What is Gui Zhi?

Gui Zhi is the dried young twig of the cassia cinnamon tree (Cinnamomum cassia). It is a single drug (TCM herb), also known as Cinnamon twig, and it is one of the most-used warming herbs in Chinese medicine. Practitioners reach for it at the start of a common cold with chills, and for aching joints and cold hands and feet.

It is almost never taken on its own. It is the lead herb in classic formulas such as Gui Zhi Tang (Cinnamon Twig Decoction) and appears in hundreds of others, usually as a small part of a larger mix.

On the evidence: Gui Zhi has a very long and well-documented traditional record, but we could not find controlled human trials of the twig given by itself. Long traditional use tells you a herb has been valued; it does not tell you it works, and that distinction holds for everything on this page.

How does Gui Zhi work?

In Chinese medicine terms, Gui Zhi is described as warm and acrid. It is said to "release the exterior" (help you sweat out an early chill) and to "warm the channels" (ease cold, stiff, aching limbs).

In modern terms, the twig contains cinnamaldehyde and related aromatic oils. Laboratory and animal studies suggest these can widen small blood vessels, reduce some inflammation signals and act against some bacteria.

Those findings come from test tubes and animals, not from people taking Gui Zhi for a cold. Treat any mechanism story here as a plausible idea, not a proven explanation.

What forms does Gui Zhi come in?

Gui Zhi is sold and used in several forms:

Sliced or chopped dried twig, simmered into a decoction (a strong tea made by boiling). This is the traditional form and the most common one.

Granules or powdered extract, stirred into hot water.

Patent pills and capsules containing a whole formula, such as Gui Zhi Tang or Gui Zhi Fu Ling Wan.

Cinnamon essential oil is a different product. It is highly concentrated, is not Gui Zhi, and must never be swallowed.

Where it comes from:

Gui Zhi appears in the Shang Han Lun (Treatise on Cold Damage), compiled by Zhang Zhongjing around 200 CE. The very first formula in that text is Gui Zhi Tang, built around this twig.

It has stayed in continuous use in Chinese, Japanese Kampo and Korean medicine ever since, and is listed in the modern Chinese Pharmacopoeia. That gives it a strong standing inside one major tradition.

What does Gui Zhi help with?

• Early common cold with chills and mild sweating: This is the classic use, and it is traditional rather than proven. Gui Zhi Tang is given in the first day or two of a chill, when you feel cold, achy and are sweating a little. We found no controlled trial testing Gui Zhi alone for colds. Some trials of whole Kampo and Chinese formulas exist, but they cannot tell you what this one twig contributed.
• Aching, stiff joints that feel worse in cold weather: Traditional texts use Gui Zhi in formulas for limb pain that eases with warmth. It is usually combined with other herbs, never given alone. Human evidence for the twig itself is absent. Laboratory work on cinnamaldehyde shows some anti-inflammatory activity, which is a long way from pain relief in a person.
• Cold hands and feet: Gui Zhi is described as warming the outer body and the limbs, and it is a standard choice when someone chronically feels cold. This rests entirely on traditional practice. No trial has measured hand or foot temperature or circulation in people taking it.
• Period pain linked in Chinese medicine to cold: Gui Zhi appears in formulas such as Gui Zhi Fu Ling Wan, which is used for period pain and for fibroids (non-cancerous growths in the womb). Trials of that whole formula have been run, mostly in China, with mixed quality. Those results belong to the formula, not to Gui Zhi. Do not read them as evidence for the single herb.
• Mild palpitations within traditional formulas: Several classical formulas containing Gui Zhi were written for a fluttering or pounding heartbeat. This is a historical indication only. New or worsening palpitations need a medical assessment, not a herb. See a doctor first.

Which foods are rich in Gui Zhi?

1. Cassia cinnamon bark - the same tree as Gui Zhi, so kitchen cinnamon carries the same cinnamaldehyde and coumarin
2. Cinnamon tea and mulled drinks - a mild everyday source of the same compounds
3. Chinese five-spice powder - contains cassia cinnamon

Practical Tips:

Food amounts of cinnamon are far smaller than a medicinal decoction, but they count towards your total coumarin if you use cassia heavily every day.

What are the side effects of Gui Zhi?

• Heartburn or a burning feeling in the stomach
• Nausea
• Feeling hot, flushed or restless
• Excessive sweating
• Dry mouth and thirst
• Mouth or throat irritation from the strong taste
• Skin rash or itching in people allergic to cinnamon
• Rarely, liver irritation with high or long-term doses, because of the coumarin in cassia

Good to know:

At traditional doses and for short courses, most people tolerate Gui Zhi well, and the common complaints are mild stomach upset or feeling too warm.

The serious concern is liver irritation from coumarin, which is linked to heavy or prolonged use of cassia cinnamon rather than a few days of tea. Stop and get checked if your skin or the whites of your eyes turn yellow, your urine turns dark, or you get pain under your right ribs.

Allergic reactions to cinnamon are uncommon but real, and can include rash, swelling or wheezing.

How much Gui Zhi should you take?

• Recommended daily: There is no dose established by modern research. What follows is traditional practice, and it assumes a trained practitioner has chosen the herb for you. In a decoction, 3 to 9 grams of dried twig per day is the usual range in Chinese pharmacopoeia texts, simmered in water and split across two or three servings. Granules and patent pills vary a lot in strength. Follow the label on the product you actually bought, and do not stack two products containing the same herb.
• Best time of day: Traditionally taken warm, in two or three doses spread through the day. For a cold, the classic instruction is to take it warm and then rest under a blanket to encourage a light sweat.
• With or without food: Usually taken between meals, warm. If it upsets your stomach, take it with a little food instead.
• Time to effect: For an early chill, traditional texts expect a response within hours to a day. For aching joints or cold limbs, any change would be gradual over one to several weeks. None of these timings come from trial data.
• How long to take it: For a chill or early cold, traditional use is short: a few days at most, stopping once you feel better. For longer-running problems like joint ache, check in with the practitioner who prescribed it after two to four weeks. If nothing has changed by then, stop rather than continuing indefinitely. Avoid long unbroken months of use. The coumarin in cassia is a reason to keep courses short.