Allergic rhinitis
Not recommended
Dietary supplements, flavonoids (local classification). Also registered in Russia as an angioprotective agent.
ATC code: A11JA-QUERCETIN (Quercetin – local code)
Brand names
Solgar Quercetin Complex, Quercetin Now Foods, Thorne Quercetin Phytosome
Quercetin is a flavonoid found in onions, apples, capers, citrus, and tea. Cellular models describe antioxidant, anti-inflammatory, and senolytic activity (selective senescent cell clearance when combined with dasatinib). Oral bioavailability of pure quercetin is low. Large RCTs in humans with lifespan or clinical outcome endpoints are unavailable.
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
Quercetin is a plant flavonoid sold as an "anti-allergy" supplement and promoted for allergic rhinitis to ease a runny nose and sneezing. Convincing benefit for this use has not been shown, and there is no solid evidence base behind it. Allergic rhinitis responds to proven options: intranasal corticosteroids and antihistamines, and in some cases allergen-specific immunotherapy. Do not take quercetin instead of this treatment, or you risk missing care with proven benefit.
Not recommended
Quercetin is a plant flavonoid found in onions, apples and capers, marketed in supplements as an anti-aging and longevity aid, sometimes paired with other so-called senolytics. There is no convincing human evidence that it slows aging, rejuvenates skin or extends lifespan. The compound itself is well tolerated at usual supplement doses. For healthy aging, the approaches that hold up are the proven ones: sleep, physical activity, diet, not smoking and sun protection.
Not recommended
Quercetin is a plant flavonoid found in onions, apples and capers, sold as a supplement for immunity and for preventing colds and respiratory infections. For this use there is no convincing benefit: the data come from small, low-quality trials. For an acute respiratory infection, rest, fluids and symptom relief help, and prevention rests on flu vaccination and hand hygiene. The compound itself is safe at typical dietary and supplement amounts.
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Use in pregnancy has not been studied; supplement is not recommended.
Use during breastfeeding has not been studied; supplement is not recommended.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Quercetin is evaluated for the following indications with varying evidence strength: Anti-aging and longevity (evidence tier D), Allergic rhinitis (evidence tier D), Immune support and respiratory infection care (evidence tier D). See the full indication matrix with dosing and citations above on this page.
Common side effects of Quercetin (≥ 1 in 100): GI discomfort, Headache, Extremity tingling (at doses over 1 g/day). See the Safety section for uncommon and serious reactions.
FDA category N. Use in pregnancy has not been studied; supplement is not recommended.
Use during breastfeeding has not been studied; supplement is not recommended.
Quercetin is contraindicated in: Pregnancy and breastfeeding; Age under 12; Severe renal impairment; Hypersensitivity; Concurrent warfarin, ciclosporin, tacrolimus. Full list in the Safety section.