The Immune Defense Herb

How andrographolide from Andrographis paniculata blocks NF-κB inflammation, shortens cold duration, and prevents upper respiratory infections — with evidence from multiple randomized controlled trials and meta-analyses

Andrographis (Andrographis paniculata) is a bitter medicinal herb native to South and Southeast Asia that has been used for centuries in Ayurvedic and traditional Chinese medicine — known in Chinese as Chuān Xīn Lián, meaning "thread-heart lotus." It is now one of the best-researched herbal medicines for acute respiratory infections. A systematic review of seven randomized controlled trials found andrographis significantly superior to placebo in relieving cold symptoms, with symptom scores improving by more than 10 points on standardized scales compared to placebo. [1] A larger 2017 meta-analysis confirmed it reduces both symptom severity and illness duration. [2] In a double-blind prevention trial, students taking andrographis through a winter season caught colds at half the rate of those taking placebo — 30% vs. 62%. [4] Its active compound, andrographolide, targets the same core inflammatory pathway that drives most acute infections.

How Andrographis Works

The principal active compound in andrographis is andrographolide, a bicyclic diterpenoid lactone concentrated in the leaves and aerial parts of the plant. It has several well-characterized mechanisms:

NF-κB Inhibition

Andrographolide's most studied action is blocking nuclear factor kappa B (NF-κB), the master transcription factor that coordinates inflammatory responses. [5] When pathogens trigger NF-κB, it switches on genes for pro-inflammatory cytokines — including TNF-α, IL-1β, IL-6, and IL-12 — that cause the fever, soreness, and fatigue associated with infections. Andrographolide covalently binds to a cysteine residue on the NF-κB p50 subunit, blocking its DNA binding and turning down the inflammatory cascade. This is the same pathway targeted by many pharmaceutical anti-inflammatories, but through a distinct mechanism.

Immune Stimulation

Beyond calming inflammation, andrographolide also directly stimulates immune defenses:

Macrophage activation — enhances phagocytic activity (the ability to engulf and destroy pathogens)
Natural killer (NK) cell activity — increases the front-line viral response before adaptive immunity engages
Interferon production — promotes antiviral signaling that slows viral replication across cells
Lymphocyte proliferation — supports T-cell expansion during active infection [5]

This dual action — dampening excessive inflammation while boosting pathogen-clearing capacity — is characteristic of a true immunomodulator rather than a simple immune stimulant.

Antiviral Properties

In laboratory models, andrographolide has shown direct antiviral effects against influenza, respiratory syncytial virus (RSV), and other respiratory pathogens. It appears to inhibit viral entry and intracellular replication independently of its immune effects, adding a complementary layer of antiviral defense. [5]

Dosing and Practical Use

For acute upper respiratory infections (colds, flu):

Most RCTs used 48–200 mg/day of standardized andrographolide content
The Cáceres et al. trial used 1,200 mg/day of dried extract (approximately 48 mg andrographolide) over 5 days [3]
Start at symptom onset; earlier use produces better results
Duration: 5–10 days for acute illness

For prevention during cold and flu season:

The prevention trial used 2 tablets daily of Kan Jang extract (standardized andrographis) for 3 months [4]
Preventive protocols typically run for the winter season

Forms available:

Standardized extracts are most reliable — look for products standardized to 10% andrographolide
Common commercial products include Kan Jang, SHA-10, and KalmCold
Capsules are the most common form; tinctures are available but intensely bitter

Safety notes: Andrographis is well tolerated at therapeutic doses in clinical trials. Adverse events are mild and infrequent — mainly gastrointestinal sensitivity at higher doses. It is not recommended during pregnancy (animal studies suggest uterine effects). It may potentiate anticoagulant medications due to mild platelet inhibition. As with any immune-active herb, caution is warranted with immunosuppressant drugs.

See our Echinacea page for a complementary immune herb with different mechanisms, and our Elderberry page for antiviral evidence from a different herbal family.

Evidence Review

Poolsup et al. 2004 — Systematic Review of RCTs

The Poolsup et al. systematic review [1] published in the Journal of Clinical Pharmacy and Therapeutics analyzed seven randomized controlled trials evaluating andrographis for uncomplicated upper respiratory tract infections.

Key findings:

Andrographis was significantly superior to placebo in reducing overall symptom scores across all included trials
The pooled mean difference in symptom severity scores was 10.85 points (95% CI: 10.36–11.34, p < 0.0001) in favor of andrographis
Individual symptoms showing the most consistent improvement: sore throat, nasal secretion, headache, and fatigue
All included trials used standardized andrographolide preparations, providing dose consistency

The authors concluded that andrographis is a safe and effective treatment for uncomplicated acute upper respiratory tract infection. Limitations noted: most trials were of short duration and conducted in relatively similar populations (mostly Scandinavian and Chilean studies); generalizability to other populations was uncertain at the time.

Hu et al. 2017 — Systematic Review and Meta-Analysis

The Hu et al. 2017 meta-analysis published in PLOS ONE [2] is the largest and most rigorous synthesis of andrographis evidence. It searched both English and Chinese databases through March 2016, capturing trials unavailable in Western literature.

Design and scope:

33 randomized controlled trials included (n=7,175 participants total)
Studies included children and adults across multiple countries
Interventions ranged from andrographis alone to combination formulas including Siberian ginseng (Kan Jang formula)
Primary outcomes: symptom improvement in acute respiratory tract infections, adverse events

Key results:

Andrographis was significantly superior to placebo for overall symptom improvement (standardized mean difference significant, p < 0.001)
Compared to usual care (typically paracetamol/NSAIDs), andrographis showed equivalent or superior symptom relief in several trials
Cough, sore throat, and nasal secretion showed the most consistent and significant improvement
Adverse events were rare and mild across all included trials — gastrointestinal symptoms were the most reported, similar in frequency to placebo groups

The meta-analysis noted high heterogeneity across studies, reflecting differences in preparation, dose, and outcome measurement. Nonetheless, the direction of effect was consistent across trials: andrographis reliably outperformed placebo for symptom relief in acute respiratory infections.

Cáceres et al. 1999 — Dose-Finding RCT

This double-blind, placebo-controlled randomized trial [3] at the Universidad de Chile enrolled 158 adults with naturally acquired common colds and tested standardized andrographis extract (SHA-10) against placebo over 5 days.

Design details:

Treatment: SHA-10 extract, 1,200 mg/day (providing ~48 mg andrographolide) vs. placebo
Outcome measure: visual analogue scale (VAS) self-assessment across 9 symptom domains
Assessment points: day 0, day 2, and day 4

Results:

By day 2, the andrographis group showed statistically significant reductions in tiredness, sleeplessness, sore throat, and nasal secretion compared to placebo
By day 4, the effect was significant across all measured symptoms
No adverse events were observed or reported in either group

The finding that meaningful symptom differences appeared as early as day 2 is clinically significant: most cold treatments show effects only by day 4–5, suggesting andrographolide's rapid NF-κB inhibition produces earlier symptom relief than standard symptom management.

Cáceres et al. 1997 — Prevention Trial

This pilot double-blind, placebo-controlled trial [4] examined whether andrographis could prevent colds, rather than merely treat them.

Design:

Setting: rural school in Chile during winter season
n=107 students randomized to Kan Jang (n=54) or placebo (n=53)
Duration: 3 months of daily supplementation
Outcome: incidence of common cold episodes

Results:

Cold incidence in the andrographis group: 30% (16/54 students caught a cold)
Cold incidence in the placebo group: 62% (33/53 students caught a cold)
Relative risk reduction: approximately 51%; absolute risk reduction: 32 percentage points
The andrographis group had a 2.1-fold greater prevention rate than placebo

While this was a pilot study with limitations (small sample, single-site, self-reported illness), the magnitude of effect is notable. The results are consistent with the herb's known effects on NK cell activity and interferon production — immune-priming effects that would logically reduce susceptibility before exposure, not just after infection begins.

Pharmacological Evidence: Dai et al. 2019

The Dai et al. 2019 review in Critical Reviews in Food Science and Nutrition [5] provides the most comprehensive mechanistic summary of andrographolide's pharmacology.

Anti-inflammatory mechanisms confirmed in experimental models:

NF-κB pathway: andrographolide covalently modifies Cys-62 on the p50 subunit, blocking NF-κB nuclear translocation and downstream cytokine gene expression
COX-2 inhibition: andrographolide downregulates cyclooxygenase-2 expression, reducing prostaglandin synthesis — parallel to the mechanism of ibuprofen but through a different molecular target
Nrf2 activation: andrographolide activates the Nrf2 antioxidant pathway, increasing endogenous antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase)
MAPK pathway modulation: inhibits p38 and JNK MAPK signaling, further reducing pro-inflammatory cytokine production

These overlapping, multi-target mechanisms explain the herb's broad anti-inflammatory effects and suggest why it performs well clinically across diverse acute infection types.

Evidence Strength Summary

The evidence base for andrographis is among the stronger profiles for any single medicinal herb, particularly for acute upper respiratory tract infection treatment. For symptom relief in active colds: high confidence based on multiple RCTs and two systematic reviews consistently showing superiority to placebo. For prevention: moderate confidence from a pilot trial showing a clinically meaningful effect. For safety: strong reassurance from numerous trials — adverse events are rare, mild, and not significantly different from placebo.

The primary limitation is that most trials used specific commercial preparations (SHA-10, Kan Jang) at specific doses; evidence is less clear for other andrographis products not standardized to andrographolide content. Overall confidence: high for standardized andrographolide extracts in treating acute upper respiratory infections; moderate for prevention.

References

Andrographis paniculata in the symptomatic treatment of uncomplicated upper respiratory tract infection: systematic review of randomized controlled trialsPoolsup N, Suthisisang C, Prathanturarug S, Asawamekin A, Chanchareon U. Journal of Clinical Pharmacy and Therapeutics, 2004. PubMed 14748896 →
Andrographis paniculata (Chuān Xīn Lián) for symptomatic relief of acute respiratory tract infections in adults and children: A systematic review and meta-analysisHu XY, Wu RH, Logue M, Blondel C, Lai LYW, Stuart B, et al.. PLOS ONE, 2017. PubMed 28783743 →
Use of visual analogue scale measurements (VAS) to assess the effectiveness of standardized Andrographis paniculata extract SHA-10 in reducing the symptoms of common cold: a randomized double blind-placebo studyCáceres DD, Hancke JL, Burgos RA, Sandberg F, Wikman GK. Phytomedicine, 1999. PubMed 10589439 →
Prevention of common colds with Andrographis paniculata dried extract: a pilot double blind trialCáceres DD, Hancke JL, Burgos RA, Wikman GK. Phytomedicine, 1997. PubMed 23195395 →
Overview of pharmacological activities of Andrographis paniculata and its major compound andrographolideDai Y, Chen SR, Chai L, Zhao J, Wang Y, Wang Y. Critical Reviews in Food Science and Nutrition, 2019. PubMed 30040451 →