Educational information, not medical advice — ask your doctor or midwife.
Sweet woodruff is a small, shade-loving woodland plant from Europe. In French it is called aspérule odorante, in German Waldmeister. The dried leaves smell strongly of fresh hay and vanilla.
That scent comes from coumarin, which forms as the plant wilts and dries. European folk use centred on calming teas, headaches, tired legs, and flavouring May wine. The herb is still used today mostly as a flavouring, not as a medicine.
Human evidence for any health claim is very thin. No good trials have tested the herb in people. Long tradition is not proof that something works, and it is not proof that it is safe.
Coumarin is the reason this page carries real cautions. In large amounts it can upset the liver in some people. That matters more than any benefit the plant has been credited with.
Nobody has shown in people how sweet woodruff works, or that it works at all.
The calming claims are usually pinned on coumarin. In animal work, coumarin and related plant compounds can cause drowsiness at high doses. Whether a cup of tea does anything to a person's sleep has not been tested.
The plant also holds iridoid compounds such as asperuloside. In test-tube and animal studies these show mild anti-inflammatory activity. That is a long way from showing that a tea eases sore legs or a headache.
One myth is worth clearing up. Coumarin by itself is not a blood thinner (anticoagulant), and sweet woodruff is not warfarin. The drug-like, bleeding-causing compound is dicoumarol, which forms when plant material goes mouldy.
That is why damp or musty stored herb is treated as unsafe, while fresh dried herb is not. Even so, doctors usually still ask people on blood thinners to steer clear, because the data are so thin.
The liver effects of coumarin are better understood. In a small share of people, steady coumarin intake raises liver enzymes in blood tests. This has been seen with the isolated compound at medicine-level doses, not with casual tea drinking.
Most people meet sweet woodruff as a flavour rather than a remedy.
Common forms include:
- Dried loose herb for tea or infusion - Sprigs steeped in white wine to make May wine (Maibowle) - Syrups, jellies and sweets labelled Waldmeister - Scented sachets, potpourri and linen bags - Tinctures and herbal blends, sold by some suppliers - Homeopathic preparations, which contain little or no plant material
Many bright green Waldmeister syrups and ice creams use artificial flavour, not the plant. Check the label if that matters to you.
Scented sachets and potpourri are for the air and the cupboard. They are not meant to be eaten or brewed.
Sweet woodruff has a long, well-documented place in European folk practice.
In the Middle Ages it was strewn on floors and packed into mattresses for its smell. Monastery and household records describe it hung in rooms to freshen the air. It was also used against moths in stored linen.
May wine is its best-known use. Wilted sprigs were steeped in white wine for spring festivals in German-speaking lands. The custom is still kept in some regions today.
Herbal writers credited the plant with calming nerves, easing headache and helping heavy legs. Some older texts called it a blood cleanser, a vague idea that has no modern meaning. Compresses of the crushed herb were laid on bruises and small wounds.
German regulators later reviewed the herb and did not approve it for medical use. They pointed to weak evidence and to headaches reported after larger doses. Food rules in several countries now limit how much coumarin a product may carry.
Stop using it and see a doctor promptly if you notice:
- Yellow skin or yellow eyes - Dark urine or pale stools - Pain under your right ribs - Nausea or vomiting that will not settle - Unusual tiredness with loss of appetite - A headache that is severe or will not go
Seek urgent care for unusual bruising or bleeding that will not stop, or for a rash with swollen lips, face or tongue and trouble breathing.
Tell any doctor who checks your liver blood tests that you have been using this herb.
In the European Union, sweet woodruff may be used in food and drink, but coumarin levels are capped by flavouring law. German authorities reviewed the herb for medical use and did not approve it.
In the United States, the Food and Drug Administration bans coumarin as a food additive. Sweet woodruff is permitted there only in alcoholic beverages.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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