Quercetin is a flavonoid, which is a plant pigment, and has antioxidant properties. The antioxidant acts as an antihistamine and anti-inflammatory, which may lessen the severity of allergy symptoms, such as runny nose, swelling, and hives. Using quercetin for allergies may help eliminate the need of antihistamine drugs in some patients, but its use has not been studied extensively and there is not sufficient evidence that it is a viable treatment option for allergies. Using quercetin for allergies is safe for use in most people, however, and does not typically cause the drowsiness that is common with some antihistamines.
People who suffer from allergies have symptoms that are triggered by allergens, such as dust, pet dander, smoke, or pollen. The allergic reaction often leads to watery eyes, runny nose, sneezing, itching, and hives. Antihistamines help stop the allergic reaction and relieve symptoms, and quercetin may act as a natural antihistamine in some allergy patients. Some people, particularly those who experience undesirable side effects from traditional antihistamines, prefer taking quercetin for allergies because it is a natural substance.
As with many herbs and supplements, side effects from taking quercetin for allergies are usually minimal and mild. Some people have reported headache and stomach upset after taking the drug, but it is generally considered safe and non-problematic. Anecdotal evidence suggests that some people take quercetin regularly to keep allergies under control instead of using it only when they have symptoms. Long-term relief is a possible benefit to using quercetin as opposed to traditional antihistamines that are designed for quick symptom relief.
One of the biggest cons of using quercetin for allergies is that it may not work. Many people do not experience symptom relief when taking a quercetin supplement, and there is no definitive evidence supporting the use of quercetin in allergy sufferers. The flavonoid is also typically hard for the body to absorb, meaning any beneficial effects could be limited.
Monitoring dosage carefully is important. One downside to using supplements for allergy relief is that there are fewer studies with evidence to support a safe and effective dose. Anything less than 1 gram is usually considered safe, but daily doses of 1 gram or more could result in kidney damage. Pregnant and breastfeeding women shouldn’t take quercetin, and a safe dose for children has not been established.
Natural substances still have the potential to interact with other supplements and medications. People who take anticoagulants should not take quercetin, as quercetin can enhance the effect of blood thinners. Medications that affect the liver, corticosteroids, and cyclosporine can also lead to dangerous interactions. Allergy sufferers should always check with their doctors before adding a medication or supplement to their allergy treatment plans.