What is Sekko?

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.

How does Sekko work?

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.

What forms does Sekko come in?

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.

Where it comes from:

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.

What does Sekko help with?

• High fever with strong thirst: This is the classic reason Kampo uses Sekko. It is the core sign for White Tiger Decoction: high fever, a lot of sweat, big thirst, and a strong pulse. No trial has tested Sekko alone against a placebo for fever in people.
• Hot, dry cough and wheezing: Sekko is a main part of Makyokansekito, a formula given for a barking, hot cough with wheezing. Studies in China have looked at this whole formula for chest infections. They cannot tell you what Sekko itself contributed.
• Heavy sweating with a hot feeling: Tradition pairs sweating with fever and thirst as one picture, and treats it with Sekko. There is no human trial evidence for this use. See a doctor if you sweat heavily at night or lose weight without trying.
• Dry mouth and thirst: Byakkokaninjinto, a formula built on Sekko, is given in Japan for thirst and a dry mouth. Some Japanese reports describe its use in people with diabetes. This is not proof that Sekko lowers blood sugar, and it must never replace diabetes treatment.
• Mouth sores and sore, swollen gums: Old texts treat these as "stomach heat" rising to the mouth and use Sekko-based formulas. The evidence here is traditional only. Painful gums that do not settle need a dentist.
• Heat rash and itchy hot skin: Kampo adds Sekko to formulas for red, hot, itchy skin. Calcined gypsum has also been dusted on skin in folk use. Human trial evidence for either use is lacking.

Which foods are rich in Sekko?

1. Firm tofu: many makers use calcium sulfate as the setting agent
2. Some breads and baked goods: calcium sulfate is a legal food additive (E516)
3. Brewing water for beer: brewers add gypsum to harden the water
4. Some mineral waters: they pick up calcium sulfate from rock

Practical Tips:

Food-grade calcium sulfate in tofu or bread is a normal part of many diets and is not the same as taking a medicinal dose.

What are the side effects of Sekko?

• Upset stomach or nausea
• Loss of appetite
• Constipation
• Loose stools in some people
• Feeling cold or chilly
• Rarely, signs of too much calcium in the blood: strong thirst, passing a lot of urine, feeling weak, confusion

Good to know:

Most reported effects are mild and settle when you stop. They come mainly from the stomach.

The serious concern is calcium. Gypsum barely dissolves, so little calcium usually gets in. But in someone with kidney trouble, or someone already taking calcium or high-dose vitamin D, blood calcium can climb too high.

Stop and get medical advice if you feel very thirsty, pass a lot of urine, feel muddled, or feel unusually weak.

How much Sekko should you take?

• Recommended daily: There is no dose set by modern research. What follows is the traditional Kampo range, not a recommendation. Kampo texts use roughly 5 to 15 grams of crushed raw Sekko a day in a decoction. Some classical fever formulas go higher, up to about 30 grams, under close supervision. Sekko is normally boiled first, for 20 to 30 minutes, before the other herbs go in. Because it hardly dissolves, this long boil is part of the method. Get your dose from a trained Kampo or Chinese medicine practitioner rather than guessing.
• Best time of day: Kampo gives fever formulas in two or three doses spread through the day. For an acute fever, timing follows the illness rather than the clock. Do not take it at the same time as other medicines.
• With or without food: Kampo formulas are usually taken on an empty stomach, about 30 minutes before a meal or between meals. If it upsets your stomach, take it with a little food. Keep a gap of at least two hours from any other medicine you swallow.
• Time to effect: Tradition expects a fever formula to help within hours to a day or two. There are no trials to confirm this. If a fever is still high after two days, see a doctor.
• How long to take it: Sekko is a short-term drug in tradition, not a daily tonic. It is given while the fever and thirst last, often only a few days. If nothing has changed after two or three days, stop and get medical advice. Long daily use is not a traditional pattern and adds needless risk of too much calcium.