What is Tan Xiang?

Tan Xiang is the sweet-smelling heartwood of the sandalwood tree (Santalum album). It is also known simply as Sandalwood. Chinese medicine uses it to ease chest and upper-belly pain that feels cold, tight or blocked.

In a Chinese formula it is usually a small, scented helper herb. It is rarely the main ingredient.

In TCM terms it is said to "move qi", warm the middle and stop pain. In plain words, herbalists reach for it when someone has a cold, gnawing ache below the breastbone. They also use it for belching, or for nausea that eases with warmth.

Here is the honest verdict on the evidence. Sandalwood has a long, well-recorded place in several old traditions. But good human trials of Tan Xiang as a medicine are more or less absent.

A long history of use tells you that people valued it. It does not tell you that the herb works. We say this once here, rather than in every section below.

How does Tan Xiang work?

No one has shown clearly how Tan Xiang works in the body. Its mechanism (the way it acts) is proposed, not proven.

The wood is rich in scented oils. Lab work suggests these oils can relax smooth muscle, the muscle in the gut wall. In cell and animal tests they also calm inflammation (swelling and heat).

A decoction (a simmered water tea) holds only small amounts of these oils. Whether that does anything inside a person has not been tested properly.

A second idea is simply smell. Many people find the scent of sandalwood calming. Part of any effect may come from scent and ritual, not from a drug-like action.

That is not a criticism of the herb. It is what the current evidence supports.

In TCM language, Tan Xiang is warm and acrid (sharp and pungent). It enters the Spleen, Stomach and Lung channels. It is used to unblock stuck qi in the chest and stomach.

That is a traditional way to describe what it does. It is not an account of how the body works.

What forms does Tan Xiang come in?

Tan Xiang is sold in several forms, and they are not the same thing.

Dried heartwood chips or shavings are the classic medicine form. They go into a decoction (a simmered water tea). The oils boil off easily, so the chips are added near the end, in the last five minutes.

Fine powder goes into pills, powders and some ready-made formulas. Granule extracts made for dispensaries are common in clinics today.

Sandalwood essential oil is a separate product. It is for scent and skin use only. It is not the same as the herb, and you should never treat it as a dose you swallow.

Incense sticks and cones are used for scent and ritual. They carry no medicinal dose at all.

Where it comes from:

Sandalwood has been prized for more than two thousand years across Asia. People used it for incense, carving, ritual and medicine.

Tan Xiang shows up in Chinese herb books from the Tang and Song periods onward. It sits in formulas for cold, painful chest and stomach trouble.

In Ayurveda the same wood is called chandana, a classic cooling remedy. It also turns up in Unani and Arabic medical writing.

More than one old tradition names it as a medicine, so its traditional standing is high.

Wild Santalum album is now heavily over-harvested. India protects it by law. That is why supply is tight and prices are high.

What does Tan Xiang help with?

• Cold, cramping pain in the upper belly: This is the classical use and the one most TCM practitioners would recognise. Tan Xiang is combined with herbs such as Sha Ren or Dan Shen for a dull, gnawing ache below the breastbone that eases with warmth and a hot drink. No published human trial has tested the herb for this on its own.
• Tight or heavy feeling in the chest: Traditional formulas use Tan Xiang for chest tightness described as stuck or blocked. This overlaps dangerously with angina (chest pain from a narrowed heart artery) and heart attack, so chest pain needs a doctor first, not a herb. There is no trial evidence that it helps heart-related chest pain.
• Belching, hiccups and nausea: Aromatic qi-moving herbs are a standard TCM answer to burping, hiccups and queasiness when the stomach feels cold. Support here is traditional and clinical experience only. Laboratory work on smooth-muscle relaxation is suggestive but does not prove a benefit in people.
• Restlessness and tension: Sandalwood scent is widely used in aromatherapy and meditation and many people find it settling. Studies in this area are small, short and hard to blind, since you cannot hide a strong smell from a participant. Treat any calming effect as pleasant rather than proven treatment.

What are the side effects of Tan Xiang?

• Nausea or upset stomach, above all on an empty stomach
• Dry mouth, or a strong taste that lingers
• Skin rash or itching where diluted oil is put on the skin (contact dermatitis, a rash from contact)
• Headache or queasiness from strong scent in a closed room
• Blood in the urine, or pain when you pass urine, after swallowing the essential oil (rare, and a reason to stop at once)

Good to know:

Tan Xiang is usually well tolerated as a small part of a herbal decoction (a simmered water tea). Reported problems are mild and not common.

The real risk sits with the strong essential oil. Swallowed sandalwood oil has been linked to irritation of the kidneys and urinary tract. Skin reactions to sandalwood oil and scented products are well recorded.

Treat the wood and the oil as two different things. They carry two different levels of risk.

How much Tan Xiang should you take?

• Recommended daily: There is no dose proven in trials. The figures below are traditional practice, not tested amounts. In a decoction, Chinese texts commonly use 2 to 5 grams of the wood per day, added in the final few minutes of simmering so the aroma is not boiled away. As a powder inside pills or capsules, 1 to 3 grams a day is typical. Essential oil is for smell and skin only. A few drops in a diffuser, or oil diluted to about 1 percent in a carrier oil for skin, is the usual approach. Do not swallow it.
• Best time of day: Usually split into two doses, morning and evening. For stomach discomfort, many practitioners give it about half an hour before meals.
• With or without food: Take it shortly before food, or with a little food if it feels harsh on an empty stomach.
• Time to effect: If it helps at all, people usually notice a settling of belly discomfort within a few days. Scent effects are immediate but brief.
• How long to take it: Short courses are the norm. Two to four weeks is a reasonable trial, then stop and reassess. If your symptoms have not clearly improved in that time, the herb is not the answer and something is being missed. Ongoing stomach or chest pain needs a diagnosis, not a longer herb course.