What is Xiao Feng San?

Xiao Feng San, literally "Eliminate Wind Powder", is a multi-herb formula recorded in 1617 in Chen Shigong's surgical and dermatological text Wai Ke Zheng Zong. In Chinese medicine, "wind" describes symptoms that move, come and go, and itch — which is why this formula was written for skin, not for colds. It combines dispersing herbs (schizonepeta, saposhnikovia, cicada moulting, burdock seed) with cooling herbs (gypsum, anemarrhena, rehmannia), a drying herb (atractylodes), a bitter anti-itch herb (Sophora flavescens), blood-nourishing angelica and sesame, a draining herb (mu tong), and licorice to bind the formula together.

In Japan the same prescription is dispensed as Shofusan, one of the standard Kampo granule products covered by national health insurance, most often for eczema and urticaria with strong itch and oozing.

The traditional picture it targets is specific: skin that is red and hot, that itches badly, that may weep or crust, and that gets worse with heat, sweating, alcohol or spicy food. It is not the formula traditionally chosen for dry, pale, cracked, cold-type skin — practitioners would pick a different prescription for that. That specificity matters, because most of the modest trial evidence has been collected in atopic dermatitis populations rather than in people matched to the traditional pattern.

How does Xiao Feng San work?

Honestly, the mechanism in humans is not established. Laboratory and animal work suggests the combined extract can dampen allergic and inflammatory signalling — reduced histamine-driven skin reactions, lower IgE and inflammatory cytokine levels in mouse dermatitis models, and antihistamine-like activity from cicada moulting and schizonepeta. Sophora flavescens alkaloids (matrine, oxymatrine) have anti-itch and anti-inflammatory activity in cell and animal studies, and gypsum plus anemarrhena are traditionally the "cooling" core. None of this has been confirmed as the operating mechanism in treated patients, and a 13-herb decoction is difficult to reduce to a single pathway.

What forms does Xiao Feng San come in?

Granulated extract is the standard modern form in both Japan and Taiwan — Kampo Shofusan granules are typically dispensed at 7.5 g of extract granules per day split into two or three doses. Raw-herb decoctions are still used where a practitioner wants to adjust proportions, add herbs for a particular presentation, or remove one (licorice is commonly reduced in people with blood pressure concerns). Pills and capsules exist but are usually lower in dose per unit and slower-acting. Quality varies significantly between manufacturers; Japanese and Taiwanese GMP products carry the most consistent labelling of what is actually in the box.

Where it comes from:

The formula appears in Wai Ke Zheng Zong (1617), a Ming dynasty text devoted to external medicine — sores, ulcers and skin disease. It was written for "wind-damp-heat" rashes: itchy eruptions with oozing fluid and redness. It entered Japanese Kampo practice and was standardised in the 20th century as Shofusan, a listed prescription product. In modern Chinese and Taiwanese hospital dermatology departments it remains one of the most frequently prescribed herbal formulas for eczema and urticaria, often modified rather than used exactly as written. Its four-century record is real; it is a record of clinical use, not of controlled testing.

What does Xiao Feng San help with?

• Atopic dermatitis (eczema): This is the best-studied use, and the evidence is still thin. A small randomised, double-blind, placebo-controlled trial in Taiwan in people with refractory atopic dermatitis reported improvements in rash severity, itch and quality of life over several months of granule treatment, with acceptable tolerability. Beyond that, most supporting studies are small, unblinded, Chinese-language, and often combine the formula with topical steroids — which makes it hard to separate the herbs from the conventional treatment. Reasonable to trial alongside standard care under a practitioner; not a substitute for it.
• Chronic urticaria (hives): Chronic urticaria is one of the formula's traditional indications and a common real-world prescription in Chinese and Taiwanese clinics, usually alongside antihistamines. Clinical testing is weaker here than for eczema: mostly small trials of variable quality, frequently comparing herbs plus antihistamine against antihistamine alone, with inconsistent outcome measures. Some report faster itch relief and fewer relapses; the risk of bias is high. If your hives have lasted more than six weeks you need a medical assessment first — chronic urticaria has treatable drivers and effective conventional options.
• Acute urticaria and heat-aggravated rashes: Traditional practice uses Xiao Feng San for hives and itchy eruptions that flare with heat, sweating, alcohol or spicy food — a picture that matches its "wind-damp-heat" indication closely. There is essentially no controlled human trial evidence specific to acute urticaria; this rests on the traditional record and clinical custom. Acute hives usually settle on their own or with antihistamines, and any hives accompanied by lip or tongue swelling, wheeze or faintness is a medical emergency, not something to manage with herbs.
• Contact and irritant dermatitis: Used traditionally for red, hot, itchy, oozing patches following contact with an irritant or allergen. The supporting evidence is traditional use plus animal models of allergic contact dermatitis, in which the extract reduces ear swelling and inflammatory markers. No meaningful human trial data exists for this indication. The most effective step for contact dermatitis remains identifying and removing the trigger; herbs address the symptoms at best.
• Generalised itch (pruritus): Itch is the symptom the formula is aimed at, and it is the outcome patients most often report changing first in the available trials. However, generalised itch without a rash can signal liver, kidney, thyroid or haematological disease, and occasionally lymphoma. Persistent unexplained itch warrants blood tests and a doctor's assessment before self-treating. Where a cause has been excluded, this formula is a reasonable practitioner-guided option, with the caveat that the evidence is traditional rather than trial-based.

What can Xiao Feng San help prevent?

• Nothing is proven to be prevented by this formula. Traditionally it is used to reduce the frequency of itchy flares in people whose eczema or urticaria worsens in heat and humidity, but no controlled trial has tested it as a preventive.
• Scratch–itch cycle damage — by reducing itch it may indirectly limit skin breakdown and secondary infection, though this has not been measured as a study outcome.

Which foods are rich in Xiao Feng San?

Traditional advice while taking Xiao Feng San is to avoid the things said to aggravate "damp-heat" skin: alcohol, chilli and heavily spiced food, deep-fried food, and — in classical texts — shellfish and strong-flavoured meats. That advice is not trial-tested, but it overlaps with what many people with urticaria notice themselves, since alcohol and heat genuinely lower the itch threshold. Foods worth emphasising for skin generally: oily fish (salmon, mackerel, sardines) for omega-3s; a wide range of vegetables and fruit for polyphenols; fermented foods such as kefir and live yoghurt, since some trials of probiotics in eczema show modest benefit; and plenty of water. Because the formula contains licorice, keep an eye on total salt intake and avoid separate licorice confectionery, licorice tea or other licorice-containing herbal products while you are taking it — the effects add up. If you have identified a specific food trigger for your hives, avoiding it will do more than any herb.

What are the side effects of Xiao Feng San?

• Stomach discomfort, nausea or reduced appetite: the bitter, cold herbs (Sophora flavescens, gypsum, anemarrhena) are the usual cause
• Loose stools or mild diarrhoea, especially in people with an already weak digestion
• Pseudoaldosteronism from the licorice with prolonged use: low potassium, raised blood pressure, ankle swelling, muscle weakness or cramps — uncommon but well documented with licorice-containing Kampo formulas
• Rare liver enzyme elevations; stop and seek medical advice if you develop jaundice, dark urine, right-sided abdominal pain or unusual fatigue
• Rare allergic reactions, including rash: note that cicada moulting is an insect-derived ingredient
• Rare interstitial pneumonia and liver injury have been reported across Kampo formulas generally; see a doctor for new persistent dry cough, breathlessness or fever

Good to know:

Short courses in healthy adults are generally well tolerated, and the Taiwanese placebo-controlled trial reported no serious adverse events. The two things to take seriously are the licorice (monitor blood pressure and potassium if you use it for months) and the source of the mu tong ingredient — buy only from regulated GMP manufacturers so you are not exposed to Aristolochia.

How much Xiao Feng San should you take?

• Recommended daily: Granulated extract (Kampo Shofusan or equivalent TCM concentrate): typically 7.5 g of granules per day, divided into two or three doses; some Chinese-style concentrates are dosed at 6–9 g/day. Raw-herb decoction: a single day's decoction of the classical formula, drunk in two portions — proportions vary by practitioner and are usually adjusted to the individual. Doses for children are weight-adjusted and should be set by a qualified practitioner, not scaled at home.
• Best time of day: Split across the day — traditionally morning, midday and evening. No advantage to night-time dosing; it is not sedating.
• With or without food: Kampo convention is to take granules before or between meals with warm water. If the bitter herbs upset your stomach — common with Sophora flavescens and gypsum — taking it just after food is a reasonable trade-off for tolerability.
• Time to effect: Itch intensity may shift within 1–2 weeks. Visible change in the skin generally takes 4–8 weeks, and the trial evidence used treatment periods of several months.
• How long to take it: Usually reviewed at 4–8 weeks. Because of the licorice content, courses running beyond about 8–12 weeks should include blood pressure checks and a potassium test, and the prescription is often modified for long-term use. Stop and reassess if there is no benefit by 8 weeks.