Hawthorn: The Traditional Heart Herb, What the Research Says

One of the fascinating things about herbal medicine is that some plants have accompanied humanity for centuries precisely because of their real effect on the body. Hawthorn (in Latin Crataegus) is a clear example of this: a low, thorny shrub from the rose family, whose white flowers, leaves, and red fruits have been used in European folk medicine since the Middle Ages, especially as a heart herb. Across Europe, it is still prescribed in some countries as a herbal preparation for heart support, giving it a special status in the world of herbal supplements.

But this is precisely where extreme caution is needed. The heart is not an organ to be trifled with, and heart failure is a serious disease requiring close medical monitoring and treatment. The question is not just "does hawthorn work," but "what exactly does it do, in which population, and with what level of evidence," and no less importantly, "which medications does it interact with." In this article, we will separate tradition from science, review the current clinical evidence, and explain why we rated hawthorn yellow, and why the first rule regarding it is to consult a doctor.

What is Hawthorn?

Hawthorn is the name for dozens of species from the genus Crataegus, shrubs and small trees from the rose family. Medicinal preparations are primarily based on extracts from the leaves and flowers, and sometimes also from the fruits. Here is what is important to understand about it:

• The active components are flavonoids and OPCs. Hawthorn is rich in flavonoids (such as vitexin and hyperoside) and oligomeric proanthocyanidins (OPCs), a group of plant antioxidants considered responsible for most of its biological activity.
• Traditional use focuses on the heart. In European medicine, it was used to support heart function, feelings of chest pressure, and palpitations, and in some countries, it is officially defined as a herbal heart preparation.
• The most studied preparation is WS 1442. Most high-quality studies used a standardized commercial extract called WS 1442, which is important to remember when comparing products, as not all hawthorn supplements are identical in content.
• It is sold in several forms. As capsules of standardized extract, as drops, and as tea from flowers and leaves. The form and dosage vary greatly between products.

An important point for perspective: when discussing hawthorn for "heart failure," it refers to an adjunctive layer alongside medical treatment, not an independent therapy. The evidence we review pertains to hawthorn as an addition (adjunct) to standard heart medications, not as a replacement for them. This is a critical distinction that will be repeated throughout this article.

The Connection to Heart Health: The Mechanism

What makes hawthorn affect the heart? Over the years, several mechanisms have been proposed, some based on laboratory and animal studies. The central idea is that hawthorn extract combines a moderate effect on the heart muscle, blood vessels, and oxidative stress, and therefore may improve the exercise capacity of patients with mild heart failure.

First mechanism, effect on the heart muscle. In experimental models, hawthorn extracts showed a moderate positive inotropic effect (i.e., a gentle strengthening of the heart's contraction force) and a certain prolongation of the electrical recovery period of heart cells. The hypothesis is that this may contribute to better pumping efficiency in mild heart failure. It is important to emphasize: this is a mild effect, far from the potency of dedicated heart medications.

Second mechanism, vasodilation and nitric oxide. The flavonoids and OPCs in hawthorn have been studied for their ability to support the production of nitric oxide (NO) in the blood vessel wall. Nitric oxide helps relax blood vessels, and thus may contribute to a moderate reduction in peripheral resistance and improved blood flow. This is also the reason for interest in a possible, moderate effect on blood pressure.

Third mechanism, antioxidant activity. OPCs are active antioxidants that neutralize free radicals. Oxidative stress is involved in damage to the blood vessel wall and the progression of heart disease, so it has been suggested that hawthorn's contribution stems partly from antioxidant protection of heart and blood vessel tissue. However, the path from "antioxidant in a test tube" to "clinical benefit in humans" is long, and this is precisely where the studies come in.

Current Evidence

Study 1: The 2008 Cochrane Review by Guo, Pittler, and Ernst

This is the central and most cited evidence regarding hawthorn. In 2008, Guo, Pittler, and Ernst published a systematic review and meta-analysis under the Cochrane organization, titled "Hawthorn extract for treating chronic heart failure," which aggregated randomized controlled trials on the subject.

The review included 14 trials, of which 10 had sufficient data for pooled analysis, encompassing about 855 patients. The findings, when hawthorn was given as a supplement to standard heart failure treatment, were consistently positive: a significant improvement in maximal exercise workload (about 5.35 watts), an increase in total exercise tolerance (about 122.76 watt x minutes), and a beneficial decrease in the rate-pressure product (about 19.22 mmHg/min), an indirect measure of myocardial oxygen consumption. Concurrently, symptoms such as shortness of breath and fatigue also improved compared to placebo. Reported side effects were uncommon, mild, and transient (nausea, dizziness, gastrointestinal discomfort).

This is encouraging evidence, but it is important to interpret it correctly. The improvement is mainly in functional quality and exercise tolerance in mild heart failure, not proof that hawthorn prolongs life or prevents hospitalizations. The review itself referred to hawthorn as a supportive treatment, alongside medications, not in place of them.

Study 2: The SPICE Trial by Holubarsch and Colleagues

If the Cochrane review is the encouraging side, the SPICE trial is the reality check. The SPICE trial (published by Holubarsch and colleagues) was a large, international, randomized, double-blind, placebo-controlled trial that examined the effect of hawthorn extract WS 1442 on hard outcomes in heart failure patients.

The trial included 2681 patients with NYHA class II-III heart failure and reduced ejection fraction (LVEF up to 35%), who received 900 mg of hawthorn daily or placebo for about 24 months, in addition to optimal medical therapy. The result: hawthorn showed no significant effect on the primary endpoint of cardiac events (hazard ratio 0.95, not statistically significant), but was found safe for use alongside medications. In a specific subgroup (patients with less impaired heart function), a possible signal for a reduction in sudden cardiac death was seen, but this is a secondary finding requiring further confirmation and should not be relied upon.

The combined message from both studies is clear and fair: Hawthorn may improve symptoms and exercise tolerance in mild heart failure, but it is not proven to alter the disease course or prolong life. It is a possible addition, not a medication.

Study 3: Hawthorn and Blood Pressure, Limited Evidence

Another area that has attracted interest is blood pressure. Several small trials examined the effect of hawthorn extract on blood pressure, some in people with mild hypertension or diabetes, and showed a moderate reduction in diastolic blood pressure or mixed results.

Caution is even more warranted here. The studies are small, the populations are varied, and the effects are modest compared to drug therapy or lifestyle changes. Hypertension is a condition requiring medical diagnosis and monitoring, and hawthorn is not a substitute for its treatment. At best, it is a moderate and insufficiently proven addition, which may even interact with blood pressure medications, a topic we will expand on later.

What About Palpitations, Anxiety, and Other Heart Conditions?

Beyond heart failure and blood pressure, hawthorn is sometimes marketed for relieving palpitations, feelings of chest pressure, and even stress and anxiety related to the heart. The evidence for these uses is scant and primarily anecdotal or traditional, not based on large, high-quality trials. It is very important to understand: palpitations, chest pain, or arrhythmia are symptoms that can indicate a cardiac condition requiring urgent medical evaluation, not something to start treating on your own with a herbal supplement.

Another critical point is what hawthorn is not. It is not intended for cardiac emergencies, does not treat heart attacks, and is not a substitute for life-saving medications like blood thinners, beta-blockers, or heart failure drugs. A person with known heart disease who feels hawthorn is "enough for them" and stops their medications is putting themselves at real risk. The bottom line is the same throughout this article: hawthorn is, at best, a cautious supporting player within a medical treatment framework, never a replacement for it.

Should You Start Taking Hawthorn?

This is precisely why we rated hawthorn yellow, with a heavy emphasis on caution. On one hand, there is real evidence for symptom improvement in mild heart failure as a supplement; on the other hand, this involves heart disease, a sensitive population, and a plant that interacts with major heart medications. Here are the considerations:

• Interactions with medications, the most important point. Hawthorn may potentiate the effect of heart and blood pressure medications, thereby creating risk. It has been studied for potential interaction with digoxin (a heart medication), beta-blockers, nitrates, and blood pressure-lowering drugs. Uncontrolled combination could cause a dangerous drop in blood pressure or unwanted cardiac effects. Therefore, it is mandatory to inform your doctor before any combination.
• Heart disease requires a doctor. Anyone with heart failure, hypertension, arrhythmia, or any heart disease must consult their cardiologist or primary care physician before taking hawthorn. Do not replace any medication with hawthorn.
• The benefit is moderate and limited in scope. The proven improvement is mainly in exercise tolerance and symptoms in mild heart failure, not in mortality or hard outcomes. It is not a solution.
• Mild side effects. In most studies, side effects were rare and mild (nausea, dizziness, gastrointestinal discomfort), but this does not negate the issue of drug interactions, which is the primary concern.

Additionally, certain groups need special caution. Pregnant or breastfeeding women should avoid hawthorn due to a lack of sufficient safety data. Anyone scheduled for surgery should inform the medical team due to the possible effect on blood pressure and the heart. And of course, anyone regularly taking heart or blood pressure medications must not start hawthorn without a doctor's approval. As always: the absence of a dramatic warning on a label does not mean the supplement is safe for everyone, especially when it comes to the heart.

What Should You Take Away from the Research?

1. If you have any heart disease, talk to your doctor first. This is not a ceremonial statement. Hawthorn interacts with heart and blood pressure medications, and heart failure requires medical monitoring. The doctor will determine if hawthorn has a place in addition to your treatment, and never in place of it.
2. Do not replace any medication with hawthorn. If you are taking blood thinners, beta-blockers, digoxin, nitrates, or blood pressure medications, do not stop or replace them. Hawthorn is, at most, an addition, if at all, under medical supervision.
3. If you are healthy, focus on the fundamentals. Heart health is built primarily from regular physical activity, a Mediterranean diet, good sleep, smoking cessation, and control of blood pressure and cholesterol. These have a much greater impact than any herbal supplement.
4. Choose a standardized extract if you do proceed. If a doctor approves, prefer a standardized, high-quality preparation (like the WS 1442 extract that was studied), as the content of active ingredients varies greatly between products.
5. Do not ignore cardiac symptoms. Palpitations, chest pain, or shortness of breath are not things to treat with a supplement; they are symptoms requiring medical evaluation.

For those whose doctor has approved trying hawthorn from a reliable source, you can purchase Hawthorn on iHerb and choose a standardized extract from a brand with quality control. But remember: when it comes to the heart, consulting a doctor is far more important than choosing a brand. To check which supplements are truly suitable for your health goals, including heart health, based on your age and condition, you can use our personal supplement checker which rates each supplement according to the quality of evidence.

The Broader Perspective

Hawthorn is an excellent example of a plant that has both a long tradition and considerable scientific evidence behind it, yet still requires extreme caution. On one hand, the Cochrane review showed that as a supplement to standard care, it improves exercise tolerance and symptoms in mild heart failure. On the other hand, the large SPICE trial taught us that it has no proven effect on hard outcomes like mortality, and the most critical factor is its interaction with heart medications. This is a classic profile of a yellow supplement in a particularly sensitive condition: some evidence, but a medical context that requires supervision.

The practical lesson is twofold. First, when it comes to the heart, the difference between a "supplement" and a "medication" is a matter of life and death. Hawthorn is not a substitute for medical treatment, is not suitable for self-treating heart disease, and must not be started without involving your doctor. Second, it is important to remember that even the most "cardiac" herb in history does not compete with the fundamentals that build a healthy heart over the years. Heart health and longevity rely on diet, physical activity, sleep, smoking cessation, and control of blood pressure and lipids, and hawthorn can be, at best and under supervision, a cautious secondary contributor. And that is precisely the perspective we hold here: to rate each supplement according to what the science truly shows, when it is promising, and when, as in the case of the heart, caution is paramount.

References:
Guo R., Pittler M.H., Ernst E., Hawthorn extract for treating chronic heart failure, Cochrane Database of Systematic Reviews, 2008, Issue 1, CD005312 (DOI: 10.1002/14651858.CD005312.pub2)
Holubarsch C.J.F. et al., The efficacy and safety of Crataegus extract WS 1442 in patients with heart failure: the SPICE trial, European Journal of Heart Failure, 2008;10(12):1255-1263 (DOI: 10.1016/j.ejheart.2008.10.004)