and potentially fatal ventricular arrhythmias. Symptoms can appear after ingesting any plant part, including leaves, seeds, or flowers. If foxglove ingestion is suspected, this constitutes a medical emergency requiring immediate contact with poison control or emergency services, as there is a very narrow margin between a therapeutic and lethal dose. ### Does foxglove have any proven anticancer benefits in humans? Currently, no. In vitro studies have shown cytotoxic activity of Digitalis purpurea leaf extracts against cancer cell lines, including renal adenocarcinoma, with IC50 values ranging from 0.78 to 15 μg/mL. However, these are laboratory findings only. No human clinical trials exist examining foxglove extracts as a cancer treatment. The significant toxicity of the plant further limits its therapeutic development. Researchers continue to investigate cardiac glycoside derivatives in oncology, but no foxglove-based cancer supplement is clinically validated or recommended. ### How does foxglove strengthen the heart muscle? Foxglove contains cardiac glycosides, primarily digoxin and digitoxin, which bind to and inhibit sodium-potassium ATPase pumps in cardiac cell membranes. This inhibition raises intracellular sodium levels, which in turn triggers the sodium-calcium exchanger to increase intracellular calcium. Elevated calcium enhances the force of myocardial contractions, a property called positive inotropy. The compounds also slow electrical conduction through the atrioventricular node, reducing heart rate. These mechanisms are well established for purified pharmaceutical digoxin, not for raw foxglove preparations. ### What did William Withering discover about foxglove? In 1785, British physician William Withering published his landmark work documenting the medicinal use of foxglove for treating 'dropsy,' which is now understood as edema resulting from congestive heart failure. He systematically recorded over 160 clinical cases and identified the dried leaf as the active component. Withering's work marked one of the earliest applications of the scientific method to herbal medicine and directly led to the eventual isolation and pharmaceutical development of digoxin, which remains a prescribed cardiac medication in use today. ### Are there any foxglove supplements legally available to buy? Foxglove is not legally sold as a dietary supplement in most countries, including the United States, due to its extremely narrow therapeutic index and high toxicity risk. Regulatory bodies like the FDA do not recognise Digitalis purpurea as a safe supplement ingredient. While dried foxglove leaves or powders may occasionally appear online, their sale for human consumption is generally considered illegal or heavily restricted. If you have a legitimate medical need for cardiac glycoside therapy, only physician-prescribed pharmaceutical digoxin should be used. ### Can foxglove interact with common heart or blood pressure medications? Yes, significantly. The cardiac glycosides in foxglove interact dangerously with numerous medications. Concurrent use with antiarrhythmics such as amiodarone, beta-blockers, or calcium channel blockers can cause severe bradycardia or heart block. Diuretics that deplete potassium increase cardiac glycoside toxicity by lowering the competing ion. Antibiotics, certain antifungals, and other drugs that inhibit P-glycoprotein can elevate glycoside blood levels dangerously. Even for prescribed pharmaceutical digoxin, drug interactions require careful medical monitoring, making unsupervised use of any foxglove-containing product extremely hazardous. ### Why is foxglove not used as a herbal remedy despite its long history? Despite over 200 years of medicinal history, raw foxglove is not used therapeutically today because its cardiac glycoside content varies significantly between plants, making consistent dosing impossible. The margin between a therapeutic dose and a lethal dose is extremely narrow. Modern medicine instead uses precisely calibrated pharmaceutical digoxin isolated from Digitalis lanata, allowing blood level monitoring and standardised dosing. No human clinical trials support the safety or efficacy of raw foxglove herb or standardised extracts, leaving no evidence base to justify its use over safer, proven alternatives. ### 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. --- *Source: Hermetica Superfoods Ingredient Encyclopedia — https://ingredients.hermeticasuperfoods.com* *License: CC BY-NC-SA 4.0 — Attribution required. Commercial use: admin@hermeticasuperfoods.com*