Educational information, not medical advice — ask your doctor or midwife.
Assa-peixe is a tall Brazilian shrub whose leaves and flower tops are brewed as a tea. It is used in folk practice mostly for coughs, chest colds and blocked airways.
Its botanical name is Vernonia polyanthes. Many botanists now file it as Vernonanthura polyanthes. It belongs to the daisy family, alongside chamomile and marigold.
The plant grows fast on roadsides and old pasture across much of Brazil. Bees work its white flower spikes, and the dark honey from them is sold under the same name.
Here is the honest verdict. There are no good human trials of assa-peixe for any use. Almost everything known comes from lab dishes and rodent studies.
Long traditional use tells you that people valued the plant. It does not tell you that the plant works, and it does not tell you that it is safe. That holds for every section below.
This page does not tell you to take it. It sets out what the tradition claimed, what the research actually shows, and who should stay away.
No one has shown how assa-peixe acts in the human body. The proposed mechanisms below all come from animals or test tubes.
In rats, leaf extracts lowered blood pressure. In isolated blood vessel tissue, the extract appeared to relax the vessel wall. That fits the folk use for blood pressure, but rat results often fail in people.
In rodent stomach models, extracts cut the number and size of stress-induced ulcers. Researchers think this may come from more protective mucus and less acid damage. This has not been tested in human stomachs.
In mice, extracts reduced paw swelling in standard inflammation tests. Some of the plant's bitter compounds appear to damp inflammation signals in cell studies.
In test tubes, extracts slow the growth of some bacteria and fungi. Whether a cup of tea reaches those germs in your chest at a useful strength is not known.
For cough itself, there is no clear mechanism at all. The warm fluid and steam of any tea can loosen mucus and soothe a sore throat. That effect is not special to this plant.
Most people meet assa-peixe as a loose dried leaf tea. Other forms show up in Brazilian markets and herbal shops.
- Dried leaves and flower tops, loose or in tea bags, brewed as a hot tea. - Homemade syrups, where the tea is cooked down with sugar or honey for cough. - Alcohol tinctures and fluid extracts, sold in dropper bottles.
- Assa-peixe honey, a food made by bees from the flowers. - Washes and poultices of the cooled tea, used on the skin in folk practice. - Occasional capsules of dried leaf powder.
The honey is a food, not a drug. It carries honey's own rule. Never give honey to a baby under one year.
There is no standard strength for any of these. Two packs of the same tea can differ a lot. Tinctures are far more concentrated than tea, so the forms are not swapped one for one.
Assa-peixe has a long place in Brazilian country medicine. Rural and caboclo healers brewed the leaf for cough, chest colds, flu and hoarse voice.
The name is often read as "roast fish", from the old habit of using the dried stems as quick cooking fuel. The plant was treated as a useful weed: fuel, bee forage and home remedy.
Healers also used the cooled tea on wounds, boils and bruises. Some traditions gave it for stomach pain, fever and high blood pressure.
The plant appears in Brazilian lists of medicinal plants used in public health programmes. That listing reflects traditional use and local availability. It is not a finding that the plant treats disease.
Similar uses are recorded in other parts of Latin America where Vernonia species grow. None of this history was built on controlled trials.
Stop taking it and see a doctor if any of these happen.
- You get a rash, swollen lips or face, or any trouble breathing. Swelling or breathing trouble is an emergency; call emergency services. - You feel dizzy, faint or unusually weak, which can mean your blood pressure has dropped too low. - You have stomach pain, vomiting, dark urine or yellow skin or eyes.
Also see a doctor if your cough lasts more than two weeks, brings up blood, or comes with fever, chest pain or breathlessness. Those need a diagnosis, not a tea.
In Brazil, assa-peixe is sold as a traditional herbal tea and appears on national lists of medicinal plants used in public health. That listing reflects traditional use, not proof of benefit. In the United States, the United Kingdom and the European Union it is not approved as a medicine; it may appear as a herbal product or imported tea, and no health claims are authorised.
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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