Rosaceae

Crataegus monogyna

Hawthorn · May · Whitethorn

Trial support Caution

Part used: leafflowerfruit
Native range: Europe, north Africa and western Asia; naturalised and invasive in Australia and New Zealand
Morphology: A thorny deciduous tree to ten metres with deeply lobed leaves, dense heads of white flowers with a heavy scent, and dark red haws each containing a single stone.

What is in it

oligomeric proanthocyanidins

flavonoids vitexin, hyperoside

triterpene acids

Evidence

Among the better-evidenced entries here. A Cochrane review of hawthorn extract as an adjunct in chronic heart failure found improvement in exercise tolerance and symptoms. A later large trial in more severely ill patients found no effect on mortality. It is an adjunct with modest symptomatic benefit rather than a treatment.

Safety

Generally well tolerated; dizziness and nausea are the commonest complaints. The concern is entirely about what it is used alongside: someone treating heart failure with hawthorn instead of prescribed therapy is in danger, and the interaction profile with cardiac drugs is real.

Interactions: May potentiate digoxin; Additive with antihypertensives and nitrates

Regulatory: Permitted as a listed ingredient; a registered medicine in Germany.

How the traditions classify it

Galenic Used for the heart in European practice from the medieval period, though its cardiac reputation is largely nineteenth century onward.

Three systems, rating the same plant. Where they disagree, none of them is correcting the others — they are separate frameworks that arrived at their categories independently.

Historical use

A hedging and boundary tree of enormous folkloric weight in Britain and Ireland — bringing may blossom indoors was widely held to be unlucky, and lone hawthorns were left standing in fields as fairy trees. Its medicinal use for the heart was established by the late nineteenth century.

Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.

Worth knowing

Hawthorn is one of the few entries here where the evidence is genuinely decent and the danger is in the substitution rather than in the plant.

Chronic heart failure is a condition with effective, evidence-based, life-extending drug therapy. A herb with modest symptomatic benefit as an adjunct is a reasonable thing; the same herb used instead is a mortality risk, and the trial that looked at severely ill patients found no survival benefit at all.

Its folklore is among the densest of any European plant. Lone hawthorns were left standing in Irish fields because they were held to belong to the fairies, and road schemes have genuinely been rerouted around them within living memory. The smell has something to do with it — hawthorn blossom contains trimethylamine, one of the compounds produced by decaying flesh, which is probably why bringing it indoors was so widely thought to bring death into the house.

Nomenclature verified against GBIF backbone taxonomy.