Hay fever season is looming, and many allergy sufferers may be wishing they had a way to prevent the misery of sneezing and sniffling. One reader made a serendipitous discovery: quercetin taken for glaucoma calmed allergy symptoms quickly. What should you know about this supplement?
Quercetin for Glaucoma and Allergies:
Q. You’ve written about NasalCrom for allergies and I ordered it with high hopes. I also have glaucoma and wanted to get off Nasacort although it is working beautifully for my nose. I also take Xyzal or Zyrtec daily. Sad to say, despite using it two or three times a day for three months, NasalCrom did not seem to do anything for my allergies.
I did stumble across a supplement that seems to help–quercetin. It may reduce the risk of glaucoma, specifically benefiting retinal cells (Frontiers in Molecular Neuroscience, Sep. 7, 2017).
Oddly, I found that it helps with allergies too! I would be verging on breakthrough sneezing and found the symptoms settle down within 20 minutes of taking quercetin. You are supposed to take twice a day. Imagine my surprise when I checked the reviews and read that others also reported relief from allergy symptoms.
What Is Quercetin?
A. Thank you so much for alerting us to this approach to managing allergy symptoms. Quercetin is a flavonoid compound that is found in many different plants. Onions, kale and apples are particularly good sources of quercetin in the diet. Capers, berries, Brassica vegetables like broccoli or cabbage, grapes and tomatoes are other foods that contain quercetin (Nutrients, March 15, 2016). Even tea has a small amount.
When we checked the medical literature, we were quite surprised to find research showing that quercetin is more effective than cromolyn (the active ingredient in NasalCrom) in blocking the inflammatory compounds released by mast cells (PLOS One, March 28, 2017). These studies were conducted in tissue cultures, and this compound might not be as effective when it is taken as a dietary supplement. However, research in rats suggests that it may ease allergic rhinitis, aka hay fever (European Archives of Oto-Rhino-Laryngology, Aug. 2017).
We’d love to see a clinical trial in humans, but they are expensive. Quercetin, as a natural compound, cannot be patented and therefore it is unlikely such a study will be conducted. On the other hand, we have heard from another reader who found quercetin very helpful.
Quercetin Eased Postnasal Drip:
Q. I started taking quercetin after reading that it could help with allergy symptoms. The product I took contained vitamin C, magnesium and bromelain in addition to quercetin.
My most bothersome allergy symptom was postnasal drip. It woke me up in the middle of the night.
Taking quercetin stopped the drip and allowed me to sleep better. It didn’t cause any side effects that I noticed.
A. Thanks for your interesting testimonial. Quercetin is a plant-derived flavonoid. It is found in a wide range of foods including onions, apples, berries, tea and citrus fruits. However, most people who want to increase their intake use supplements.
A Japanese randomized controlled trial found that quercetin improved allergy symptoms, including eye itching, sneezing, runny nose and sleep problems, significantly better than placebo (European Review for Medical and Pharmacological Sciences, June 2022).
Fighting Allergies With Quercetin:
Q. I have suffered from seasonal allergies for years. When I moved from New York to Florida, I began to suffer all year long and tried many allergy medicines.
In May 2019, I started to experience daily headaches and very itchy, burning eyes that would not respond to any medication. I saw an ENT who did a CT scan of my sinus which was clear. They examined my optic nerve and it was normal. An MRI of my head with contrast was normal. I also saw two allergists for testing and medications. In the process, I tried many OTC and prescription drugs.
During April 2020, I saw your articles about quercetin. From the first day I took one 500 mg capsule, my headache was gone! My eyes also felt a little better.
I had to switch brands due to the first brand being out of stock. The second brand also relieved the headache and even worked much better on the eyes. Now I take one capsule daily and feel great!
The Potential of a Natural Compound:
A. Thank you for sharing your success with quercetin. This natural compound is found in kale, apples, onions, broccoli, berries, tomatoes, grapes and red wine. It is a flavonoid that has been shown to prevent the release of histamine from mast cells (Molecules, May 2016).
Sadly, there are very few clinical trials of quercetin. Japanese researchers have found that a quercetin derivative, isoquercetin, can counteract itchy eyes due to cedar pollen allergy (International Archives of Allergy and Immunology, March 17, 2009). Despite this dearth of human studies, Iranian scientists have urged their colleagues to consider the potential for quercetin to treat allergic diseases (Allergy, Asthma, and Clinical Immunology, May 14, 2020).