About Herbs

Bottom Line: Hawthorn has been shown to improve heart function, shortness of breath, palpitations, and exercise tolerance in people with heart failure. There is no evidence to support any other effects.

Hawthorn is a fruit extract that has been used as an digestive aid in traditional Chinese medicine for centuries. Scientists think that hawthorn extract causes dilation of the smooth muscle that lines coronary arteries, thereby increasing blood flow to the heart. Hawthorn is also thought to increase heart muscle contraction, heart rate, nerve transmission, and heart muscle irritability.

Heart disease:
Several clinical trials conducted in Europe have tested the use of hawthorn for treating ischemic or hypertensive heart disease. Only a few clinical trials have been performed in the United States.

One clinical trial in patients in New York's Heart Association functional class II or III found that the group taking hawthorn had significant improvements in edema, shortness of breath, and palpitations compared to patients taking a placebo. No differences in electrocardiograms were found between groups. No side effects were reported.

A similar clinical trial gave 30 mg of hawthorn extract to 45 patients, and a placebo pill to 35 others. The group taking hawthorn reported a greater overall improvement of cardiac function, shortness of breath, and palpitations, but no difference in electrocardiogram, compared to the placebo group. Nausea, fatigue, and sweating were reported side effects of hawthorn.

Seventy-eight patients with New York's Heart Association functional class II were given 600 mg of hawthorn daily or a placebo pill. After eight weeks, the exercise tolerance (as measured on a stationary bicycle) was greater in the group taking hawthorn than the placebo group. Patients taking hawthorn also had a significant decrease in systolic blood pressure and heart rate.

May flower, quickthorn, whitehorn

Derived from the flower, leaves, and fruits of the plant. Hawthorn has been used as an digestive aid in traditional Chinese medicine for centuries. But currently, it is used primarily to treat heart failure ⁽¹⁰⁾. Placebo controlled clinical studies suggest significant improvement in cardiac function, dyspnea, palpitations for patients with ischemic or hypertensive heart diseases, and for patients with diabetes ⁽¹³⁾. Conclusions from a meta analysis also indicate that hawthorn may benefit patients with chronic heart failure ⁽¹⁴⁾.
Frequently reported adverse events include nausea, sweating, and fatigue. Signs of overdose include hypotension and arrhythmias. An initial reduction in digoxin dose may be required if used concomitantly with hawthorn. Other drug interactions include enhanced response to CNS depressants and anti-hypertensive agents ⁽⁸⁾.

It is thought that hawthorn causes direct dilation of smooth muscle in coronary vessels thereby lowering their resistance and increasing blood flow. Hawthorn is also characterized as having positive inotropic effects leading to an increase in heart rate, nerve conductivity, and heart muscle irritability.

Should not be taken by women who are pregnant or breast-feeding.

Common: Nausea, fatigue, sedation, and sweating
Toxicity: Hypotension, arrhythmia
⁽⁷⁾

Digoxin: Hawthorn enhances the action of digoxin. The dose of digoxin may need to be lowered if hawthorn is added. Conversely, an increase in digoxin dose may be required if hawthorn is discontinued.
Hypertensives: Hawthorn may potentiate activity.
Antiarrhythmics: Hawthorn may potentiate or interfere with their activity
CNS depressants: Hawthorn may have additive effects.
⁽⁸⁾

Hawthorn has been extensively studied in Europe. Few studies to date have been performed in the US.

Werbach MR, et al. Botanical Influences on Illness: A Sourcebook of Clinical Research. Third Line Press, 1994.
A controlled, double-blind study of hawthorn versus placebo on patients with ischemic or hypertensive heart disease in New York's Heart Association functional class II or III. The hawthorn group had significant improvements in cardiac edema, dyspnea and palpitations. No differences in ECGs were seen between treatment groups. The authors did not report any adverse events.

Iwamoto M, et al. Klinische Wirkiung von Crataegutt bei Herzerkrankungen ischasemischer und/oder hypertensiver Genese. Planta Med 1981;42:1-16.
A hawthorn preparation containing 30 mg hawthorn extract, standardized to 1 mg procyanidins, was used in a double-blind controlled study of 80 patients (35 active, 45 placebo). The hawthorn group reported a greater overall improvement of cardiac function, dyspnea, and palpitations. Improvements in ECGs were not found to differ. Nausea, fatigue, and sweating were reported in the hawthorn group.

Schmidt U, et al. Efficacy of the hawthorn preparation in 78 patients with chronic congestive heart failure defined as NYHA functional class II. Phytomedicine 1994;1:17-24.
Seventy-eight patients were administered hawthorn extract 600 mg/day or a placebo. After a one-week washout, patients were treated for eight-weeks. An ergometer bicycle was used to determine working capacity at baseline and during treatment. Between day zero and fifty-six, the working capacity of those taking hawthorn increased by 28 watts compared to 5 watts in those receiving placebo. There was a significant decrease in systolic blood pressure and heart rate as compared to placebo.