Educational information, not medical advice — ask your doctor or midwife.
Fat-leaf basil is a bushy, strong-smelling herb in the basil family. Its botanical name is Ocimum gratissimum. In Haiti it is called gwo bazilik, and in Jamaica clove basil.
Crush a leaf and it smells of cloves. That smell comes from eugenol, the same oil found in clove buds. The plant is used both as a cooking herb and as a home tea.
In Caribbean home medicine it is used most often for colds, coughs, fever, and upset stomach. Human evidence for those uses is thin. Long traditional use is not proof that it works, and it is not proof that it is safe.
The leaf tea, in the amounts people drink at home, is usually well tolerated. The concentrated essential oil is a different thing. It is strong, it can burn the mouth and gut, and it should never be swallowed.
Most of what is known about how it acts comes from the lab, not from people.
In test tubes, the leaf oil slows the growth of several bacteria and fungi. Whether that happens on your skin or inside your body is not established.
Eugenol and thymol, two parts of the oil, calm signs of inflammation in cell and animal studies. No good human studies confirm this.
In animals, leaf extracts lowered blood sugar and relaxed gut muscle. These results have not been repeated in people.
Some of the comfort people report may be simpler. A hot drink and its steam can ease a stuffy nose and a dry throat for a short while. That effect is real, but it is not special to this plant.
You will meet it most often as plain fresh or dried leaf.
Common forms:
Fresh leaves, used in cooking and crushed into hot water.
Dried leaf, sold loose or in tea bags.
Bush bath or steam, where leaves are steeped and the water is used to wash or to breathe over.
Poultice, where bruised leaves are laid on the skin.
Essential oil, a very concentrated distilled product sold for scent and for diluted skin use.
Mouth rinses and gels made with the oil, used in a few small dental studies.
Capsules and tinctures exist but are far less common. Strength is rarely stated in a useful way. The essential oil is the one form that carries real risk, and it is not a food.
Caribbean bush medicine has used this herb for generations. It arrived with plants and people from West Africa, where related basils were long used the same way.
Healers in Haiti, Jamaica, Trinidad and the wider region used the leaf tea for colds, fever, cough and belly pain. Leaf baths were used after childbirth and for skin trouble. Crushed leaves were rubbed on insect bites.
It also kept a place in the kitchen and the yard. Many homes grew it by the door for both cooking and tea. Records of this use are mostly from the nineteenth and twentieth centuries, and from living practice today.
Stop using it and see a doctor if any of these happen.
A fever lasts more than three days, or goes above 39C (102F).
A cough lasts more than two weeks, or you cough up blood.
Belly pain is severe, or pain sits under your right ribs.
Your skin or the whites of your eyes turn yellow.
You get a rash, swelling of the lips or face, or trouble breathing.
You bruise or bleed more easily than usual.
Go to an emergency department at once if a child swallows the essential oil. Take the bottle with you.
In the United States, the United Kingdom, Canada and the European Union it is sold as an ordinary food herb and as a supplement. No medicine agency has approved it to treat any illness. The essential oil is regulated as a flavouring and fragrance, not as a medicine to swallow.
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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