Herbsmith Rx Bu Fei Tang is a classical Chinese herbal formula recommended by holistic veterinarians to augment the qi, nourish the yin, stabilize the exterior, and support lung and kidney function in dogs, cats, and horses. Also known as Ginseng and Aster, Tonify the Lungs Pill, and Restore the Lung, Bu Fei Tang is a six-herb formula that addresses the combined pattern of lung qi and yin vacuity with kidney yin insufficiency and an unstabilized exterior - a pattern in which the lung's weakened qi fails to govern respiration and diffuse the defensive qi to the body surface, while concurrent yin vacuity deprives the lung of the moistening it requires to descend and clear, generating the characteristic combination of chronic respiratory difficulty, spontaneous sweating from an unguarded exterior, dry or unproductive respiratory changes, and constitutional fatigue. The formula's six herbs address this combined pattern from four simultaneous directions: powerfully tonifying the lung qi and yuan qi from the constitutional level (Ren Shen); augmenting the qi, raising the yang, and strengthening the exterior's defensive capacity (Huang Qi); nourishing the yin and blood and replenishing the kidney essence that provides the constitutional yin foundation for lung moistening (Shu Di Huang); astringing the lung qi and preventing its dissipation while generating fluids and nourishing the kidney yin (Wu Wei Zi); moistening the lung and transforming accumulated phlegm that yin vacuity and qi weakness have failed to move (Zi Wan); and clearing residual lung heat that yin vacuity generates while descending the lung qi and supporting fluid metabolism (Sang Bai Pi). Well suited for dogs, cats, and horses presenting with lung qi and yin vacuity, characterized by chronic fatigue and general debility from qi vacuity failing to energize the body; respiratory difficulty, labored breathing, or reduced exercise tolerance from lung qi vacuity failing to govern respiration; spontaneous sweating or an easily penetrated exterior from lung qi vacuity failing to diffuse the wei qi to the body surface; dry, unproductive, or chronic respiratory changes from lung yin vacuity failing to moisten the lung and airways; low back weakness or reduced vitality from kidney yin vacuity failing to provide the constitutional yin foundation; and a pale or pale-red tongue with little coating and a weak, fine, or frail pulse in the lung and kidney positions reflecting the qi and yin vacuity. Available as a concentrated powder mixed into food; dogs and cats use the Canine Blend, while horses use the Equine/Horse Blend. Dosing varies by species and body weight, and your authorizing veterinarian will provide specific guidance.
VETERINARY AUTHORIZATION REQUIRED: Submit Your Authorization Request or Request a TCVM Telemedicine Consultation
What It Supports
- Lung qi and yuan qi tonification through Ren Shen as the principal qi tonic powerfully augmenting the lung qi from the yuan qi level, generating fluids, and calming the spirit disturbed by qi vacuity: Powerfully tonifies the lung qi and yuan qi (source qi), generates fluids, calms the spirit, and strengthens the spleen and stomach's qi-generating function through Ren Shen (ginseng root, Ginseng Radix), the formula's chief herb and the classical materia medica's most important single herb for qi vacuity with fluid insufficiency. Ren Shen's sweet, slightly bitter, and slightly warm nature enters the lung, spleen, and heart channels to tonify the qi from the deepest constitutional level - the yuan qi level, where the source qi that powers all organ function is generated and stored - providing the most substantial and sustained qi replenishment in the formula. In Bu Fei Tang's therapeutic architecture, Ren Shen addresses the lung qi vacuity at its constitutional root: the lung qi's capacity to govern respiration, diffuse the defensive qi, and descend the qi depends on a sufficient supply of yuan qi from the kidney and spleen to supplement the lung's function, and when this constitutional qi supply is insufficient, the lung's governing function progressively fails. Ren Shen also generates fluids from the qi level, addressing the fluid insufficiency that accompanies qi vacuity and providing the initial moistening support for the lung yin vacuity that Shu Di Huang, Wu Wei Zi, and Sang Bai Pi address more directly. Ren Shen has significant interaction potential: it has mild stimulant effects on the central nervous system and adrenal axis (ginsenoside content) and has well-documented interactions with warfarin (anticoagulant effect modulation), MAO inhibitors, and hypoglycemic medications; veterinary coordination is required before use in animals on these medications.
- Qi augmentation, exterior stabilization, and defensive qi strengthening through Huang Qi tonifying the lung qi and spleen qi from the surface and interior simultaneously, raising the yang to the body surface, and strengthening the wei qi's capacity to guard the exterior: Tonifies the lung qi and spleen qi, raises the yang, strengthens and stabilizes the exterior by augmenting the wei qi's defensive capacity, and promotes the healing of the body surface through Huang Qi (astragalus root, Astragali Radix), the formula's primary exterior-stabilizing and qi-augmenting herb and the classical materia medica's most important single herb for qi vacuity with an unstabilized, easily penetrated exterior. Huang Qi's sweet and slightly warm nature enters the lung and spleen channels to tonify the qi from two simultaneous directions: from the spleen and middle jiao upward (raising the yang and supplementing the source of qi generation) and outward to the body surface (augmenting the wei qi that the lung diffuses to guard the exterior). In Bu Fei Tang, Huang Qi works with Ren Shen to address the qi vacuity from complementary angles: Ren Shen tonifies the qi from the deep constitutional and yuan qi level, while Huang Qi tonifies and raises the qi to the exterior and surface level, ensuring the restored qi reaches the body surface where the lung's wei qi-diffusing function operates. The combination of Ren Shen and Huang Qi for lung qi vacuity with exterior weakness is one of the most foundational qi-tonifying pairs in classical TCVM. Huang Qi has immunomodulatory effects from its polysaccharide content; monitoring is warranted in animals on immunosuppressive medications where Huang Qi's immune-augmenting action could counteract the medication's immunosuppressive intent.
- Yin and blood nourishment and kidney essence replenishment through Shu Di Huang providing the constitutional yin and blood foundation that the lung requires for moistening and that the kidney requires as the constitutional yin root of all organ yin: Nourishes the yin and blood, replenishes the kidney essence, and provides the constitutional yin foundation from which the lung's moistening function is sustained through Shu Di Huang (prepared rehmannia root, Rehmanniae Radix preparata), the formula's primary yin-nourishing herb and the classical materia medica's most important single herb for the combined kidney and lung yin vacuity pattern. Shu Di Huang's sweet, slightly warm, and heavy nature enters the liver, kidney, and heart channels at the essence level to replenish the kidney essence (jing) - the deepest constitutional yin in the TCVM hierarchy - from which the lung yin is sustained through the lung-kidney yin relationship: the kidney is the constitutional root of all organ yin, and when kidney yin is insufficient, the lung loses the constitutional yin nourishment it receives from the kidney through the generating cycle, aggravating the lung yin vacuity. In Bu Fei Tang, Shu Di Huang's substantial yin-nourishing action provides the deep constitutional yin replenishment that the lung's moistening function ultimately depends upon, complementing Wu Wei Zi's astringing and fluid-generating action (which conserves the yin already present) and Sang Bai Pi's heat-clearing action (which addresses the vacuity heat that yin insufficiency generates). Shu Di Huang's heavy, cloying nature warrants caution in animals with significant dampness, phlegm, or spleen qi weakness.
- Lung qi astringing, fluid generation, and kidney yin nourishment through Wu Wei Zi containing the five flavors to astringently secure the lung qi that vacuity is failing to hold, generate fluids to moisten the dryness of yin vacuity, and nourish the kidney yin from the sour-astringing direction: Astringes the lung qi, generates fluids, nourishes the kidney yin, calms the spirit, and secures the dissipating qi through Wu Wei Zi (schisandra berry, Schisandrae Fructus), the formula's astringing and fluid-generating herb whose unique five-flavor nature (sour, bitter, sweet, acrid, salty - containing all five flavors) allows it to act simultaneously on all five organ systems while primarily exerting its sour-astringing action on the lung and kidney. Wu Wei Zi's primary action in Bu Fei Tang is threefold: first, it astringently secures the lung qi that vacuity is failing to hold (lung qi vacuity generates a tendency toward qi dissipation and escape, manifesting as labored breathing, spontaneous sweating, and qi leakage from the exterior - Wu Wei Zi's sour-astringing action directly prevents this qi dissipation); second, it generates fluids from the sour-generating direction, providing the immediate fluid and moisture restoration that Shu Di Huang's deep constitutional nourishment supports at the source level; and third, it nourishes the kidney yin from the kidney-astringing direction, supporting Shu Di Huang's kidney essence replenishment with a complementary yin-securing action. Wu Wei Zi's sedative properties from its schisandrin and gomisin lignan content warrant monitoring in animals on sedative and central nervous system-modulating medications. Wu Wei Zi has significant CYP enzyme inhibition potential (primarily CYP3A4 and CYP2C9) from its lignan content; this creates meaningful interaction potential with medications that are metabolized by these enzymes, including cyclosporine, many antibiotics, antifungal medications, and other hepatically metabolized drugs; veterinary review of all current medications is required before use.
- Lung moistening and phlegm transformation through Zi Wan moistening the lung's dry yin-vacuous tissue, descending the lung qi, and transforming the accumulated phlegm that yin vacuity and qi weakness have failed to move and clear: Moistens the lung, descends the lung qi, transforms phlegm, and addresses the accumulation of dry or sticky phlegm that lung yin vacuity and qi weakness generate when the lung's moistening function fails and its qi-descending and diffusing function is compromised through Zi Wan (aster root, Asteris Radix), the formula's lung-moistening and phlegm-transforming herb. Zi Wan's bitter, sweet, and slightly warm nature enters the lung channel to moisten the lung tissue from the surface level, addressing the dryness and phlegm accumulation that yin vacuity generates directly in the lung's mucosal tissues - complementing Shu Di Huang's deep constitutional yin nourishment (which restores the yin from the kidney-essence level upward) with a more direct lung-surface moistening action. In the classical materia medica, Zi Wan is one of the most important herbs for chronic lung conditions with phlegm accumulation because it moistens and descends the lung qi simultaneously: while many phlegm-transforming herbs are drying and could aggravate the yin vacuity, Zi Wan's moistening nature ensures the phlegm is transformed and moved without further depleting the lung's yin. Zi Wan is generally well tolerated; its warm nature warrants monitoring in animals with significant lung heat or yin vacuity heat patterns where the warming action could exacerbate the heat.
- Lung heat clearing and fluid metabolism support through Sang Bai Pi draining the lung heat that yin vacuity generates and has allowed to accumulate, descending the lung qi, and supporting the lung's fluid-metabolizing function through the urinary pathway: Drains lung heat, descends the lung qi, promotes urination, and addresses the vacuity heat and fluid accumulation that lung yin insufficiency and qi vacuity generate through Sang Bai Pi (white mulberry root bark, Mori Cortex), the formula's heat-clearing and lung-descending herb that provides the cooling and descending counterbalance to the formula's predominantly warming and tonifying herbs. Sang Bai Pi's sweet and cold nature enters the lung channel to drain the heat that has accumulated in the lung from yin vacuity - when lung yin is insufficient, the relative excess of yang generates vacuity heat that further consumes the lung yin in a self-perpetuating cycle; Sang Bai Pi clears this vacuity heat directly, interrupting the cycle and protecting the lung yin from further heat-induced consumption. Sang Bai Pi also descends the lung qi, supporting the lung's governing function and ensuring the qi flows downward as intended rather than rebelling upward as lung qi vacuity and heat accumulation can cause. Sang Bai Pi promotes urination, supporting the lung's role in fluid metabolism through the lung-kidney water metabolism relationship and addressing the fluid accumulation that compromised lung qi-descending and diffusing function can generate. Sang Bai Pi's cold nature warrants caution in animals with significant spleen yang vacuity or cold patterns where the cooling action could further compromise the middle jiao's warming function.
TCVM Principles
- Primary action - lung qi and yin vacuity with kidney yin insufficiency and exterior instability through the combined strategy of tonifying the lung qi from the constitutional level (Ren Shen, Huang Qi), nourishing the yin and kidney essence (Shu Di Huang, Wu Wei Zi), moistening and clearing the lung (Zi Wan, Sang Bai Pi), and astringing the dissipating qi (Wu Wei Zi): Addresses the lung qi and yin vacuity pattern with kidney yin insufficiency and unstabilized exterior through four simultaneous therapeutic strategies that correspond to the four most clinically significant aspects of the Bu Fei Tang pattern. Constitutional qi tonification (Ren Shen, Huang Qi) addresses the lung's weakened governing and diffusing function at its source. Yin and essence nourishment (Shu Di Huang, Wu Wei Zi) addresses the lung's loss of moistening from the deep constitutional yin level upward. Lung surface moistening and phlegm transformation (Zi Wan) addresses the accumulated dryness and phlegm in the lung tissue directly. Lung heat clearing and qi descending (Sang Bai Pi) addresses the vacuity heat and rebellious qi that yin insufficiency and qi vacuity generate. The formula's astringing component (Wu Wei Zi, working together with Huang Qi's exterior-stabilizing action) addresses the exterior instability and qi leakage that lung qi vacuity generates at the body surface.
- Secondary action - the distinction between the lung qi and yin vacuity pattern of Bu Fei Tang and pure lung qi vacuity (without the yin vacuity and kidney involvement requiring Shu Di Huang and Wu Wei Zi), pure lung yin vacuity (without the qi vacuity and exterior instability requiring Ren Shen and Huang Qi), or wind-cold or wind-heat invasion of the lung (excess patterns requiring releasing exterior herbs rather than tonification): Bu Fei Tang is indicated specifically for the combined lung qi and yin vacuity pattern with kidney yin insufficiency and exterior instability from qi vacuity failing to diffuse the defensive qi, not for pure excess lung patterns (wind-cold or wind-heat invasion, lung phlegm-heat excess, or lung fluid retention from yang vacuity) or for pure yin vacuity without the qi vacuity component. The clinical differentiation centers on the characteristic combination of qi vacuity signs (fatigue, weak pulse, labored breathing, spontaneous sweating) with yin vacuity signs (dry changes, pale-red tongue with little coating, fine pulse) without the excess signs (thick tongue coating, floating or strong pulse, acute onset) that characterize the excess lung patterns. Your authorizing veterinarian will confirm the combined Lung Qi and Yin Vacuity pattern through tongue and pulse examination and clinical assessment.
Available Forms
- Powder - Canine Blend (for dogs and cats): Available in 75 g, 150 g, 500 g, 900 g, and 1200 g sizes; mix into food at the recommended dose for your pet's weight. Cats and dogs both use this blend.
- Powder - Equine/Horse Blend (for horses only): Available in 150 g, 500 g, 900 g, and 1200 g sizes; mix into grain at the recommended dose for your horse.
Suggested Use
For Dogs (Canine Blend Powder):
- Under 30 lbs: ½ tsp twice daily, or as prescribed
- 30-80 lbs: 1 tsp twice daily, or as prescribed
- 80-120 lbs: 1½ tsp twice daily, or as prescribed
- Over 120 lbs: 2 tsp twice daily, or as prescribed
For Cats (Canine Blend Powder): ¼ tsp twice daily, or as prescribed
For Horses (Equine/Horse Blend, 1,000 lb horse): Two tablespoons twice daily for 20 days, then two tablespoons once daily in grain. If the horse initially refuses, start with a small amount mixed into grain and gradually increase until the horse is accustomed to the taste. Most horses will readily accept the herbs in their grain.
Ingredients
Active Ingredients: Ren Shen (Ginseng Radix), Huang Qi (Astragali Radix), Shu Di Huang (Rehmanniae Radix preparata), Wu Wei Zi (Schisandrae Fructus), Zi Wan (Asteris Radix), Sang Bai Pi (Mori Cortex)
Inactive Ingredient: Flaxseed
VETERINARY AUTHORIZATION REQUIRED: Submit Your Authorization Request or Request a TCVM Telemedicine Consultation
Active Ingredient TCVM Actions
Bu Fei Tang is a six-herb formula organized around four therapeutic strategies: constitutional qi tonification (Ren Shen, Huang Qi), yin and essence nourishment with qi astringing (Shu Di Huang, Wu Wei Zi), lung moistening and phlegm transformation (Zi Wan), and lung heat clearing with qi descending (Sang Bai Pi):
- Ren Shen (Ginseng Radix) - Asian Ginseng Root: Powerfully tonifies the lung qi and yuan qi from the constitutional level, generates fluids, calms the spirit, and strengthens the spleen's qi-generating function; the formula's chief herb and the most important single herb for constitutional qi vacuity with fluid insufficiency. Ren Shen has significant interaction potential with warfarin, MAO inhibitors, and hypoglycemic medications; veterinary coordination required before use in animals on these medications.
- Huang Qi (Astragali Radix) - Astragalus Root / Milk Vetch Root: Tonifies the lung qi and spleen qi, raises the yang to the body surface, strengthens and stabilizes the exterior by augmenting the wei qi's defensive capacity, and promotes healing of the body surface; the formula's primary exterior-stabilizing herb working with Ren Shen to address the qi vacuity from the surface and constitutional levels simultaneously. Immunomodulatory effects from polysaccharide content; monitoring warranted in animals on immunosuppressive medications.
- Shu Di Huang (Rehmanniae Radix preparata) - Prepared Rehmannia Root: Nourishes the yin and blood, replenishes the kidney essence, and provides the constitutional yin foundation from which the lung's moistening function is sustained through the lung-kidney yin relationship; the formula's primary yin-nourishing herb addressing the kidney yin insufficiency that deprives the lung of its constitutional yin nourishment. Heavy, cloying nature warrants caution in animals with significant dampness or spleen qi weakness.
- Wu Wei Zi (Schisandrae Fructus) - Schisandra Berry / Five-Flavor Berry: Astringes the lung qi to prevent dissipation, generates fluids to moisten the yin-vacuous lung, nourishes the kidney yin, and calms the spirit; unique five-flavor nature allows simultaneous action on all five organ systems while primarily exerting sour-astringing action on the lung and kidney. Significant CYP3A4 and CYP2C9 enzyme inhibition potential from lignan content creates meaningful interaction risk with cyclosporine, many antibiotics, antifungals, and other hepatically metabolized drugs; veterinary review of all current medications required before use.
- Zi Wan (Asteris Radix) - Purple Aster Root / Tatarian Aster Root: Moistens the lung tissue from the mucosal surface level, descends the lung qi, and transforms accumulated phlegm without the drying action that most phlegm-transforming herbs would impose on the already yin-vacuous lung; addresses the dryness and phlegm accumulation of yin vacuity directly in the lung's tissue. Generally well tolerated; warm nature warrants monitoring in animals with significant lung heat or yin vacuity heat.
- Sang Bai Pi (Mori Cortex) - White Mulberry Root Bark: Drains lung heat generated by yin vacuity, descends the lung qi, and promotes urination to support the lung's fluid-metabolizing function; provides the cooling and descending counterbalance to the formula's predominantly warming and tonifying herbs, clearing vacuity heat and interrupting the cycle of heat further consuming the lung yin. Cold nature warrants caution in animals with significant spleen yang vacuity or cold patterns.
Potential Drug Interactions
Bu Fei Tang has two primary drug interaction concerns. The first is Wu Wei Zi's significant CYP enzyme inhibition: its schisandrin and gomisin lignan content inhibits CYP3A4 and CYP2C9 enzymes, creating meaningful interaction potential with any medication metabolized by these pathways, including cyclosporine, many antibiotics and antifungal medications, anticonvulsants, and other hepatically metabolized drugs. This interaction can substantially increase the blood levels and duration of action of these medications. The second is Ren Shen's interaction with warfarin (both potentiation and inhibition have been reported depending on the preparation and dose), MAO inhibitors (potential for hypertensive crisis), and hypoglycemic medications (Ren Shen has mild hypoglycemic effects that can compound the medication's action). Huang Qi's immunomodulatory effects create a third interaction concern in animals on immunosuppressive medications such as cyclosporine, corticosteroids, and chemotherapy, where Huang Qi's immune-augmenting action could counteract the immunosuppressive intent. The formula's heavy yin-nourishing component (Shu Di Huang) warrants caution in animals with significant dampness, phlegm, or spleen yang vacuity cold.
Medication categories warranting extra caution include anticoagulant medications (Ren Shen warfarin interaction), MAO inhibitors and psychotropic medications (Ren Shen), hypoglycemic medications (Ren Shen mild hypoglycemic effects), immunosuppressive medications (Huang Qi immune-augmenting effects), and any hepatically metabolized medication subject to CYP3A4 or CYP2C9 metabolism (Wu Wei Zi enzyme inhibition). Your authorizing veterinarian will determine appropriateness based on your animal's condition, current medications, and confirmation of the lung qi and yin vacuity pattern through tongue quality (pale or pale-red with little coating), pulse character (weak, fine, or frail in the lung and kidney positions), and clinical assessment of the qi and yin vacuity signs.
VETERINARY AUTHORIZATION REQUIRED: Submit Your Authorization Request or Request a TCVM Telemedicine Consultation
Frequently Asked Questions
What conditions is Bu Fei Tang used for in TCVM?
In Traditional Chinese Veterinary Medicine, Bu Fei Tang is indicated for the combined lung qi and yin vacuity pattern with kidney yin insufficiency and exterior instability. The clinical presentation centers on chronic fatigue and general debility from qi vacuity; respiratory difficulty, labored breathing, or reduced exercise tolerance from lung qi vacuity failing to govern respiration; spontaneous sweating or an easily penetrated exterior from lung qi vacuity failing to diffuse the wei qi; dry or chronic respiratory changes from lung yin vacuity failing to moisten the lung and airways; low back weakness or reduced vitality from kidney yin insufficiency; and a pale or pale-red tongue with little coating and a weak, fine, or frail pulse in the lung and kidney positions. Bu Fei Tang is particularly suited for chronic constitutional lung and kidney vacuity patterns rather than acute excess lung conditions. Your authorizing veterinarian will confirm the pattern through tongue and pulse examination and clinical assessment.
How is Bu Fei Tang administered to dogs, cats, and horses?
Mix the powder directly into food or grain at the dose recommended for your animal's species and body weight. Dogs and cats use the Canine Blend; horses use the Equine/Horse Blend. All species receive the formula twice daily, with horses following the standard 20-day twice-daily loading protocol before transitioning to once-daily maintenance dosing. Because Bu Fei Tang contains Ren Shen (with significant interactions with warfarin, MAO inhibitors, and hypoglycemic medications) and Wu Wei Zi (with significant CYP enzyme inhibition affecting many hepatically metabolized medications), comprehensive veterinary review of all current medications is particularly important before use. The formula's constitutional tonifying and astringing strategy is not appropriate for animals with acute exterior wind invasion, significant excess phlegm-heat in the lung, or significant dampness and spleen yang vacuity.
How long does it take to see results with Bu Fei Tang?
As a formula addressing a chronic constitutional lung qi and yin vacuity pattern, Bu Fei Tang requires a sustained treatment course to meaningfully restore the lung qi and yin. Early improvement in the most responsive signs (reduced spontaneous sweating, mild improvement in energy and exercise tolerance) may be seen within 2 to 4 weeks as the formula's qi-tonifying herbs (Ren Shen, Huang Qi) begin replenishing the lung and wei qi. More substantial restoration of the lung yin and kidney essence, reflected in improved respiratory comfort, reduced dryness, and normalization of the tongue color and coating, typically requires 4 to 8 weeks or longer. Deeply established lung qi and yin vacuity with kidney yin insufficiency from chronic illness, aging, or constitutional depletion may require 3 to 6 months of sustained treatment. Your authorizing veterinarian will monitor tongue, pulse, and clinical signs throughout the treatment course and adjust the formula as the pattern evolves.
Why does Bu Fei Tang include Shu Di Huang (a kidney yin herb) alongside the lung-focused herbs?
Bu Fei Tang includes Shu Di Huang to address the lung-kidney yin relationship that is central to the Bu Fei Tang pattern: in TCVM, the kidney is the constitutional root of all organ yin in the body, and the lung and kidney share a particularly close yin relationship through the lung-kidney generating cycle (the kidney's water element generates and nourishes the lung's metal element from below). When kidney yin is insufficient, the lung loses the constitutional yin nourishment it receives from the kidney through this generating relationship, aggravating the lung yin vacuity from below. By nourishing the kidney essence with Shu Di Huang, Bu Fei Tang addresses lung yin vacuity at its constitutional root rather than only supplementing lung yin directly. Wu Wei Zi reinforces this lung-kidney relationship from the astringing direction, securing both the lung qi (from dissipating at the surface) and the kidney yin (from leaking downward), making the combination of Shu Di Huang and Wu Wei Zi a particularly important paired strategy for the combined lung-kidney yin vacuity pattern that Bu Fei Tang addresses.