Sheng Ma Ge Gen Tang
Quick Facts
- What it is: A classical Chinese four-herb formula, counted as a single drug (TCM formula) and also known as Cimicifuga and Kudzu Decoction, used at the start of a feverish illness with a rash.
- Main uses: Early-stage measles rash in children (traditional use), First 48 hours of a cold or flu with fever and chills, Rashes slow to come out during a fever
- Best for: Very short courses at the onset of a feverish illness, under guidance
- Active ingredients: Puerarin and daidzein (from kudzu root), Triterpene glycosides and cinnamic acid derivatives (from cimicifuga root), Paeoniflorin (from red peony root), Glycyrrhizin (from licorice root)
- Forms: Concentrated granules or powder, Raw dried herbs for decoction (a strong herbal tea), Pills (teapills), Bottled liquid extract
- Time to effect: Traditionally within one to two days, if at all; no trial data.
- Side effects: Usually mild stomach upset; the licorice can raise blood pressure and lower potassium.
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What is Sheng Ma Ge Gen Tang?
Sheng Ma Ge Gen Tang is a classical Chinese herbal formula, also known as Cimicifuga and Kudzu Decoction. It is counted as a single drug (TCM formula): four herbs are always taken together as one preparation.
Those four herbs are sheng ma (cimicifuga root), ge gen (kudzu root), chi shao (red peony root) and gan cao (licorice root). It was written down for the first day or two of a feverish illness with a rash, above all measles in children whose rash was slow to come out.
Modern practitioners still use it only at the very start of such an illness, for a few days at a time. The evidence verdict is blunt: it has a long record in Chinese medicine and almost no modern human trial evidence. Long traditional use tells you that people have relied on it; it is not proof that it works.
How does Sheng Ma Ge Gen Tang work?
Nobody has shown in people how this formula works, so what follows is theory and laboratory work, not proof.
In traditional language it is said to "release the exterior" and "vent the rash" — to push a surface illness and its rash outward so the fever breaks and the spots come up cleanly.
Lab and animal studies on the separate herbs give clues only. Kudzu root and cimicifuga contain plant compounds that lower fever and calm inflammation (swelling and irritation) in animals. Licorice has mild anti-inflammatory effects in the same kind of testing.
None of this has been tested in humans as the finished four-herb decoction, so treat the mechanism as an idea rather than a finding.
What forms does Sheng Ma Ge Gen Tang come in?
Most people meet it as a ready-made granule or powder that you stir into hot water.
Raw dried herbs are also dispensed by practitioners to be simmered at home into a decoction (a strong herbal tea). This is the classical method and the dose is set by the practitioner.
Pills (teapills) and bottled liquid extracts are sold too, often under the pinyin name or as "Sheng Ma Ge Gen Wan".
Check that the label lists all four herbs with amounts. Western products labelled "black cohosh" are a different plant (Actaea racemosa) and are not sheng ma.
Where it comes from:
The formula is recorded in a Song dynasty Chinese text on children's illnesses, written around the 12th century.
For centuries it was the standard choice when a child's measles rash was slow to appear and the fever would not break.
It also passed into Japanese Kampo medicine, where it is known as shoma-kakkon-to. It is taught in standard TCM formula courses today.
If this is an emergency
Some reactions to Sheng Ma Ge Gen Tang need urgent care. Call your local emergency number or go to an emergency department straight away — do not wait to see whether it passes.
Who should avoid Sheng Ma Ge Gen Tang?
- Never use this formula in place of measles vaccination, or in place of urgent medical care for a child with a high fever and a rash.
- Do not use if you are pregnant or trying to become pregnant.
- Do not use if you are breastfeeding.
- Do not use if you have high blood pressure (hypertension).
- Do not use if you have low potassium (hypokalaemia) or take a water tablet (diuretic) that lowers potassium.
- Do not use if you have heart failure, an irregular heartbeat (arrhythmia), or take digoxin.
- Do not use if you have kidney disease or liver disease.
- Do not use if you take corticosteroids such as prednisolone (steroid medicines used for inflammation).
- Do not use if you have a hormone-sensitive cancer such as breast or womb cancer, or take tamoxifen, unless your cancer doctor agrees.
- Do not use if you take warfarin or another blood thinner, unless your doctor has checked it.
- Do not give it to a child unless a qualified practitioner and your doctor have both agreed.
- Do not use if you are allergic to licorice, kudzu, cimicifuga or peony.
- Do not keep taking it for longer than about a week unless a practitioner is monitoring you.
When should you see a doctor?
Get emergency help if a fever with a rash comes with a stiff neck, a severe headache, confusion, sleepiness that is hard to rouse, trouble breathing, or a rash that does not fade when you press a glass against it. These can be signs of a serious infection.
Call your doctor if the fever lasts more than two days, if a child is not drinking or passing urine, or if the rash is spreading fast or blistering.
Stop the formula and speak to a doctor if you notice puffy ankles or face, muscle weakness or cramps, a pounding or irregular heartbeat, or a jump in your blood pressure. These point to the licorice in it affecting your potassium.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
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