Best Chinese Herbs to Boost the Immune System in Flu Season

By Dr (TCM) Attilio D'Alberto | Traditional Chinese Medicine Practitioner, Wokingham

The best Chinese herbs for boosting the immune system in flu season are Huang Qi (Astragalus), Bai Zhu (Atractylodes) and Fang Feng (Saposhnikovia) — together they form the classical preventive formula Yu Ping Feng San (the Jade Windscreen Powder), used in China for over 700 years to strengthen the body's protective shield against colds, flu and respiratory infection. Chinese herbal medicine takes a fundamentally different approach to immunity than western medicine: rather than reacting once an infection is established, it builds the body's Wei Qi (Defensive Qi) over the weeks before flu season so that pathogens are repelled at the surface and never reach the deeper organs. This article covers the top 12 immune-boosting Chinese herbs, the classical formula that combines the three most important of them, when to start taking them, the modern research that supports them, and the dietary and lifestyle support that makes herbs work better.

On this page

1. Overview — immunity in Chinese medicine
2. Wei Qi (Defensive Qi) — the body's protective shield
3. The top 12 immune-boosting Chinese herbs
4. The Jade Windscreen Formula (Yu Ping Feng San)
5. Other classical immune formulas
6. Modern research on immune-modulating herbs
7. When to start, how long to take them
8. Diet and lifestyle to support immunity
9. Cautions and contraindications
10. Bespoke prescriptions at my clinic
11. Frequently asked questions

1. Overview — immunity in Chinese medicine

Chinese medicine has been treating respiratory infection for over 2,000 years. The classical texts — from the Shang Han Lun (Treatise on Cold Damage, c. 220 CE) to the Wen Bing (Warm Disease) school of the Qing dynasty — describe in remarkable detail how external pathogens invade the body, the stages of infection, and the herbal strategies for both treatment and prevention. The accumulated knowledge informs a precise, pattern-based approach that does not see immunity as a single immune system in the western sense, but as a coordinated set of organ functions — principally Lung, Spleen and Kidney — that together produce and circulate the body's Wei Qi, the protective layer at the body surface.

The principal preventive strategy in TCM is to strengthen the body before flu season starts rather than waiting for symptoms. The classical Chinese physician would start a patient on immune-tonifying herbs in late autumn, well before the worst of the cold weather and the flu peak, so that by the time the seasonal pathogens were circulating the patient's defensive layer was strong enough to repel them. This is exactly the kind of preventive medicine that modern healthcare has largely lost sight of, and it is one of the most clinically valuable contributions Chinese herbal medicine makes to general wellbeing.

2. Wei Qi (Defensive Qi) — the body's protective shield

The concept of Wei Qi (卫气, literally “protective qi” or “defensive qi”) is central to the TCM understanding of immunity. Wei Qi is a fast-flowing, warming, defensive layer of qi that circulates just below the skin during the day and retreats inward during sleep. It has three primary functions:

1. Protects the body surface from invasion by external pathogens — wind, cold, heat, damp and dryness in TCM terms; viruses, bacteria, fungi and allergens in modern terms
2. Regulates the opening and closing of the pores — sweating to release heat, closing to retain warmth
3. Warms the skin, muscles and organs and supports their normal function

Wei Qi is produced primarily by the Spleen (the “root of post-heaven qi”), circulated and distributed by the Lung, and ultimately rooted in the Kidney Yang. This means that effective immune support must address all three organ systems — not just one. People with weak Wei Qi are typically prone to recurrent colds and flu, slow to recover, sensitive to draughts and cold weather, susceptible to seasonal allergies, and may sweat easily without exertion (a sign that the pores are not closing properly). These are exactly the patients who benefit most from herbal immune support — the “always catches it from the children” parent, the “every winter brings two colds” office worker, the recurrent post-viral fatigue patient.

3. The top 12 immune-boosting Chinese herbs

The Chinese materia medica contains hundreds of herbs with immune-modulating action. The twelve below are the most clinically important and the most likely to appear in a modern preventive prescription. They are ordered roughly by importance and frequency of use.

1. Huang Qi (Astragalus / Astragali Radix)

The single most important immune-tonifying herb in the Chinese materia medica. Huang Qi tonifies the Spleen and Lung qi, raises sunken qi, and is the principal herb for strengthening Wei Qi. Modern research has documented immunostimulant, antiviral, anti-inflammatory and antioxidant activity, with active polysaccharides and astragalosides enhancing NK cell, macrophage and T-cell function. Huang Qi is the imperial herb of Yu Ping Feng San and is also used in convalescence, recurrent infection and post-viral fatigue. Western herbalism has adopted Astragalus extensively for the same indications.

2. Bai Zhu (White Atractylodes / Atractylodis Macrocephalae Rhizoma)

The most important Spleen-strengthening herb in the materia medica. Bai Zhu tonifies Spleen qi, dries dampness and stabilises the exterior — the combined effect is to build the production of Wei Qi at its source. It pairs with Huang Qi in Yu Ping Feng San. Modern research shows immunomodulatory effects on lymphocyte function, alongside well-documented benefits for digestive function, fluid metabolism and fatigue.

3. Fang Feng (Saposhnikovia / Saposhnikoviae Radix)

The name literally means “guard against wind”. Fang Feng releases the exterior, expels wind, and (in combination with Huang Qi and Bai Zhu) closes the pores to prevent pathogen entry. It is the third herb of Yu Ping Feng San and the only one of the three that is also actively pathogen-dispelling. Useful for those whose immune weakness manifests with cold-sensitivity, draughts and frequent acute wind-cold colds.

4. Ling Zhi (Reishi mushroom / Ganoderma)

The classical “mushroom of immortality” in Chinese medicine. Ling Zhi nourishes the Heart, calms the Shen and tonifies qi while exerting a powerful adaptogenic and immunomodulatory effect. Modern research has documented enhancement of NK cell activity, T-cell function and antibody production, alongside anti-inflammatory, antioxidant, anti-cancer and anti-fatigue effects. Particularly suited to immune support in patients with comorbid anxiety, insomnia or chronic stress. See also medicinal mushrooms benefits.

5. Dong Chong Xia Cao (Cordyceps / Ophiocordyceps sinensis)

The classical Lung and Kidney yang tonic. Cordyceps nourishes the Lung, supplements the Kidney, augments athletic performance and immune function. It is particularly suited to patients with recurrent respiratory infection, post-viral fatigue and chronic lung disease, and to active patients who want immune support that also benefits stamina. Modern research documents immunomodulation, anti-inflammatory and adaptogenic effects.

6. Dang Shen (Codonopsis / Codonopsis Pilosulae Radix)

A gentler, less expensive substitute for ginseng in many qi-tonifying formulas. Dang Shen tonifies the Spleen and Lung qi, builds blood and is particularly well-suited to chronic constitutional qi weakness with recurrent infections. Suitable for long-term daily use, including in children.

7. Ginseng (Ren Shen / Panax Ginseng Radix)

The most famous tonic herb in the Chinese materia medica. Ren Shen powerfully tonifies the original qi (Yuan Qi), Spleen, Lung and Heart, generates fluids and calms the Shen. Modern research has documented strong immunomodulation, increased NK cell activity, anti-fatigue and adaptogenic effects from the ginsenosides. Best reserved for marked deficiency with clear cold signs — for routine immune support, Dang Shen or Huang Qi are usually a better fit. Xi Yang Shen (American ginseng) is the cooler alternative for Yin-deficient or heat-sensitive patients.

8. Wu Wei Zi (Schisandra / Schisandrae Fructus)

The “five-flavour fruit”, named for combining all five tastes (sour, bitter, sweet, pungent and salty) in a single berry. Schisandra is a classical adaptogen, tonifying the Lung and Kidney qi, calming the Shen and astringing leakage. Particularly suited to immune support in chronic stress, insomnia and respiratory weakness; widely used in modern Russian and Chinese sports medicine for stamina and recovery.

9. Gan Cao (Liquorice root / Glycyrrhizae Radix)

The most frequently used herb in the entire Chinese materia medica. Gan Cao tonifies qi, harmonises the actions of other herbs in a formula, and clears heat and toxin. Modern research has demonstrated antiviral activity (notably against influenza viruses and SARS-CoV-2 in vitro), immunomodulation and corticosteroid-like anti-inflammatory effects via glycyrrhizin. Almost always present in classical immune-boosting and respiratory-protective formulas.

10. Da Zao (Chinese jujube / Ziziphi Jujubae Fructus — red dates)

A sweet, gentle qi and blood tonic that calms the Shen and harmonises the formula. Da Zao is rich in polysaccharides with documented immune-enhancing activity and is a staple of every-day Chinese kitchens for both food therapy and herbal support. Particularly suited to children, the elderly and patients whose immune weakness coexists with anaemia, fatigue or anxiety.

11. Gou Qi Zi (Goji berries / Lycii Fructus)

The classical tonic for Liver and Kidney yin and one of the easiest immune-supportive herbs to incorporate into daily life — eaten as dried berries, brewed as tea or added to soups. Modern research documents NK cell activation, antioxidant and anti-fatigue effects. A particularly good choice for the immune support of older adults, eye strain and the increasingly common pattern of stressed Yin-deficient overworking patients.

12. Ban Lan Gen (Isatis root / Isatidis Radix)

The classical Chinese antiviral herb. Ban Lan Gen clears heat, resolves toxin and is widely used in modern Chinese clinical practice for the prevention and early treatment of viral respiratory infections including influenza, mumps and SARS-family viruses. In flu season it is often added to preventive prescriptions or used as a short course at the very first signs of an acute infection. Unlike the long-term tonics above, Ban Lan Gen is used for short-course immune-supportive purposes — not as a daily preventive over months.

4. The Jade Windscreen Formula (Yu Ping Feng San)

Yu Ping Feng San (玉屏风散) — literally “Jade Windscreen Powder” — is the single most important preventive formula in Chinese medicine for vulnerability to recurrent colds, flu and respiratory infection. Recorded in the Dan Xi Xin Fa (Master Danxi's Mind Method, c. 1481), it has been used continuously for over 500 years and is one of the best-researched of the classical formulas. The composition is elegantly simple:

• Huang Qi (Astragalus) — the imperial herb; tonifies Spleen and Lung qi and stabilises the exterior
• Bai Zhu (White Atractylodes) — tonifies Spleen qi and supports the production of Wei Qi
• Fang Feng (Saposhnikovia) — closes the pores and dispels lingering wind

The image embedded in the name is striking: Huang Qi and Bai Zhu build a strong screen at the body surface (the jade); Fang Feng makes the screen flexible enough to release wind when needed without letting pathogens in. The result is a body surface that is neither rigidly closed (which causes overheating and trapped pathogens) nor leaky (which lets pathogens in). It is, in TCM terms, the perfect preventive formula.

Modern research has documented immune-modulating effects including enhanced T-cell and B-cell function, increased serum IgA and IgG, increased phagocytic activity of macrophages, and reduced incidence of upper respiratory infections in controlled trials. A meta-analysis of clinical trials of modified Yu Ping Feng San for the prevention of recurrent respiratory infections in children showed significant reductions in infection frequency over follow-up periods of three to six months. The formula is suitable for daily use throughout the autumn-winter season for any patient with the characteristic Wei Qi deficiency pattern.

5. Other classical immune formulas

Yu Ping Feng San is the principal preventive formula, but several other classical formulas serve specific immune-supportive roles. A qualified Chinese herbalist selects between them based on the patient's individual pattern.

• Bu Zhong Yi Qi Tang (Tonify the Middle and Augment Qi Decoction) — for chronic Spleen-Lung qi deficiency with recurrent infection, fatigue, prolapse and bearing-down sensations. Stronger than Yu Ping Feng San for marked qi deficiency
• Yin Qiao San (Honeysuckle and Forsythia Powder) — for the first signs of a wind-heat cold or flu (sore throat, mild fever, headache, thirst). Used at the very onset of acute illness rather than as a daily preventive
• Gui Zhi Tang (Cinnamon Twig Decoction) — for the wind-cold cold with mild fever, chills, sweating and a runny nose. Also used at acute onset
• Sang Ju Yin (Mulberry Leaf and Chrysanthemum Decoction) — for mild wind-heat with prominent cough and minimal fever
• Modified Yu Ping Feng San with Ban Lan Gen — the “flu-season special”: the Jade Windscreen base with Ban Lan Gen added during the peak of the flu season for additional antiviral coverage

See the full Chinese medicine for cold and flu guide for the treatment side — what to take once a cold has actually started.

6. Modern research on immune-modulating herbs

The Chinese immune-tonifying herbs are some of the most extensively researched in the materia medica. The active polysaccharides in Huang Qi, Ling Zhi, Dong Chong Xia Cao and Da Zao have well-documented effects on innate immunity — macrophage and NK cell activation, complement activation and cytokine modulation — while saponins from ginseng and astragalus have effects on T-cell maturation, antibody production and the balance between the helper T-cell subsets (Th1, Th2, Th17, T-regs). The combined effect is broadly described as immunomodulation rather than blanket stimulation: under-active immune function is upregulated, over-active immune function (as in autoimmunity) is downregulated, and the balance between innate and adaptive immunity is restored.

Specific findings include: Huang Qi increases IL-2 and IFN-γ production while reducing IL-4, supporting a Th1-mediated antiviral response; Ling Zhi polysaccharides enhance dendritic cell function and antigen presentation; Cordyceps increases macrophage phagocytosis and NK cell cytotoxicity; Gan Cao's glycyrrhizin inhibits viral replication in vitro against multiple influenza strains. Several controlled clinical trials have demonstrated reductions in upper respiratory infection frequency, severity and duration with preventive use of Yu Ping Feng San or similar formulas over three to six months. The evidence base is uneven but the convergence of classical use with biomedically plausible mechanisms is encouraging.

7. When to start, how long to take them

The classical principle is to start preventive immune support in late autumn, before the flu peak, and continue through to early spring. In the UK that means:

1. September-October — ideal time to start a daily preventive formula such as Yu Ping Feng San. The body has time to build up its Wei Qi before the worst of the cold weather
2. November-February — continue daily; the formula may be adjusted in response to early signs of an acute infection
3. March-April — taper down as the weather warms and the flu peak passes
4. Acute use at first signs — if a cold or flu does start, switch to or add an acute-onset formula such as Yin Qiao San (wind-heat) or Gui Zhi Tang (wind-cold) for 3-5 days while reducing or pausing the tonic

For chronically immune-weak patients — those with recurrent infections all year, post-viral fatigue, frequent sinusitis or chronic respiratory disease — longer continuous treatment courses of three to six months are common, with maintenance prescriptions adjusted seasonally.

8. Diet and lifestyle to support immunity

Herbs work better when supported by the right diet and lifestyle. The classical principles align closely with modern evidence:

1. Eat warm, cooked foods — particularly bone broth, congee, soups and stews in autumn and winter. Raw and cold foods weaken the Spleen and reduce Wei Qi production. See Chinese food therapy for detailed guidance
2. Prioritise sleep — aim for sleep before 11pm and 7-8 hours per night. Sleep is when Wei Qi retreats inward to replenish; chronic short sleep is one of the strongest negative predictors of immune function in modern research
3. Stay warm, especially the neck and lower back — the classical entry points for wind-cold are the back of the neck (where the Gallbladder and Bladder channels meet) and the lower back (Mingmen — the Gate of Vitality). Scarves and warm jumpers protect these vulnerable areas
4. Manage stress — chronic stress depletes Spleen qi and produces a Liver-Spleen disharmony that undermines Wei Qi production. Acupuncture, meditation, qi gong and tai chi are all well-documented stress reducers
5. Move regularly but moderately — daily walking, qi gong or tai chi support Wei Qi circulation; excessive intense exercise paradoxically suppresses immune function and increases infection risk
6. Reduce sugar and alcohol — both generate damp-heat in TCM terms, weaken the Spleen and suppress immune function in modern research
7. Hand hygiene and avoid sick contacts when possible — classical TCM physicians already knew to avoid “pestilential qi” (the same concept as germ theory, just expressed differently)

9. Cautions and contraindications

Chinese herbal medicine is safe when prescribed by a qualified practitioner, but the following considerations apply:

• Acute heat or infection — tonic herbs like Huang Qi and Ren Shen should be used cautiously, or paused, during acute febrile infection, where they can “feed the fire”. Switch to or add appropriate heat-clearing herbs instead
• Hypertension — large doses of Gan Cao (liquorice) can raise blood pressure via mineralocorticoid effects; the dose in Yu Ping Feng San is too small to be a concern but stand-alone Gan Cao should be supervised
• Autoimmune disease — immune-stimulating herbs can theoretically worsen autoimmune conditions; in practice, the combined immunomodulatory effect of classical formulas is usually well tolerated, but pattern-matched prescribing is essential. See Chinese medicine for autoimmune disease
• Pregnancy — some herbs (including Ban Lan Gen) are not used in pregnancy; Yu Ping Feng San itself is generally considered safe but prescribing should always be by a qualified practitioner
• Drug interactions — Ren Shen and Huang Qi can interact with warfarin and other anticoagulants; Gan Cao interacts with corticosteroids and digoxin. Always inform your prescriber of any herbal medicines you are taking

As with all Chinese herbal medicine, prescribing should be by a qualified Chinese herbalist (RCHM-registered in the UK). Self-prescription from over-the-counter sources is unlikely to match your specific TCM pattern and may not be effective — or may aggravate the wrong pattern.

10. Bespoke immune support at my clinic

I prescribe bespoke preventive immune formulas at my Wokingham, Berkshire clinic, with online Chinese herbal consultations available throughout the UK and internationally. Each formula is built from the patient's individual TCM pattern: Wei Qi deficiency with cold sensitivity gets a different prescription from Wei Qi deficiency with damp accumulation, post-viral fatigue, or chronic respiratory weakness. Pharmaceutical-grade granules from Sun Ten in Taiwan are tested to the highest international quality and safety standards. The typical preventive course runs from October through to early spring, with the formula adjusted every six to eight weeks in response to seasonal change and any acute episodes that occur during the season.

11. Frequently asked questions

How quickly do immune-boosting Chinese herbs work?

Most patients notice subjective improvements — better energy, better sleep, fewer minor draughts triggering a sniffle — within two to four weeks of starting daily herbs. The measurable reduction in cold and flu frequency emerges over a full season of consistent use. These are tonic herbs, not symptomatic medications: the effect is built up rather than felt immediately.

Can I take Yu Ping Feng San if I have allergies?

Yes — in fact, Yu Ping Feng San is a classical formula for the prevention of allergic rhinitis (hay fever) as well as colds. The same Wei Qi deficiency pattern underlies recurrent infection and seasonal allergies in many patients, and the formula benefits both.

Are Chinese herbs better than vitamin C and zinc?

Different mechanisms. Vitamin C and zinc are valuable for specific aspects of immune function (collagen synthesis, T-cell maturation, viral entry inhibition) and are sensible to maintain at adequate levels. Chinese herbal formulas modulate broader patterns of immune balance — particularly the Th1/Th2 balance, NK cell activity and the antibody response — through multi-target effects of the active polysaccharides and saponins. The two approaches are entirely compatible and many patients use both alongside their seasonal flu vaccination.

Can children take Chinese herbs for immunity?

Yes, with appropriate paediatric adjustments. Children's prescriptions use gentler herbs (Dang Shen rather than Ren Shen; Tai Zi Shen for very small children), lower doses and shorter courses. Yu Ping Feng San is well-tolerated in children and there is a substantial clinical literature on its use for recurrent paediatric respiratory infection.

Should I keep taking the flu vaccine if I'm on Chinese herbs?

Yes — Chinese herbal immune support is complementary to, not a replacement for, conventional vaccination. The vaccine produces specific antibody-mediated immunity against the seasonal strains; the herbs strengthen the broader immune response and reduce the impact of strains the vaccine does not cover. Many of my patients combine both for maximum protection.

What if I do catch a cold or flu while on a preventive formula?

Stop or reduce the tonic, switch to an acute-onset formula appropriate to the pattern (Yin Qiao San for wind-heat with sore throat and thirst, Gui Zhi Tang for wind-cold with chills and clear runny nose), and rest. Once the acute illness resolves, return to the preventive formula. Acute treatment is typically a short 3-7 day course; the preventive formula resumes once symptoms have cleared.

Return to the blog, the Chinese herbal medicine main page or read Chinese medicine for cold and flu for the treatment side.

Prefer to be treated from home? Chinese herbal medicine online consultations are available throughout the UK and worldwide. After a full video consultation, Dr (TCM) Attilio D'Alberto formulates a bespoke herbal prescription and posts your Chinese herbs directly to your door.