From the practitioner letters
Two herbs, six hundred years, and the pattern that keeps coming back when a patient runs herself down.
Will Sheppy, L.Ac. · Guest contributor · September 2026
Most of the recurrent-UTI patients I see have already done the antibiotic rounds. Two, three, sometimes five courses in a year. Each one works. Each one is followed, six or ten weeks later, by the same low burn and the same urgency, usually at the end of a week where they slept badly and ate badly and pushed through something they should not have pushed through.
Dr. Xuelan Qiu — Dr. Lan — is the herbal pharmacist behind the Botanical Biohacking formulas on the Chorus shelf and in my clinic, and she writes to practitioners most weeks. Her September letter took that exact picture and named the thing the antibiotic does not touch. I want to walk through what she wrote, because the distinction she draws is one I use in the treatment room constantly and rarely see written down this cleanly.
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The short version
Er Miao San is a two-herb formula — Huang Bai and Cang Zhu — written down by Zhu Danxi in the fourteenth century for what classical medicine calls damp-heat pouring downward. It is the formula behind Aquada. Traditionally it is used to support the body in patterns of lower-body heat and heaviness that recur under fatigue and stress. It is not an antibiotic and it is not a treatment for infection. In my own practice it runs alongside antibiotics in an acute episode, and on its own only as maintenance between them — an active or worsening urinary infection needs a culture and a clinician.
What Dr. Lan described
Dr. Xuelan Qiu — “Dr. Lan” — Botanical Biohacking
Her case is a licensed acupuncturist — someone who knows the territory from both sides. She feels a UTI starting. Not her first; she knows her own trigger, which is being exhausted, stressed and immune-low all at once. She happens to have a single sample vial from a seminar in her bag, and takes a capful in the car.
What she reports next is the part worth sitting with, because it is a description of sensation, not of outcome:
“By a quarter of the drive home, a cooling sensation begins traveling from below her stomach down into the bladder. The burning quiets in ten to fifteen minutes.”
— Dr. Lan, Botanical Biohacking practitioner letter, September 2026
Over the following hours she describes that coolness continuing — down the legs into the feet, up the arms, along the back. She stops the bottle short. No further symptoms that episode.
I want to be careful about what that is and is not. It is one practitioner's account of her own body, told to another practitioner. It is not a trial, it is not a controlled observation, and it is not evidence that a herbal formula clears a bacterial infection. What it is — and why I think Dr. Lan included it — is an unusually precise description of what damp-heat feels like when it starts to move. That is a clinical teaching object, and those are rarer than studies.
The pattern behind it
The classical name is 下焦湿热 — damp-heat in the lower jiao. Two pathogenic qualities, fused, sitting low in the body. Dr. Lan's division of labour between them is the most useful sentence in the letter:
“Heat gives the burning. Damp gives the recurrence — the pattern the body cannot fully clear on its own.”
— Dr. Lan, September 2026
That is the whole argument in two sentences. Antibiotics are very good at heat. They are indifferent to damp. If the damp is what makes the pattern sticky — what makes it return the next time the patient is run down — then clearing the heat alone and declaring victory is exactly how you end up with a patient on her fifth course in a year.
Signs that point downward and damp
- Thirstless dryness. Dry or sticky mouth, no real desire to drink.
- Urination. Scanty, hot, urgent, or painful out of proportion to findings.
- Heaviness below. Leg weakness, heavy thighs, red or swollen knees and ankles.
- Skin and discharge. Thick yellow discharge, pimples on the inner thighs, toenail fungus, dry scaling on the shins.
- Tongue and pulse. Thick coat, heaviest at the rear; soggy or slippery-rapid pulse.
- The trigger. It returns with fatigue, stress, alcohol, fried food, dairy, and humid weather — not at random.
Where this stops being a herbal conversation
Dr. Lan's own framing is that care continues alongside — not instead of. Refer out, and get a culture, when there is:
- Fever, rigors, or flank pain. Suspect upper tract. This is urgent.
- Visible blood in the urine, or symptoms escalating rather than settling.
- Pregnancy, or a patient who is immunocompromised, diabetic, or catheterised.
- Symptoms past about forty-eight hours without clear improvement.
- Male patients, in whom urinary infection is treated as complicated by default.
The formula — Er Miao San
“Er Miao San. The Two Marvel Powder. Two herbs — Huang Bai to clear heat from the lower jiao, Cang Zhu to dry the damp that heat has fused with.”
— Dr. Lan, Botanical Biohacking practitioner letter, September 2026
- Huang Bai (Phellodendron bark) — bitter and cold, with a downward-and-inward direction. It is the heat-clearing half, and its affinity is specifically for the lower burner rather than heat in general. Chorus's material comes from thirty-year-old trees in Dujiangyan.
- Cang Zhu (grey Atractylodes rhizome) — acrid, aromatic, drying. It is the damp half, and the reason the formula is not simply a cold, heat-clearing prescription that would eventually injure the middle. Wild-crafted on the Inner Mongolian steppe.
Zhu Danxi set it down in the fourteenth century and it has been in continuous use since. Two herbs is not a small formula because somebody ran out of ideas; it is small because the pattern it addresses has exactly two moving parts. The pairing has the property that good small formulas have — each herb covers the other's flank. Huang Bai alone is cold enough to be a problem over time. Cang Zhu alone is warm and drying enough to aggravate the heat. Together, neither happens.
On the Chorus shelf this is Aquada, made as herbal pills rather than a decoction — which, practically, is why patients actually take it at the moment they need it rather than three days later.
What I see in clinic
The patients I reach for this with most often are older, and the mechanical problem comes first: they have trouble emptying the bladder completely, and they get frequent UTIs because of it. What they are carrying between episodes is not acute inflammation. It is low-grade chronic inflammation from low-grade infection — the kind that will not go away, or will not fully clear with antibiotics.
That shapes how I use it, and it is where I want to put a harder line than the letter does. I use Aquada in combination with antibiotics, not instead of them. For an acute infection you definitely want the antibiotic. Aquada is what I add so the antibiotic is effective and the infection clears completely, rather than half-clearing and settling back into that low-grade state.
The second use is preventative, and it is the one that matches Dr. Lan's trigger list most closely: people who get UTIs frequently after sex, or when they are stressed. And for chronic bladder inflammation I am using it to help regulate the microbiome in the bladder — as maintenance, not as something aimed at an episode.
Two pairings from the letter are worth naming here because one of them is not on the Chorus shelf. Dr. Lan pairs Aquada with Microgard for the gut ground underneath the pattern — Chorus does not carry Microgard, and I have written about what it is on the clinic blog. The second is the Tibetan foot soak as a nightly external draw, which I have also written up separately; the logic is the same one that makes the soak useful for heavy summer legs — you are pulling downward and outward rather than pushing.
What the research adds — and what it doesn't
I am going to be blunt here, because this is a practitioner audience and the alternative is worse.
There is no indexed human trial of Er Miao San for urinary tract infection, cystitis, or any urinary condition. None. Dr. Lan's letter cites no study, and when I went looking I did not find one either. If you have been told otherwise, the citation is probably for a different formula or a different indication.
What does exist is small and pointed in a different direction. According to PubMed, Er Miao San appears in exactly two substantive pharmacology papers, both on rheumatoid arthritis and both in animals or cell culture. A 2023 study in Phytomedicine found the formula reduced paw swelling, arthritis index and pro-angiogenic signalling in adjuvant-arthritis rats, apparently via the Wnt/β-catenin pathway.1 A 2025 Fitoterapia paper reported that the formula and two of its constituents — phellodendrine from Huang Bai, atractylenolide-I from Cang Zhu — suppressed neutrophil extracellular trap formation in collagen-induced arthritis mice.2
Rats and mice, joints not bladders. You cannot carry that across to a patient with recurrent cystitis, and I would not try.
But there is one thing in those papers worth having. Both research groups, independently and in peer-reviewed journals, open by describing Er Miao San as the representative prescription for damp-heat pouring downward. That is not a marketing phrase and it is not Dr. Lan's phrase — it is how pharmacology researchers define the formula's indication before they run the experiment. The classical category has survived contact with the laboratory intact. That is a modest claim, but it is a real one, and it is more than most formulas can say.
The wider berberine literature — Huang Bai is berberine-rich — is large and includes work on bacterial adhesion and quorum sensing. It is also almost entirely preclinical where urinary pathogens are concerned, and berberine as an isolated compound is not the same intervention as a two-herb formula. I would not build a clinical argument on it.
How Dr. Lan recommends using it
“Aquada at twenty to twenty-five pills, two to three times daily, starting at the first prodromal symptom and continued through the episode.”
— Dr. Lan, Botanical Biohacking practitioner letter, September 2026
For patients whose baseline is chronically damp-heat, she suggests a lower maintenance dose — ten to twenty pills, two to three times daily — across the humid months, with the aim of reducing how often the pattern returns. One vial runs ten to twenty-five days depending on dose. She also asks for restraint from the classical aggravators: alcohol, deep-fried food, and dairy in excess.
The cautions that belong with a bitter-cold and drying pair: it is not a formula for a patient who is cold, loose in the stool, and depleted, and it is not built for long open-ended use. Cang Zhu is drying and Huang Bai is cold; in a yin-deficient or already-dry patient, both are working against you. As always, dosing and duration belong with the practitioner who can see the tongue.
On the Chorus shelf
Aquada
Er Miao San as herbal pills — Huang Bai from thirty-year-old trees, wild-crafted Cang Zhu.
Shop Aquada →Related formulas
If the damp-heat picture sits higher and drier — heavy head, foggy mornings, neck tension — Warm Hearth is the phlegm-damp formula rather than the lower-jiao one. If the patient is waterlogged and too depleted to tonify, Sol is the gentler starting point. The Tibetan foot soak is Dr. Lan's external pairing for this pattern.
References
- Chen S, Wang J, Wang J, et al. Wnt/β-catenin signaling pathway promotes abnormal activation of fibroblast-like synoviocytes and angiogenesis in rheumatoid arthritis and the intervention of Er Miao San. Phytomedicine. 2023;120:155064. doi:10.1016/j.phymed.2023.155064 (animal and cell study)
- Tang R, Qin ZF, Yin JH, et al. Er Miao San and its main components phellodendrine and atractylenolide-I exert anti-rheumatoid arthritis effects by inhibiting PAD4 and thereby reducing the formation of NETs. Fitoterapia. 2025;185:106771. doi:10.1016/j.fitote.2025.106771 (animal and cell study)
Both records were retrieved from PubMed and checked for retraction notices; neither is retracted. No human trial of Er Miao San for urinary conditions was found.
Further reading from Valley Health Clinic: Microgard by Botanical Biohacking · Tibetan Herbal Foot Soak: For Heavy, Swollen Summer Feet · Sol Tea: For the Foggy, Heavy Head That Feels Waterlogged
Common questions
What is Er Miao San used for?
Traditionally it is used for what Chinese medicine calls damp-heat pouring downward — a lower-body picture of heat with heaviness that includes urinary discomfort, hot swollen knees and ankles, heavy legs, discharge, and a thick greasy tongue coat toward the back. It is a pattern-based formula, not a condition-based one.
Is Er Miao San the same as Er Miao Wan?
Same formula, different preparation. San means powder and wan means pill; the herb pair is identical. Aquada is made as pills.
Can it replace antibiotics for a UTI?
No, and nothing in Dr. Lan's letter suggests it should. An established urinary infection is a bacterial problem that needs a culture and a clinician, and fever, flank pain, blood in the urine, or symptoms that escalate are reasons to be seen the same day. My own use is the opposite of replacement: in an acute episode I run Aquada with the antibiotic, so the course clears the infection completely instead of half-clearing it. On its own, it is for the quiet stretch in between — the terrain the infection keeps returning to.
Who should avoid it?
Huang Bai is cold and Cang Zhu is drying, so the pairing is a poor fit for someone who runs cold, has loose stools, or is markedly yin-deficient and dry. It is not intended for open-ended long-term use. Pregnancy, and any prescription medication, is a conversation with your own practitioner first.
Why does the pattern keep coming back?
In Dr. Lan's framing, because the damp half of it never left. Heat produces the acute burning and responds to treatment readily; damp is the slow, sticky quality that makes the same picture reassemble the next time the patient is tired, stressed, or eating badly