The uses, pharmacology, clinical efficacy, dosage and administration, adverse effects, and drug interactions of hawthorn are discussed. Hawthorn (Crataegus oxyacantha) is a fruit-bearing shrub with a long history as a medicinal substance. Uses have included the treatment of digestive ailments, dyspnea, kidney stones, and cardiovascular disorders. Today, hawthorn is used primarily for various cardiovascular conditions. The cardiovascular effects are believed to be the result of positive inotropic activity, ability to increase the integrity of the blood vessel wall and improve coronary blood flow, and positive effects on oxygen utilization. Flavonoids are postulated to account for these effects. Hawthorn has shown promise in the treatment of New York Heart Association (NYHA) functional class II congestive heart failure (CHF) in both uncontrolled and controlled clinical trials. There are also suggestions of a beneficial effect on blood lipids. Trials to establish an antiarrhythmic effect in humans have not been conducted. The recommended daily dose of hawthorn is 160-900 mg of a native water-ethanol extract of the leaves or flowers (equivalent to 30-169 mg of epicatechin or 3.5-19.8 mg of flavonoids) administered in two or three doses. At therapeutic dosages, hawthorn may cause a mild rash, headache, sweating, dizziness, palpitations, sleepiness, agitation, and gastrointestinal symptoms. Hawthorn may interact with vasodilating medications and may potentiate or inhibit the actions of drugs used for heart failure, hypertension, angina, and arrhythmias. The limited data about hawthorn suggest that it may be useful in the treatment of NYHA functional class II CHF.
