Asthma is a long-term inflammation of the airways that makes them narrow, swell and overreact to triggers. Fisetin has been tested in the standard mouse model of allergic asthma by several separate research groups, and the results point the same way: fewer inflammatory cells in the lungs, lower levels of the immune signals that drive allergic asthma, and airways that react less [1][2][3].
All of that work is in mice and in cells. There is no published trial of fisetin in people with asthma. This page goes through what the studies measured, where the results are stronger or weaker than they first sound, and what that means if you have asthma and are wondering about a supplement.
Key Takeaways
- In ovalbumin-sensitised mice, fisetin reduced eosinophils, Th2 cytokines and airway hyperresponsiveness in at least four separate studies [1][2][3][4].
- A 2024 mouse study found less airway remodelling: less collagen and thinner airway smooth muscle [5].
- Fisetin relaxed pre-contracted mouse and human airway muscle in a dish, but the living-animal inhaled test in that study used a different flavonol, galangin [6].
- No human trial has tested fisetin for asthma.
Important: This article describes animal and laboratory research and is not medical advice. Asthma attacks can be fatal. Do not reduce or stop an inhaler, a steroid or any other asthma medicine in favour of a supplement. Fisetin can affect enzymes that clear many drugs, so speak to a doctor or pharmacist before adding it.
How the asthma studies are built
Almost every fisetin asthma study uses the same model. Mice are sensitised to ovalbumin, an egg white protein, and then made to breathe it in, which sets off an allergic reaction in the airways. The result looks like allergic asthma: eosinophils (a type of white blood cell) flood the lungs, the airways fill with mucus, and they tighten more than normal when exposed to methacholine, a drug used to test how twitchy airways are.
Researchers then wash out the lungs and count the cells in that fluid, measure cytokines (the immune signalling proteins), stain lung tissue, and measure airway resistance. Those are reasonable outcomes for a mouse, but they are not the outcomes a person with asthma cares about most: fewer attacks, fewer symptoms, better breathing tests, and less need for rescue inhalers. None of those has been measured with fisetin.
Fewer eosinophils and less Th2 signalling
The first study, published in 2011, found that fisetin reduced lung inflammation, goblet cell hyperplasia (overgrowth of mucus-making cells) and airway hyperresponsiveness, and lowered eosinophils and lymphocytes in lung fluid [1]. It also lowered the Th2 cytokines IL-4, IL-5 and IL-13, which drive allergic asthma, along with eotaxin-1 and TSLP, two signals that start the allergic response in the airway lining.
A 2012 study by a different group found the same pattern and added that the effect was dose-dependent: higher doses of fisetin gave larger drops in total cells, eosinophils and IL-4, IL-5 and IL-13 in lung fluid [2]. It also reduced mucus production and the mucus gene Muc5ac, lowered lung tissue expression of IL-17 and IL-33, and reduced airway hyperresponsiveness to methacholine.
A 2018 study gave asthmatic mice 40 or 50 mg/kg of fisetin and found lower eosinophil, neutrophil, monocyte and total white cell counts in lung fluid, lower inflammatory cytokines in blood and lung fluid, and less airway hyperresponsiveness [3]. A 2022 study again found less airway hyperresponsiveness and fewer eosinophils, plus lower COX-2 and less oxidative damage in the lungs [4].
Agreement between four groups using the same model is worth something. It also means the evidence shares one weakness: it all comes from a single kind of short-term allergic mouse model.
The NF-kappaB thread
Three of these studies point to NF-kappaB, a master switch for inflammatory genes. In asthmatic mouse lungs, fisetin blocked the movement of NF-kappaB into the cell nucleus, where it turns those genes on [2], and it reduced NF-kappaB activation in lung tissue and in stimulated bronchial epithelial cells [1]. The 2018 study traced the effect one step further up, to MyD88, a protein that passes danger signals to NF-kappaB [3].
Human lung cells grown in a dish show the same thing. In A549 lung epithelial cells stimulated with IL-1beta, fisetin at 3 to 30 micromolar lowered COX-2, prostaglandin E2, IL-6, IL-8 and TNF-alpha, cut the adhesion molecule ICAM-1 that lets immune cells stick to the airway lining, and raised expression of the antioxidant regulator Nrf2 [7]. In human bronchial epithelial cells, fisetin reduced inflammatory cytokines and chemokines after TNF-alpha stimulation [4]. Our page on fisetin and inflammation covers NF-kappaB in more detail.
Concentrations matter here. 30 micromolar is about 8,587 ng/mL. The peak blood level after a single 1,000 mg dose of plain fisetin was 9.97 ng/mL, and 238.2 ng/mL from a formulated product [8], so the top concentration in those cell studies is roughly 36 times the formulated peak. Levels in airway tissue have not been measured.
Airway remodelling and muscle relaxation
Long-standing asthma can thicken and stiffen the airway wall, a change called remodelling that inhalers do not fully reverse. A 2024 study looked at this directly [5]. In ovalbumin-challenged mice given fisetin by injection into the abdomen, there were fewer inflammatory cells, lower Th2 cytokines, less collagen build-up and thinner airway smooth muscle. In airway smooth muscle cells, fisetin lowered the proteins osteopontin, collagen-I and alpha-smooth muscle actin and slowed cell migration, and the authors link this to the PI3K/AKT pathway.
A 2016 study asked whether fisetin could relax airway muscle the way a reliever inhaler does [6]. Fisetin and a related flavonol, galangin, relaxed mouse tracheal rings and strips of human airway smooth muscle that had been contracted with acetylcholine in the lab. Both inhibited the enzymes PDE4 and PLC-beta. The test in living mice, where the compound was inhaled and lung resistance measured, was done with galangin only. So for fisetin this is evidence from tissue in a dish, not from breathing animals.
Weaker signals worth knowing about
Two other lines of work are often quoted and are thinner than they sound. A 2007 review ranked 45 flavonoids by how strongly they blocked IL-4 production by immune cells, and fisetin was among the four strongest, with an IC50 of 2 to 5 micromolar [9]. That is a test-tube ranking. In blood terms, 2 to 5 micromolar is about 572 to 1,431 ng/mL, which is still above the formulated peak level above.
A 2026 computer study docked 16 compounds against ST2, the receptor for the asthma signal IL-33, and fisetin scored well [10]. But the authors chose hesperetin, not fisetin, as the candidate for further study, and docking is a prediction, not a measurement.
For fisetin and the allergic reaction itself, including histamine and mast cells, see our page on fisetin, allergies and mast cells. For lung scarring and other lung conditions, see fisetin and lung health.
What this means if you have asthma
The mouse results are consistent, and they describe a plausible way fisetin could dampen allergic airway inflammation. They do not show that a fisetin capsule improves asthma in people. Mouse doses do not translate directly to capsules, the doses and routes vary between studies (and several abstracts do not state the route), and plain fisetin is poorly absorbed; our page on fisetin bioavailability goes through the numbers.
Asthma has treatments with outcome data in people, and a controller inhaler that is taken properly remains the thing most likely to prevent a serious attack. If you want to try fisetin anyway, treat it as an addition you discuss with your doctor, not a substitute, and read fisetin drug interactions and fisetin side effects first.
Common questions
Does fisetin help asthma?
In mice with allergic asthma, fisetin reduced airway inflammation, eosinophils and airway hyperresponsiveness [1][2]. It has not been tested in people with asthma.
Can fisetin replace an asthma inhaler?
No. Fisetin has no human data in asthma, and stopping a controller or reliever inhaler can lead to a dangerous attack.
Does fisetin open the airways?
Fisetin relaxed contracted mouse and human airway muscle in the lab [6]. The test in living mice in that study used a related compound, galangin, not fisetin.
How might fisetin work in asthma?
The studies point to lower Th2 cytokines such as IL-4, IL-5 and IL-13 and to blocking NF-kappaB, a switch for inflammatory genes [1][2].
Does fisetin reverse airway remodelling?
In one 2024 mouse study it reduced collagen build-up and airway muscle thickening [5]. That has not been studied in people.
References
- Immunosuppressive effects of fisetin in ovalbumin-induced asthma through inhibition of NF-kappaB activity. J Agric Food Chem (2011). PMID 21899296
- Fisetin, a bioactive flavonol, attenuates allergic airway inflammation through negative regulation of NF-kappaB. Eur J Pharmacol (2012). PMID 22290391
- Fisetin-treatment alleviates airway inflammation through inhibition of MyD88/NF-kappaB signaling pathway. Int J Mol Med (2018). PMID 29568921
- Fisetin Suppresses the Inflammatory Response and Oxidative Stress in Bronchial Epithelial Cells. Nutrients (2022). PMID 35565807
- Fisetin reduces ovalbumin-triggered airway remodeling by preventing phenotypic switching of airway smooth muscle cells. Respir Res (2024). PMID 39402516
- Attenuation of airway smooth muscle contractility via flavonol-mediated inhibition of phospholipase-Cbeta. Am J Physiol Lung Cell Mol Physiol (2016). PMID 26773068
- Fisetin inhibits the generation of inflammatory mediators in interleukin-1beta-induced human lung epithelial cells by suppressing the NF-kappaB and ERK1/2 pathways. Int Immunopharmacol (2018). PMID 29758489
- Enhanced bioavailability and pharmacokinetics of a novel hybrid-hydrogel formulation of fisetin orally administered in healthy individuals: a randomised double-blinded comparative crossover study. J Nutr Sci (2022). PMID 36304817
- Flavonoids and related compounds as anti-allergic substances. Allergol Int (2007). PMID 17384531
- Computational identification of candidate ST2-binding bioactive compounds as putative modulators for severe type 2-high asthma. Comput Biol Chem (2026). PMID 42753515
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. Content is for informational purposes only and is not medical advice; consult a qualified healthcare provider before starting any supplement. As an Amazon Associate we earn from qualifying purchases.