What is Quillay?

Quillay is the inner bark of a Chilean evergreen tree, Quillaja saponaria, also called soap bark. The bark is full of saponins, natural soap-like compounds that foam when you shake them in water. People in Chile have long used it as a body and hair wash, and as a folk cough remedy.

Most quillay harvested today does not go into herbal medicine at all. Its extract is a legal foaming agent in soft drinks and cocktail mixers, and a purified part of it, called QS-21, is an ingredient in some licensed vaccines.

Evidence verdict: quillay has a long, well-documented history of use in Chile, but almost no human trial evidence supports the ways it is sold as a herbal remedy. Traditional use means a plant has been valued for generations. It does not prove the plant works, and it does not prove the plant is safe.

How does Quillay work?

The short answer is that nobody has shown, in people, how quillay works as a medicine.

Saponins act like a natural detergent. They break up oils and grease, which is why the bark foams and why it has been used to wash hair and skin. That part is simple chemistry, not a medical effect.

The old cough idea is that swallowing a bitter, slightly irritating saponin tea makes the stomach lining complain, and the body answers by producing thinner mucus in the airways. This is a theory borrowed from other saponin plants. It has not been tested properly in people taking quillay.

Saponins can also poke holes in cell membranes, the outer skin of a cell. In the lab this helps vaccine makers get an immune response going. It is also the reason large amounts taken by mouth can damage the gut lining and, if absorbed, red blood cells.

What forms does Quillay come in?

Quillay is sold mainly as dried inner bark, in strips or chips. It is simmered in water to make a foaming wash or a weak tea. You will also see liquid extracts, tinctures and dried powdered extracts.

Most quillay made today is not sold as a herbal medicine. It goes into shampoos, soaps, foaming drinks, film coatings and animal feed. The purified saponin QS-21 is made under pharmaceutical control for use in vaccines, and is never sold to the public.

Where it comes from:

Quillay belongs to the Mapuche people of central Chile, and the name comes from the Mapudungun word for washing. The bark was the everyday soap and hair wash long before European contact.

Use spread through Chile, Peru, Bolivia and into Latin American folk practice, where a bark decoction was also taken for stubborn chest coughs. Nineteenth-century traders shipped the bark to Europe as a soap substitute and a foaming agent.

What does Quillay help with?

• Chesty cough with thick mucus: This is the best-known internal use, and it rests on tradition alone. Chilean and wider Latin American folk practice used a weak bark decoction to loosen a tight chest. No controlled human trial has tested quillay for cough, so we cannot tell you whether it helps or how much is safe to drink.
• Dandruff and itchy scalp: Quillay foams and strips oil from hair, which is why it was the traditional shampoo. A cleaner scalp may feel less itchy. There is no trial showing it treats dandruff better than an ordinary shampoo, and the wash can sting if it gets in your eyes.
• Washing hair and skin: This is the use with the strongest footing, and it is practical rather than medical. The saponins genuinely lift grease, so the bark works as a mild soap. Nothing here is a treatment claim.
• Head lice: A bark rinse was used in folk practice to help comb out lice. We found no human study testing this. Proven lice treatments exist from a pharmacy, and you should use those first.
• Aching joints: Some Latin American folk practice used a warm bark wash on sore joints. The evidence for this is tradition only, with no laboratory or human work to support it. Do not use it in place of care for a joint that is swollen, hot or badly painful.

Which foods are rich in Quillay?

1. Soft drinks and root beer: quillaja extract is added as a legal foaming agent
2. Cocktail mixers and slush drinks: used to build and hold a foam head
3. Some frozen desserts and flavoured waters: small amounts as a foaming or emulsifying aid

Practical Tips:

These food amounts are tiny, tightly regulated and are not a way to take quillay as a remedy.

What are the side effects of Quillay?

• Burning or scratchy feeling in the throat
• Stomach pain, nausea and vomiting
• Diarrhoea
• Skin redness or itching from washes
• Stinging and redness if it gets in your eyes
• Sneezing, coughing and wheezing from breathing the bark dust
• Asthma-like breathing trouble in people who handle the dust often
• Liver damage after large or repeated amounts by mouth
• Damage to red blood cells (haemolysis, the breaking apart of red blood cells) if large amounts reach the bloodstream

Good to know:

Mild throat and stomach upset is the common problem, and it usually settles once you stop.

The serious effects are tied to dose. Small amounts in a drink or a hair wash are not the concern. Swallowing strong extracts, or a lot of bark tea, is what has been linked to liver injury and to red blood cells breaking apart.

Breathing the dust is a separate risk and mostly affects workers who process the bark. If you are crushing dry bark at home, do it outdoors and do not lean over it.

How much Quillay should you take?

• Recommended daily: There is no established safe dose of quillay by mouth. No health authority has set one, and no trial has tested one. Traditional practice used a weak decoction, roughly 1 to 2 grams of dried bark simmered in a cup of water, taken once or twice a day for a short spell. Treat that as history, not a recommendation. For external washing, the bark is simmered in water, cooled and strained, then used on hair or skin like a mild soap. Do not swallow the wash, and keep it out of your eyes. The tiny amounts of quillaja extract used as a foaming agent in soft drinks are regulated and are far below any amount used as a remedy.
• Best time of day: No time of day has been shown to matter. Traditional cough use was spread through the day; washes were used whenever you washed.
• With or without food: If taken by mouth at all, take it with or just after food. Saponins irritate an empty stomach and are more likely to cause nausea and stomach pain.
• Time to effect: As a wash, the foaming and cleaning effect is immediate. For any internal use, there is no reliable information on how quickly, or whether, anything happens.
• How long to take it: If you use it at all, keep it short. Traditional internal use was a few days for an active cough, not weeks. Stop after three days if nothing is improving, and see a doctor instead. Long or repeated internal use is not supported by any evidence and raises the risk of gut and liver harm.