What is Zhi Gan Cao Tang?

Zhi Gan Cao Tang is a Chinese herbal formula. The name means Honey-Fried Licorice Decoction. It is also known as Restore the Pulse Decoction.

It is sold as one product, but it holds many herbs. The lead herb is honey-fried licorice root. In Chinese medicine it is given for a weak, skipping or racing pulse, a pounding heart, tiredness and dry mouth.

Here is the short verdict. It is a well-known staple of Chinese medicine, but good human trial evidence is thin. Long use in a tradition is not proof that a remedy works, and that gap applies to every use listed on this page.

How does Zhi Gan Cao Tang work?

No one has shown how this formula works in the body. The ideas below come from tradition and from lab work, not from proof in people.

In Chinese medicine, the formula is said to feed the blood and the body's fluids and to steady the heart beat. That is a traditional way of speaking. It is not a test result.

The one effect that is well proven belongs to licorice, and it is a risk rather than a help. Licorice holds a sweet compound called glycyrrhizin. In large or long doses it makes the body hold on to salt and water, raises blood pressure and drives potassium down.

Low potassium can itself upset the heart beat. So the same herb that the formula is named after can cause the very problem the formula is used for.

What forms does Zhi Gan Cao Tang come in?

You may find it in these forms:

Raw dried herbs, sold as a pack to boil at home into a decoction (a strong tea made by boiling).

Granules or powder that you stir into hot water.

Pills, tablets or capsules made from a dried extract.

Ready-made liquid extracts.

Strength varies widely between makers, so the dose on one box does not match another.

Where it comes from:

The formula comes from the Shang Han Lun, a Chinese medical text. Zhang Zhongjing wrote it around 200 CE.

It has been in steady use in China, Japan and Korea ever since. In Japan it is known as a Kampo formula. Its long record sits in one tradition, Chinese medicine, rather than across many.

What does Zhi Gan Cao Tang help with?

• Palpitations (a pounding, fluttering or skipping heartbeat): This is the classic reason the formula is given in Chinese medicine, and it has been used this way for about 1,800 years. Human trial support is weak. Palpitations can come from a heart problem, a thyroid problem or low potassium, so get checked before you treat yourself.
• Irregular heartbeat (arrhythmia), as a traditional support only: Chinese hospitals have used this formula alongside heart medicines for slow or irregular beats. The published trials are small and poorly designed, so they cannot show whether it helps. Never use it in place of heart treatment, and never stop a prescribed heart drug to try it.
• Tiredness and weakness after a long illness: Tradition treats this formula as a builder for people who feel drained, thin and dry after fever or blood loss. There is no trial evidence that it restores energy. Ongoing tiredness needs a medical check, as it can signal anaemia (low iron or low red blood cells) or thyroid trouble.
• Shortness of breath on effort: Traditional texts pair breathlessness with a weak pulse and treat both together. No human trial supports this use. New or worsening breathlessness is a warning sign and needs a doctor, not a herb.
• Dry mouth and a dry throat: Several herbs in the formula are used in tradition to moisten the body. Evidence here is traditional only. Constant dry mouth can come from medicines or from diabetes, so it is worth asking a doctor about.
• Constipation with dryness: Hemp seed and rehmannia in the formula have a mild moistening and laxative role in tradition. This is a side benefit, not a main use, and it has not been tested in trials.
• Poor sleep that comes with a racing heart: Chinese medicine links restless sleep with an unsettled heart and uses this formula for that picture. There are no sleep trials to point to. Simple sleep habits and a check for anxiety or thyroid problems come first.

Which foods are rich in Zhi Gan Cao Tang?

1. Black licorice sweets: they carry the same glycyrrhizin as the herb and add to your total dose
2. Licorice root tea: another source of the same compound
3. Some herbal throat lozenges and 'liquorice' flavoured drinks: check the label for real licorice root, not just anise flavour

Practical Tips:

Salty food makes the fluid build-up worse, so go easy on salt while you take this formula.

What are the side effects of Zhi Gan Cao Tang?

• Swollen ankles, feet or face from held fluid
• Fast weight gain over days, which is fluid and not fat
• Raised blood pressure
• Low potassium (hypokalaemia), which can cause muscle weakness, cramps and an odd heartbeat
• Headache
• Stomach upset, loose stools or nausea
• Feeling more thirsty or passing less urine
• Rash or itching, which can mean an allergy

Good to know:

Most side effects come from the licorice, and they are dose-related. The more you take and the longer you take it, the higher the risk.

Mild swelling and a rise in blood pressure are the common ones. Serious cases of low potassium with muscle weakness, heart-rhythm changes or even paralysis have been reported with high-dose or long-term licorice.

These effects usually settle within weeks of stopping, but a severe drop in potassium is a medical emergency.

How much Zhi Gan Cao Tang should you take?

• Recommended daily: There is no safe dose set for taking this on your own. Because of the licorice, the amount and the length of use both matter, so a trained practitioner should set them. As a guide only, a traditional daily decoction uses roughly 9 to 12 grams of honey-fried licorice with the other herbs, boiled and split into two or three drinks in a day. Concentrated granules are usually taken at about 4 to 9 grams a day, split into two or three doses. Follow the maker's label, since strengths differ. Health bodies advise keeping glycyrrhizin from licorice under about 100 mg a day for most adults. Many people react at lower amounts. If you already eat black licorice sweets or drink licorice tea, count those in.
• Best time of day: Usually split across the day, such as morning and evening. Some people take a dose in the late afternoon if palpitations are worse in the evening.
• With or without food: Take it warm, between meals, or with a little food if it upsets your stomach.
• Time to effect: Tradition expects some change in a few days to two weeks. There is no trial data on how fast it works, or whether it works at all. Side effects from licorice can start within one to two weeks.
• How long to take it: Keep it short. Most practitioners use it for two to four weeks, then look again. Do not take it for more than about four to six weeks without a doctor checking your blood pressure and your potassium level with a blood test. Stop and reassess sooner if your ankles swell, you gain weight fast, or your blood pressure climbs.