Educational information, not medical advice — ask your doctor or midwife.
Kaffir lime (Citrus hystrix) is a small, bumpy green citrus whose fragrant leaves and peel are used in cooking and in home remedies. People use it mainly as a food flavouring, a scented oil, and a traditional hair and scalp rinse.
The honest verdict: almost all of the research is laboratory and animal work. Long traditional use tells you that people found a plant useful, but it is not proof that it treats any illness, and you should read everything below with that in mind.
In Western and European kitchens the fruit is a recent import rather than an old herbal staple. Used as a food or a diluted scent it is generally well tolerated. The concentrated essential oil is the part that needs real care, because citrus peel oils can irritate skin and make it burn more easily in sunlight.
No one has shown how kaffir lime works in the human body, because the human studies have not been done.
In test tubes, the peel and leaf oils slow the growth of some bacteria and fungi. That effect is thought to come from the oil dissolving into microbe cell walls. Whether anything similar happens on your skin or scalp at safe, diluted strengths is unknown.
The fruit juice is sour and acidic, much like other limes, which is why it has been used as a cleansing rinse. That is a simple physical effect, not a medicinal one.
Fresh or frozen leaves are the most common form. They are torn or shredded into soups and curries and are treated as a food, not a supplement.
Dried leaves and dried peel are sold for cooking and for making infusions. Drying weakens the aroma, so more is usually needed for the same flavour.
The fruit juice is very sour and is used mostly as a scalp and hair rinse, diluted with water. It is rarely drunk on its own.
Essential oil, steam-distilled from leaf or peel, is the most concentrated form. It is sold for scent and for diluted skin use, and it should never be swallowed or put on skin undiluted.
Kaffir lime comes from tropical Southeast Asia, where it has been grown for centuries in Thailand, Indonesia, Malaysia and the Philippines. Its leaves are a staple of the region's cooking and its juice has long been used as a hair and scalp wash.
It reached Western and European kitchens mainly in the late twentieth century, alongside the rise of Thai food. There is no old European herbal record for it.
Note on the name: many people now prefer makrut lime, because the older name carries a racial slur in parts of southern Africa.
Get emergency help straight away if someone swallows kaffir lime essential oil, or if the mouth, throat or chest hurts after contact with it. Also get urgent help for trouble breathing, swelling of the lips or tongue, or a spreading rash, which can mean a serious allergic reaction.
See a doctor or pharmacist within a few days if a rash, blistering or sunburn-like redness appears on skin where you used it, or if scalp itching and flaking get worse instead of better.
Book a normal appointment if you have dandruff or a scalp problem that has not improved after about four weeks, or if you take prescription medicines and want to use kaffir lime peel or oil regularly.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
Reviewed by the HealisticMD editorial team How we grade evidence →
The published evidence for Kaffir Lime is weak or absent. That usually means no controlled trial has tested it, not that a trial found it ineffective — the two are different, and we grade only what has been published.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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