Educational information, not medical advice — ask your doctor or midwife.
Sekko is a mineral used in Kampo, the traditional medicine of Japan. It is gypsum, the same soft white rock used to make plaster. Chemists call it hydrated calcium sulfate, a calcium salt that holds water inside it.
It is used as a single drug and in many Kampo formulas. The old texts give it for "heat" signs: a high fever with strong thirst, sweating, a red face, and a hot dry cough. It is meant to cool, not to feed or build up the body.
Sekko has a long, steady record in East Asian medicine. Human trials of Sekko on its own are essentially absent. Long use is not proof that something works, and that caution applies to everything on this page.
No one has shown how Sekko works in the body, and the honest answer is that we do not know.
Kampo doctors chose it for its "cold" nature. In that older way of thinking, it drains heat from the chest and stomach and eases thirst. This is a traditional idea, not a tested mechanism.
Gypsum barely dissolves in water. So a batch of tea made with it carries only a small amount of calcium. Lab and animal work has looked at fever and calcium handling, but this work does not tell you what happens in a sick person.
Sekko comes as a raw mineral, crushed into a coarse powder or small chunks.
Common forms you may meet: - Crushed raw gypsum, boiled in water as part of a Kampo decoction (a strong tea) - Calcined gypsum, roasted first, used mostly on the skin in some traditions - Granules or dried extract powders of whole Kampo formulas that contain Sekko - Capsules or tablets of those same formulas
In Japan, most people meet Sekko inside a named formula rather than alone. Byakkokaninjinto and Makyokansekito are two well-known examples.
Sekko appears in the oldest Chinese drug book, the Shennong Bencao Jing, written around two thousand years ago.
It then entered the Shanghan Lun, the classic text on fevers, as the main mineral in White Tiger Decoction. Japanese Kampo doctors took these formulas up and have used them for centuries.
It is still listed in the Japanese Pharmacopoeia today and is stocked by Kampo pharmacies.
Get medical help the same day if a fever stays above 39C for more than two days, or if you have trouble breathing, chest pain, a stiff neck, confusion, a rash that does not fade when pressed, or you cough up blood.
Stop taking it and call your doctor if you feel very thirsty, pass a lot of urine, vomit, feel muddled or feel very weak. These can be signs that blood calcium has risen too high.
Tell your doctor or pharmacist that you are taking a Kampo formula, especially if you take antibiotics, thyroid medicine, bone medicine or a heart drug.
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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