Siler.
A Chinese root, fang feng, used for everyday immune resilience and seasonal comfort. It is almost always taken inside a three-herb mixture rather than alone.
- Category
- Herb
What Siler is, and what it does.
- Does it work
- Suits people using traditional Chinese formulas rather than single herbs. If you want an ingredient studied on its own, most of the research here covers the blend.
- How much to take
- No daily amount is on record for the root by itself. Start with what your formula states, since traditional practice dosed the three-herb mixture rather than this root alone.
- Time to feel it
- Nobody has measured a timeline for the root alone. Traditional courses run for weeks, often across a whole season.
- The first dose
- Day one is typically uneventful. Decoctions taste bitter and warming, and that flavour is the main thing anyone notices on the first day.
- With regular use
- Weeks of daily use is the traditional pattern, taken through colder months for everyday defence support. Long-term data on the root alone is scarce.
- How well tolerated
- Well tolerated at food-herb amounts. It is an Apiaceae root, so check with your clinician if you react to celery or carrot family plants, or if you are pregnant.
- How it feels
- Warming and bitter going down. Beyond taste, most people report no distinct sensation, which is usual for a herb taken as a course.
- The overlooked benefit
- The compounds that reach your blood are not the ones in the root. Gut bacteria strip the sugar off the chromones first, so your microbiome shapes what you absorb.
The proof, claim by claim.
These words describe the research, not the molecule's worth. Research strength is how much work stands behind one claim, and it is never a product score.
- Immune resilience as part of a traditional three-herb formulaNarrative review
- Seasonal respiratory comfortNarrative review
- A healthy inflammatory responseAnimal study
- Bacterial hydrolysis of chromone glucosides before absorptionIn vitro study
Why these belong in the same formula. Each row says what the basis is, from settled biochemistry through to a trial that measured the pair.
Siler is one of the three herbs in Yupingfeng San, alongside astragalus and atractylodes, and it is not normally used alone in that context. The pairing is a formula convention with a long documented history rather than a tested two-ingredient combination. Modern work on the formula measures the three together, so effects attributed to it cannot be assigned to siler on its own.
The chromone constituents of siler circulate largely as glucosides, and bacterial glycosidases cleave them to the free aglycones. Deliberate fermentation of the formula with Bacillus coagulans shifted both its microbial and its metabolite profile, which shows the constituent pattern is microbially modifiable. What that shift means for a person taking it has not been established.
Licorice appears as a harmonising and taste-modifying herb across a large fraction of classical formulas, siler-containing ones among them. The role is formulation convention rather than a specific interaction with siler chemistry. Worth noting that licorice carries its own potassium and blood pressure considerations at sustained intake.
Fresh ginger is routinely added to decoctions containing siler in traditional practice. The basis is preparation custom, documented in formula texts. Read it as convention rather than as measured combination pharmacology.
Siler chromones are heavily conjugated after absorption, and piperine slows the conjugation and efflux steps that clear several plant compound classes. The direction is predictable from piperine's known behaviour. No study has measured it on cimifugin or its glucoside specifically, so this stays mechanistic.
Nothing specific on file for Siler. Match the label to the daily amount above, and tell your doctor what you take.
Not medical advice. Show the label to your pharmacist.What Siler actually does.
Siler root is defined by two particular chromone glycoside compounds, which are the ones official pharmacopoeia standards use to test and verify it.
Gut bacteria break down those chromone compounds into different forms before they're absorbed, so what ends up circulating in the body isn't the same as what's in the raw root.
The root also contains coumarins and polyacetylene compounds typical of its plant family, but these are a separate group of compounds that standard chromone testing doesn't capture.
The chromone compounds are concentrated in the root and drop once the plant flowers, which is why official standards call for root harvested before flowering.
Where Siler comes from.
A dried root from northern China, known as fang feng. It is nearly always used as part of a three-herb mixture rather than on its own, so most of what has been studied is the mixture, not this root by itself.
Made from a plant. What ends up in the capsule tracks the harvest, so batch testing and a stated marker matter more here than with a made molecule.
Root of an Apiaceae perennial cultivated and wild-collected in northern China, Mongolia and eastern Siberia, harvested before the plant bolts.
Roots are washed, sliced and sun or oven dried. The fibrous root neck is trimmed.
The chromone glucosides are water-soluble, so plain hot water recovers the marker fraction efficiently.
HPLC against prim-O-glucosylcimifugin and 4'-O-beta-D-glucosyl-5-O-methylvisamminol, the pair specified in the Chinese Pharmacopoeia monograph.
Supplied as sliced root for decoction, as a formula granule, or as a dried standardised extract.
The forms it comes in.
The essence, in one line each.
- Fermenting the siler-containing formula Yupingfeng San with Bacillus coagulans shifted both its microbial community and its measured metabolite profile.In vitro study. Kang Y et al., 2025 (PeerJ). PMID 40212372 ↗
These are the studies our verdict leans on, chosen from the 1 we read for Siler. The full linked list is below.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This information is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before starting any supplement regimen.