Hawthorn for heart failure: what trials show and what to know

Hawthorn refers to Crataegus species, shrubs and small trees whose berries, leaves and flowers are used to make extracts. The trial authors note that Crataegus monogyna has been used for cardiac and circulatory disorders since the first century AD, and that laboratory work has suggested properties that might be helpful in heart failure, such as effects on blood flow and antioxidant activity.

Heart failure is when the heart cannot pump blood properly, according to the NHS, which stresses that it does not mean the heart has stopped working. There is no cure, but treatment and lifestyle changes can help. Because the condition is serious and often progressive, any claim that a supplement can treat it deserves careful scrutiny.

Earlier trials reported modest improvements in exercise capacity and symptoms, but the authors of the HERB CHF trial point out that these studies were limited by short duration, unclear severity of patients and frequent lack of modern conventional treatment alongside the herbal product.

The HERB CHF trial, run at the University of Michigan, addressed this. It was a randomised, double-blind, placebo-controlled trial in 120 ambulatory adults with NYHA class II to III chronic heart failure, all of whom received conventional medical therapy as tolerated. Participants took hawthorn 450 mg twice daily or placebo for 6 months. The primary outcome was change in 6-minute walk distance.

There were no significant differences between groups in walk distance, quality of life, functional capacity, hormone levels or measures of inflammation. A modest difference in left ventricular ejection fraction favoured hawthorn, but significantly more adverse events were reported in the hawthorn group, although most were not cardiac. The authors concluded that hawthorn provides no symptomatic or functional benefit when given with standard medical therapy to patients with heart failure.

This is a single US trial of one standardised extract, and it is not a UK source. It is nonetheless a well-designed test of the question most people ask, which is whether hawthorn adds anything to the medicines they already take.

The NHS says treatment depends on the type and stage of heart failure and your overall health. Medicines include diuretics to reduce fluid build-up, such as furosemide, medicines that widen blood vessels such as candesartan or enalapril, and beta blockers to slow the heart. Surgery may be needed to restore blood flow, repair or replace valves, or fit a pacemaker or implantable cardioverter defibrillator, and in severe cases devices or a heart transplant may be considered.

Everyone diagnosed with heart failure should be offered cardiac rehabilitation, which can include exercise advice, lifestyle support and peer groups. These are the measures that are known to help, and they need regular monitoring by a clinician.

The NHS says that herbal medicines should not be taken if you are pregnant or breastfeeding, have kidney or liver problems or are taking certain medicines. It lists statins, antidepressants, diabetes medicines, blood pressure medicines such as ramipril, blood thinners such as warfarin and hormonal contraception as examples that do not mix well with herbal medicines. People with heart failure usually take several of these, so a pharmacist check is essential.

In the UK, herbal products can be sold as traditional herbal medicines with a THR registration. The MHRA guidance explains that these are based on evidence of traditional use over a period of 15 years rather than proof from modern clinical trials. A THR mark therefore says a product meets quality and safety standards and has a history of traditional use, not that it treats heart failure.

The NHS advises seeing a GP if you think you have symptoms of heart failure. It says to ask for an urgent GP appointment or call NHS 111 if you feel breathless when lying down or from everyday activity, are coughing up frothy pink phlegm or have suddenly gained weight. Call 999 for severe difficulty breathing, pale, blue or grey lips or skin, or if someone has passed out and is not responding normally.

If you already have heart failure, do not stop or change any prescribed medicine to try a supplement, and tell your heart failure team about anything you take.