What is quina amarga?
Quina amarga is the wood and bark of Quassia amara, a small tree of tropical Latin America. It is one of the most bitter plants known. People have long taken it as a bitter tonic for poor appetite and an upset stomach.
It is also sold as bitterwood or amargo. Today the wood flavours bitter drinks, and extracts go into some head lice lotions and garden insect sprays.
Human evidence is thin. Long and wide traditional use is not proof that it works, and it is not proof that it is safe. One small trial supports a lice lotion; most other uses rest on tradition, lab tests and animal work.
How does quina amarga work?
The bitter taste is the main proposed mechanism. Bitter compounds on the tongue may trigger saliva and stomach juices. In people, this "bitter tonic" effect is still poorly tested.
In lab tests and animal studies, extracts slow some parasites and insects. The bitter compounds appear to act as stomach poisons to lice and larvae. Whether a drink made from the wood does the same inside your gut is not established.
In test tubes, extracts also act against malaria parasites and some bacteria. That is a long way from treating an infection in a person.
In animals, extracts have lowered blood sugar. In male animals, high doses lowered sperm counts and testosterone. Neither finding has been tested properly in people, and the second is a reason for real caution.
What forms does quina amarga come in?
Quina amarga is sold in a few simple forms.
- Dried wood chips or shavings, soaked in water to make a bitter drink.
- Powdered wood or bark in capsules.
- Alcohol tinctures and drops, often sold as digestive bitters.
- Bitter aperitifs and tonic drinks, where it is only a flavouring.
- Scalp lotions for head lice, sold mainly in Central America.
- Garden and animal insect sprays, which are never meant to be swallowed.
Strength is not standard across these forms. A home-made soak and a measured tincture are not the same thing.
Many products mix it with other bitters, such as gentian or angostura bark. Read the label for everything in the bottle.
Where it comes from:
Quassia amara was used across Suriname, Guyana, the Caribbean and Central America. Healers gave the bitter wood for weak appetite, slow digestion and fevers.
The plant carries the name of Graman Quassi, an 18th-century healer in Suriname. He is credited with bringing the remedy to European notice.
The wood entered European pharmacy lists in the 1700s as a bitter tonic. Carved "bitter cups" were sold for home use. Water left standing in the cup turned bitter, and people drank it as a tonic.
It was also given as an enema for threadworms in children, and used as a fly poison. Those are historical practices, recorded here as history, not as advice.
Who should avoid quina amarga?
- Never use quina amarga if you are pregnant or might be pregnant.
- Do not use it if you are breastfeeding.
- Do not give it to a child by mouth, and never as an enema (fluid put into the bowel).
- Do not use it if you or your partner are trying to conceive, or are in fertility treatment.
- Do not use it if you have a peptic ulcer (a sore in the stomach lining) or gastritis (an inflamed stomach lining).
- Do not use it if you have inflammatory bowel disease (long-term gut inflammation), such as Crohn's disease or ulcerative colitis.
- Avoid it if you take warfarin or any other blood thinner, unless your doctor agrees.
- Avoid it if you take insulin or other diabetes medicine, unless your doctor is checking your blood sugar.
- Avoid it if you take digoxin or another heart rhythm medicine, unless your doctor agrees.
- Do not use it if you have liver disease, unless your doctor says it is fine.
- Never swallow garden or animal insect products made from quassia.
- Never use it to treat malaria, or a fever after travel in a malaria area. Get urgent medical care instead.
When should you see a doctor?
Stop taking it and see a doctor if you get repeated vomiting, bad stomach pain, or burning that does not settle.
Get medical help the same day for any of these:
- Black or tarry stools, or blood in vomit or stools.
- Unusual bruising or bleeding that will not stop.
- Yellow skin or eyes (jaundice), or dark urine.
- Shaking, sweating, or confusion, which can mean low blood sugar.
- A spreading rash, or swelling of the face, lips or throat.
Call emergency services for fever with chills after tropical travel, or for any swelling of the throat or trouble breathing.
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