Educational information, not medical advice — ask your doctor or midwife.
Logwood is the dark heartwood of a small thorny tree from Central America. It is best known as a dye that gives deep red and purple colours. In folk medicine the wood was boiled into a bitter, astringent (tightening) drink for loose bowels.
The tree grows wild in Mexico, Belize, Guatemala and Honduras. Spanish and British traders shipped the wood to Europe for centuries. Labs still use a dye made from it to stain tissue slides.
Here is the honest verdict on the medicine side. There are no good human trials of logwood for any health problem. Long traditional use is not proof that it works, and it is not proof that it is safe.
The short answer is that nobody has shown how it works in people.
The wood is rich in tannins. In test tubes, tannins bind to proteins and make surface tissue contract. That is the usual reason given for the old use in diarrhoea, but it has not been tested properly in people.
Logwood also holds haematoxylin, which turns into a pigment called haematein in air. In laboratory tests, haematein mops up free radicals and slows the growth of some bacteria. Whether any of this happens in the human gut is unknown.
Some animal work suggests extracts may lower blood sugar or calm swelling. These are early signals in rodents, not findings you can count on. No dose, no form and no safe limit for people follows from them.
Most logwood on sale today is not a health product. Common forms include:
- Wood chips, shavings or sawdust for dyeing cloth. - Liquid or powdered dye extract for textiles.
- Haematoxylin stain for laboratory use, often mixed with other chemicals. - Occasional folk preparations: a boiled wood decoction or a tincture.
Lab stains and textile dyes are not food grade. They may carry mordants such as alum or metal salts. Do not treat them as something to swallow.
Logwood was a prized trade good long before it was a remedy. Maya and other peoples of the region used the heartwood as a dye. European traders fought over the logwood coast of Central America in the 1600s and 1700s.
Regional folk healers boiled the wood for diarrhoea, dysentery and bleeding gums. Entries for logwood extract appeared in British and American pharmacopoeias in the 1800s, mostly as a bowel astringent. It faded from medical use in the 1900s.
That record tells you the plant was familiar and widely traded. It does not tell you that the old uses were ever checked.
Stop and see a doctor if diarrhoea lasts more than two days, or sooner in a child or an older adult.
Get urgent care for any of these:
- Blood or black colour in the stool. - Fever with stomach pain. - Signs of fluid loss: dizziness, dry mouth, little or no urine. - Vomiting that stops you keeping fluids down. - Yellow skin or eyes, which can signal a liver problem.
Red urine after logwood may just be the dye. Do not assume that; have it checked.
Logwood is sold worldwide as a dye and as a laboratory stain, not as a licensed medicine. It is not approved as a food colour in the United States or the European Union. If a seller markets it as a supplement in the US, it falls under dietary supplement rules, which do not require proof that it works.
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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