Educational information, not medical advice — ask your doctor or midwife.
Exostema caribaeum is a small tree of the Caribbean and Central America. Healers used its bitter bark for fevers. It is also called Caribbean princewood, false quina or copalchi.
The bark was once sold as a cheap stand-in for cinchona bark. Cinchona is the source of quinine, the old malaria drug. Exostema bark, though, holds no quinine at all.
Today it shows up mainly in Mexican and Central American folk use. People use it for fever, for weak digestion, and for blood sugar.
Long use in a tradition is not proof that a remedy works. It is also not proof that it is safe.
Here is the honest verdict. There are no good human trials of this bark. No use of it is proven, and the safety record in people is close to blank.
No one has shown how this bark acts in the human body. The work that exists is in test tubes and in rodents.
The bark holds coumarins, a group of plant compounds. In rats and mice, bark extracts have lowered blood sugar in some studies. Whether the same thing happens in people is not known.
In lab dishes, extracts of several "quina" barks slow malaria parasites. The effect reported was weak. That does not make the bark a malaria treatment.
One point matters more than any lab finding. The bark contains no quinine, so it cannot work the way quinine does. Its old reputation as a quinine substitute rested on taste and price, not on chemistry.
Bitter plants in general can prompt saliva and stomach juices. That is a known effect of bitter taste. It has not been tested for this particular bark.
You will mostly meet it as raw bark, if you meet it at all. It is uncommon outside Mexico and Central America.
Forms in use:
- Dried bark chips or powder, sold loose in herb markets - A bark tea, made by boiling the bark in water - Tinctures (alcohol extracts), from a few specialist suppliers - Capsules, rarely
There is a real naming problem here. The market name "copalchi" is used for several unrelated barks. Hintonia latiflora and some Croton species are sold under the same name.
That means a bag labelled copalchi may not be this plant. Buy only from a seller who prints the full botanical name.
Spanish colonial doctors took the bark up in the 1700s. Cinchona was costly, and this bark was bitter and local. It was shipped to Europe as a cheap fever remedy.
It appeared in some old pharmacopoeias (official drug lists) under names such as Caribbean bark or Jamaica bark.
In Mexico and Central America, healers boiled the bark for fever and chills. Later folk practice added "sugar sickness", which we now call diabetes.
Medical use faded once pure quinine became cheap and widely sold. The bark stayed in regional folk practice, where it remains today.
Stop using it and get medical help if any of these happen.
- Shaking, sweating, hunger or confusion; these can mean low blood sugar - A fever above 39C, or any fever lasting more than two days - Any fever after travel to a malaria area; get seen the same day - Yellow skin or eyes, or dark urine - Lasting vomiting or diarrhoea
Call emergency services for swelling of the lips or tongue, trouble breathing, or fainting.
In the United States it may be sold as a herbal product, and the FDA has not approved it to treat any disease. In the UK and the European Union it is not a licensed herbal medicine. In Mexico and parts of Central America it is sold openly as a traditional market herb.
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.
One email with the summary. We'll also send a short weekly evidence update — unsubscribe any time.
