Clinical trials have shown that standardized extracts made from the leaves and flowers of hawthorn are effective in helping people with early-stage CHF.^10,11,12 Hawthorn extracts appear to increase blood flow to the heart, increase the strength of heart contractions, reduce resistance to blood flow in the extremities, and act as an antioxidant.^13,14,15 In a large preliminary trial, people with mild to moderate CHF were given 300 mg of hawthorn flower and leaf extract (standardized to contain 2.2% flavonoids) three times a day for two months.¹⁶ Symptoms of CHF—including heart palpitations, chest pressure, and swelling in the extremities—decreased throughout the trial during the use of hawthorn. The efficacy of hawthorn for the treatment of CHF has been confirmed in a double-blind trial.¹⁷

Hawthorn extracts are available in capsules or tablets standardized to either total flavonoid content (usually 2.2%) or oligomeric procyanidins (usually 18.75%). Doctors who work with herbal medicine often suggest 80–300 mg two to three times per day. Hawthorn berry products that are not standardized may be weaker, and the recommended amount is typically 4 to 6 grams per day for the whole herb, or 4–5 ml of the tincture three times per day.

Hawthorn (Crataegus species) leaf and flower extracts have been used historically to prevent and treat a range of cardiovascular ailments and have demonstrated positive effects on heart and blood vessel function in laboratory and animal research. A ten-week trial that included 36 mildly hypertensive subjects noted a promising reduction in blood pressure in those taking 500 mg of hawthorn extract daily compared with placebo but the effect did not reach statistical significance.¹⁸ Another placebo-controlled trial that included 92 participants with mildly elevated blood pressure found treatment with hawthorn lowered both systolic and diastolic blood pressure after three months.¹⁹ Supplementing with 1,200 mg of hawthorn extract daily for 16 weeks was found to reduce diastolic, but not systolic, blood pressure significantly better than placebo in a trial with 79 subjects with type 2 diabetes.²⁰ Several trials have reported small reductions in blood pressure in people with early stage congestive heart failure taking hawthorn.²¹

 

The fruit, leaves, and flowers of the hawthorn tree contain flavonoids, including oligomeric procyanidins, which may protect blood vessels from damage. A 60 mg hawthorn extract containing 18.75% oligomeric procyanidins taken three times per day improved heart function and exercise tolerance in angina patients in a small clinical trial.²²

 

Many doctors expert in herbal medicine consider hawthorn to be an effective and low-risk therapy for congestive heart failure, the main complication of cardiomyopathy. Rigorous clinical trials have now confirmed the effectiveness of hawthorn for the signs and symptoms of early-stage congestive heart failure,^{23,24,25,26,27} though hawthorn studies with cardiomyopathy patients have yet to be conducted. The clinical trials with heart-failure patients have demonstrated efficacy using 80 to 300 mg of standardized extract of hawthorn leaves and flowers two to three times per day.

 

An animal study showed that an extract of hawthorn significantly reduced the number of experimentally induced arrhythmias.²⁸ Although the use of hawthorn for arrhythmia in humans has not been studied scientifically, it traditionally has been used for this purpose.²⁹