Educational information, not medical advice — ask your doctor or midwife.
Bay geranium is a low, spreading beach shrub used as a home remedy in the Caribbean. Its botanical name is Ambrosia hispida. In the Bahamas and the Turks and Caicos it is often called fever bush or sea geranium.
It grows on sand, dunes and rocky shores. The grey-green leaves are deeply cut and smell sharp when crushed. The leaves and flowering tops are the parts people use.
The plant belongs to the ragweed group, in the daisy family. That family link matters, because these plants set off allergy and skin rash in some people.
Here is the honest verdict. We found no human trials of bay geranium for any health problem. Long use in Caribbean bush medicine is not proof that it works, and it is not proof that it is safe.
No one has shown how bay geranium works in the human body.
Tradition held that a hot cup of the tea brings on sweat and breaks a fever. That idea has never been tested in a trial.
Plants in the Ambrosia group make bitter compounds called sesquiterpene lactones. In test tubes, some of these slow bacteria and damp down signs of inflammation. Whether that happens in a person who drinks the tea is not known.
In lab and animal work, extracts of some Ambrosia species have acted against malaria parasites and other microbes. This work was done on plant extracts in dishes and in animals. It does not tell you what a cup of tea will do.
The same bitter compounds have another, better proven effect. They can irritate skin and trigger allergic reactions in ragweed-sensitive people. That is well recorded for this plant family.
Bay geranium also carries a strong-smelling oil. A warm, aromatic drink can feel comforting when you are unwell. Feeling better for a short while is not the same as treating an infection.
Bay geranium is mainly a home remedy, not a packaged product.
The usual forms are:
- Fresh leafy stems, picked from the coast.
- Dried leaf and flowering tops, sold in Caribbean markets.
- A boiled tea, by far the most common use.
- A cooled wash or bush bath for skin.
- Crushed fresh leaves laid on the skin as a poultice.
You will rarely find capsules, tinctures or standard extracts. The plant is not a common supplement outside the region.
Because there is no agreed strength, home teas vary from cup to cup. A weak brew and a strong brew can look much the same.
Bay geranium has a long place in Caribbean bush medicine.
Coastal communities in the Bahamas, the Turks and Caicos and the Eastern Caribbean gathered it from dunes and beach edges. The common name fever bush came from its main traditional use.
Healers and households boiled the leaves for fevers, colds and chills. Some families used the tea for period pain or an upset stomach. Others used a cooled wash for itchy skin and sores.
Surveys of local plant use in the twentieth century recorded it again and again. It also appeared in market stalls and in bush bath mixtures.
These records tell us what people did and why. They do not tell us whether the plant helped. Past use is a reason to study a plant, not a reason to treat yourself with it.
Stop and get medical help straight away if you have swelling of the lips, tongue or throat, a spreading rash, or wheeze and trouble breathing. These can be signs of a severe allergic reaction.
See a doctor the same day for a fever above 39C (102F), a fever lasting more than three days, or fever with a stiff neck, confusion or a rash that does not fade when pressed.
In dengue and malaria areas, get urgent care for severe belly pain, bleeding gums, vomiting blood or black stools.
Stop using it and speak to a doctor if you get a skin rash, itching, or stomach pain that does not settle.
Always see a doctor first for a fever in a baby, a young child, a pregnant person, or anyone with a weak immune system.
Bay geranium is not approved as a medicine in the United States, the United Kingdom or the European Union. In the Bahamas, the Turks and Caicos and nearby islands it is gathered and sold as a traditional bush medicine.
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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