300–1,800 mg/day of standardized extract.
As an add-on, modestly improves symptoms and exercise tolerance.
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Hawthorn is a shrub of the genus Crataegus (with several medicinally interchangeable species: monogyna, oxyacantha, laevigata) whose leaves, flowers, and fruits have been used in traditional European medicine since antiquity for cardiovascular problems and for "nervous heart conditions"; it is one of the few herbal remedies with a cardiovascular indication supported by modern clinical trials of reasonable quality and with formal approval as an herbal medicine in Germany (Commission E) and in other European countries for mild heart failure.
The identified active constituents are oligomeric proanthocyanidins, flavonoids (vitexin, hyperoside, rutin), and related compounds that together exert mild positive inotropic effects (improved cardiac contractile force), coronary and peripheral vasodilation, mild modulation of heart rhythm, and antioxidant effects; standardized products in Europe (especially WS 1442) have been used in dozens of clinical trials and represent the extract with the best clinical documentation.
The indication with the best evidence is mild to moderate heart failure (NYHA classes II and III): multiple randomized trials and a Cochrane meta-analysis confirm significant improvements in exercise capacity, ejection fraction, and symptoms (dyspnea, fatigue) with the standardized extract WS 1442 at doses of 900 milligrams per day for 8-16 weeks, a clinically relevant and well-tolerated efficacy that justifies its use as an adjunct to conventional drug treatment.
The SPICE study, published in 2008 with more than 2,600 patients with class II-III heart failure, evaluated the WS 1442 extract added to standard treatment for 24 months; although it did not show a reduction in overall mortality, it did show improvements in functional capacity and reductions in sudden death in the subgroup with moderately reduced ejection fraction; later data have qualified but not invalidated the usefulness of the extract in compensated heart failure.
In mild hypertension, several small trials have shown modest reductions in systolic and diastolic blood pressure (around 5-10 mmHg) with the standardized extract at doses of 500-1,200 milligrams per day for 10-16 weeks, an indication that complements lifestyle modifications in people with borderline readings.
In functional palpitations and benign supraventricular arrhythmias associated with stress or anxiety, hawthorn is traditionally prescribed with favorable subjective effects in many patients; the clinical data are less solid than for heart failure but consistent with a mild modulating effect on atrioventricular conduction.
The doses studied in heart failure are 900 milligrams per day of the standardized extract WS 1442 (equivalent to 18-22 percent oligomeric procyanidins), divided into 2-3 doses with meals; for hypertension, 500-1,200 milligrams per day; the effect appears gradually and requires at least 6-12 weeks for clinical evaluation; non-standardized products may have highly variable efficacy.
Generally well tolerated at the doses studied; the adverse effects described are rare and mild (digestive discomfort, headache, transient palpitations); people with advanced or decompensated heart failure should use it only under cardiology supervision as an adjunct, never as a substitute for standard drug treatment (ACE inhibitors, beta-blockers, diuretics, spironolactone); those taking digoxin should be cautious because of a theoretical pharmacodynamic interaction (potentiation of the inotropic effect); in hypertension, monitoring is advisable if it is combined with antihypertensive drugs; in pregnancy and breastfeeding the data are limited and its use is discouraged as a precaution.
Information, not medical advice. Scientific evidence reflects the quality of the studies.