Educational information, not medical advice — ask your doctor or midwife.
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.
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.
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.
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.
See a doctor promptly if your skin or the whites of your eyes turn yellow, your urine goes dark, or you get pain under your right ribs. These can be signs of a liver problem.
Get urgent help if you have trouble breathing, swelling of the face, lips or tongue, or a spreading rash after taking it.
Also see a doctor if you bruise easily or bleed more than usual, if a cold comes with a fever above 39C or breathlessness, or if a new fluttering or pounding heartbeat starts. Chest pain, fainting or a heartbeat that will not settle needs emergency care, not a herb.
Tell your doctor and pharmacist that you are taking this, especially if you are on blood thinners or diabetes medicine.
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 Gui Zhi 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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