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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Brand Name
Quercetin Phenolic
Generic Name
Quercetin,
Active Ingredient
QuercetinCategory
Vitamin C [EPC]
Variants
1
Different strengths and dosage forms
| Strength | Form | Route | NDC |
|---|---|---|---|
| 6 [hp_X]/mL | LIQUID | ORAL | 44911-0013 |
Detailed information about Quercetin Phenolic
References used for this content
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Quercetin Phenolic, you must consult a qualified healthcare professional.
Quercetin is a bioactive flavonoid and polyphenol found in various plants, classified under Vitamin C [EPC] and other therapeutic categories. It is widely utilized for its antioxidant and potential anti-inflammatory properties in clinical and supplemental settings.
The appropriate dosage of Quercetin can vary significantly based on the condition being addressed and the specific formulation used. In clinical studies, common adult dosages range from 500 mg to 1,000 mg per day, often divided into two doses. For general antioxidant support, lower doses of 250 mg may be sufficient. However, for conditions like chronic prostatitis or significant inflammatory stress, healthcare providers may recommend up to 1,000 mg daily. It is critical to note that high-dose Quercetin (exceeding 1,000 mg daily) should only be taken under strict medical supervision due to potential risks to kidney function.
The safety and efficacy of Quercetin in children have not been extensively established. Therefore, it is generally not recommended for pediatric use unless specifically directed by a pediatrician. Most clinical trials have focused on adult populations. If a healthcare provider determines that Quercetin is necessary for a child (for example, as part of an allergenic extract therapy), the dose will be strictly calculated based on the child's weight and age. Parents should never administer Quercetin supplements to children without professional medical guidance.
Patients with pre-existing kidney disease or impaired renal function must exercise extreme caution. Because Quercetin metabolites are primarily excreted through the kidneys, there is a risk of accumulation and potential nephrotoxicity (kidney damage). In many cases, Quercetin is contraindicated (should not be used) in patients with severe renal impairment.
Quercetin undergoes extensive metabolism in the liver. While there are no standardized dose adjustments for hepatic impairment, patients with liver disease should be monitored closely for changes in liver function tests. A lower starting dose may be prudent to avoid taxing the metabolic capacity of the liver.
Geriatric patients often have a natural decline in kidney and liver function. Therefore, healthcare providers typically recommend starting at the lower end of the dosing spectrum (e.g., 250 mg daily) and gradually increasing the dose only if well-tolerated. Monitoring for potential interactions with other medications (polypharmacy) is essential in this population.
To maximize the benefits and minimize the risks of Quercetin, patients should follow these specific instructions:
If you miss a dose of Quercetin, take it as soon as you remember. However, if it is almost time for your next scheduled dose, skip the missed dose and resume your regular schedule. Do not double the dose to catch up, as this increases the risk of gastrointestinal upset and other side effects.
Signs of an acute Quercetin overdose may include severe headache, nausea, vomiting, and abdominal pain. There have been rare reports of kidney damage associated with very high intravenous doses. In the event of a suspected overdose, contact your local poison control center or seek emergency medical attention immediately. Treatment is generally supportive, focusing on maintaining hydration and monitoring renal function.
> Important: Follow your healthcare provider's dosing instructions. Do not adjust your dose or stop taking Quercetin without medical guidance, especially if you are using it as part of a complex treatment regimen for allergies or inflammatory conditions.
While Quercetin is generally well-tolerated when taken at recommended dosages, some individuals may experience mild side effects. The most common issues reported include:
As the dosage increases, the likelihood of experiencing more distinct side effects may also increase:
Rarely, more significant reactions can occur, necessitating a review of the treatment plan:
> Warning: Stop taking Quercetin and call your doctor immediately if you experience any of the following symptoms. These may indicate a severe adverse reaction or toxicity.
The long-term safety of high-dose Quercetin supplementation (beyond 12 weeks) has not been comprehensively studied in large-scale human trials. There is a theoretical concern that chronic high-level inhibition of certain enzymes could interfere with the body's natural detoxification processes or hormonal balance. Some researchers have raised concerns about the potential for Quercetin to act as a pro-oxidant (promoting rather than preventing oxidative stress) at extremely high concentrations over long periods.
As of 2026, there are no FDA black box warnings for Quercetin when used as a dietary supplement or as an ingredient in allergenic extracts. However, this does not mean the substance is without risk. Patients should always adhere to recommended dosages and consult with healthcare professionals, especially if they have underlying health conditions.
Report any unusual symptoms to your healthcare provider. Monitoring your body's response to any new supplement is a key part of maintaining your health and safety.
Quercetin is a potent bioactive compound that can influence multiple physiological systems. It is not a simple vitamin and should be treated with the same respect as a pharmaceutical agent. Patients should be aware that Quercetin's classification as a Corticosteroid [EPC] and Estrogen Receptor Agonist [MoA] means it can potentially interfere with hormonal therapies and the body's natural endocrine balance. Always ensure that your healthcare provider has a complete list of all supplements and medications you are taking to prevent dangerous interactions.
No FDA black box warnings for Quercetin have been issued. Unlike high-risk pharmaceutical drugs, Quercetin is generally categorized as GRAS (Generally Recognized As Safe) for use in food and supplements. However, clinical-grade Quercetin used in allergenic extracts must be administered under the supervision of an allergist or immunologist who is prepared to manage potential systemic reactions.
If you are taking Quercetin long-term or at high doses (above 500 mg daily), your healthcare provider may recommend periodic monitoring:
Quercetin generally does not cause sedation or cognitive impairment. However, if you experience dizziness or headaches as a side effect, you should avoid driving or operating heavy machinery until you know how the supplement affects you.
There is no known direct contraindication between Quercetin and moderate alcohol consumption. However, both alcohol and Quercetin are processed by the liver. Excessive alcohol intake can increase the risk of gastrointestinal irritation and may exacerbate potential liver or kidney stress associated with high-dose Quercetin use.
There is no evidence of a withdrawal syndrome associated with Quercetin. However, if you are using it to manage chronic inflammatory or allergic symptoms, stopping the supplement abruptly may result in a return of those symptoms. It is always best to discuss a tapering plan or alternative therapies with your doctor.
> Important: Discuss all your medical conditions with your healthcare provider before starting Quercetin. Your medical history is the most important factor in determining the safety of any new therapeutic intervention.
While Quercetin is a natural compound, it can have severe interactions with certain drugs.
Quercetin's antioxidant properties may interfere with certain laboratory tests that rely on redox reactions. For example, it might cause false readings in certain urine glucose tests or occult blood tests. Always inform the lab technician if you are taking high doses of Quercetin.
For each major interaction, the mechanism typically involves CYP inhibition (slowing drug breakdown) or P-glycoprotein modulation (changing how drugs are pumped in/out of cells). The clinical consequence is often an increased risk of toxicity from the interacting drug. The management strategy usually involves dose monitoring or separating the timing of the doses.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. A complete medication reconciliation is the only way to ensure your safety.
Conditions where Quercetin must NEVER be used include:
Conditions requiring a careful risk-benefit analysis by a physician include:
Patients who are allergic to certain plants may show cross-sensitivity to Quercetin. This is particularly relevant for those with allergies to:
> Important: Your healthcare provider will evaluate your complete medical history, including any history of kidney stones or hormonal imbalances, before prescribing or recommending Quercetin. Never start a new supplement if you fall into an absolute contraindication category.
Quercetin is currently classified as a compound where safety in pregnancy has not been established. There is no formal FDA pregnancy category assigned to Quercetin as a supplement, but in clinical research, it is handled with extreme caution. Some animal studies suggest that high doses of flavonoids could potentially cross the placenta and affect fetal development or interfere with the action of topoisomerase II (an enzyme involved in DNA replication). Because Quercetin can act as an Estrogen Receptor Agonist [MoA], there is a theoretical risk of interfering with the delicate hormonal balance required to maintain a healthy pregnancy. It is generally advised that pregnant women avoid Quercetin supplements unless specifically prescribed by a high-risk obstetrician.
It is known that flavonoids like Quercetin can pass into breast milk. However, the exact concentration and the subsequent effect on the nursing infant are not well-documented. Given the lack of safety data, the potential for the infant to experience gastrointestinal distress or allergic sensitization exists. Breastfeeding mothers should consult their healthcare provider; in most cases, it is recommended to discontinue Quercetin while nursing to prioritize infant safety.
As previously noted, Quercetin is not approved for general use in children. The metabolic pathways for polyphenols in infants and young children are not fully developed, which could lead to unexpected accumulation. Furthermore, the long-term impact of Quercetin on growth and hormonal maturation has not been studied. Use in children is strictly limited to specialized clinical settings, such as the administration of Standardized Food Allergenic Extract [EPC] by an allergy specialist.
Elderly patients are at a higher risk for adverse effects from Quercetin due to the natural decline in GFR (Glomerular Filtration Rate). Additionally, the elderly are more likely to be taking multiple medications (polypharmacy), significantly increasing the risk of drug-drug interactions. Clinical guidelines suggest that for patients over 65, the total daily intake of Quercetin from supplements should be kept low, and kidney function should be monitored every 3-6 months.
For patients with mild to moderate renal impairment (Stage 2 or 3 CKD), Quercetin dosages must be significantly reduced. For example, a patient with a GFR of 45 mL/min might be limited to 250 mg every other day. Quercetin is generally avoided in Stage 4 and 5 CKD. Dialysis does not efficiently clear Quercetin due to its high protein binding, meaning it can quickly reach toxic levels in dialysis patients.
In patients with liver cirrhosis (Child-Pugh Class B or C), the metabolism of Quercetin is slowed. This can lead to a longer half-life and increased systemic exposure. While no specific dosage guidelines exist, healthcare providers often recommend avoiding high-dose Quercetin in patients with significant hepatic dysfunction to prevent potential hepatotoxicity.
> Important: Special populations require individualized medical assessment. What is safe for one person may be dangerous for another based on age, organ function, and pregnancy status.
Quercetin's molecular mechanism is exceptionally broad. It primarily functions as a competitive inhibitor of various enzymes. It binds to the ATP-binding site of signaling kinases, such as Phosphoinositide 3-kinase (PI3K), which plays a role in cell growth and immune response. As an Ammonium Ion Binding Activity [MoA] agent, it may help modulate nitrogenous waste products at the cellular level. Its role as a Corticosteroid Hormone Receptor Agonist [MoA] involves binding to glucocorticoid receptors, which explains its ability to mimic some of the anti-inflammatory effects of steroids without the same systemic side effects. Furthermore, as an Estrogen Receptor Agonist [MoA], it can bind to ER-beta receptors, influencing various estrogen-dependent tissues.
The dose-response relationship of Quercetin is non-linear; higher doses do not always result in greater antioxidant activity and may, in some cases, induce pro-oxidant effects. The time to onset for its anti-inflammatory effects (such as mast cell stabilization) is typically 20-60 minutes after absorption. The duration of effect is approximately 6-12 hours, which is why twice-daily dosing is often recommended. Tolerance development is not commonly observed with Quercetin, but its efficacy can be enhanced by the presence of other antioxidants like Vitamin C.
| Parameter | Value |
|---|---|
| Bioavailability | <10% (Aglycone form) |
| Protein Binding | >98% (Primarily Albumin) |
| Half-life | 11 - 28 hours |
| Tmax | 1.5 - 3.0 hours |
| Metabolism | Hepatic (Glucuronidation/Sulfation) |
| Excretion | Renal (approx. 70%), Fecal (approx. 30%) |
Quercetin is classified within the Vitamin C [EPC] therapeutic area as a bioflavonoid. It is also a key component in various Allergenic Extract [EPC] categories. Related medications include other flavonoids like Rutin, Hesperidin, and Dihydroquercetin (Taxifolin). Within the EPC system, it is also uniquely linked to Tetracycline-class Antimicrobials [EPC] and Adrenocorticotropic Hormones [EPC] due to its diverse biological targets.
Common questions about Quercetin Phenolic
Quercetin is a versatile flavonoid used primarily for its antioxidant and anti-inflammatory properties. Healthcare providers often suggest it to help manage symptoms of seasonal allergies, such as sneezing and itching, because it helps stabilize mast cells that release histamine. It is also used to support cardiovascular health by promoting healthy blood pressure and protecting the lining of blood vessels from oxidative damage. Some clinical studies have explored its use in reducing inflammation in chronic conditions like prostatitis. Additionally, it is a common ingredient in immune-support supplements, often paired with Vitamin C and Zinc. Always consult your doctor to see if Quercetin is appropriate for your specific health needs.
Most people tolerate Quercetin well, but the most common side effects include mild stomach upset, nausea, or abdominal cramps, especially when taken without food. Some individuals may also experience a mild headache shortly after taking a dose. At higher doses, typically above 1,000 mg per day, some people report a tingling sensation in their arms or legs. These side effects are usually temporary and resolve as the body becomes accustomed to the supplement or if the dosage is reduced. If you experience severe symptoms like persistent vomiting or signs of kidney distress, you should stop use and contact your healthcare provider immediately. Always start with a lower dose to assess your personal tolerance.
There is no direct evidence that moderate alcohol consumption is dangerous when taking Quercetin. However, because both alcohol and Quercetin are processed by the liver, heavy drinking could potentially increase the metabolic burden on this organ. Alcohol can also irritate the stomach lining, which may worsen the gastrointestinal side effects sometimes seen with Quercetin. Furthermore, alcohol can affect blood pressure and hydration, potentially complicating the cardiovascular effects of the supplement. It is generally best to limit alcohol intake when starting any new therapeutic regimen. If you have a history of liver or kidney disease, you should discuss alcohol use with your doctor before taking Quercetin.
The safety of Quercetin during pregnancy has not been established through rigorous clinical trials in humans. Because Quercetin has mild hormonal activity and can act as a weak estrogen receptor agonist, there is a theoretical risk that it could interfere with the hormonal changes necessary for a healthy pregnancy. Some animal studies have raised concerns about high-dose flavonoids affecting fetal development. Most medical professionals recommend avoiding Quercetin supplements during pregnancy and breastfeeding out of an abundance of caution. If you are pregnant or planning to become pregnant, you should rely on dietary sources of Quercetin, like apples and onions, rather than high-dose supplements. Always consult your obstetrician before taking any new supplement.
The time it takes for Quercetin to work depends on the condition being treated. For acute allergic reactions, some people may notice a slight reduction in symptoms within 20 to 60 minutes as the compound begins to stabilize mast cells. However, for chronic inflammatory conditions or cardiovascular support, it may take 4 to 8 weeks of consistent daily use to see significant clinical benefits. Quercetin's effects are often cumulative, meaning they build up over time as the compound modulates cellular signaling pathways. It is important to maintain a consistent dosing schedule to achieve the best results. If you do not see any improvement after two months, you should consult your healthcare provider to re-evaluate your treatment plan.
Yes, you can generally stop taking Quercetin suddenly without experiencing withdrawal symptoms, as it is not a habit-forming substance. However, if you were using Quercetin to manage chronic symptoms like hay fever or joint inflammation, those symptoms may return shortly after you stop. To avoid a flare-up of symptoms, some people choose to gradually reduce their dose over a week or two. It is always a good idea to inform your healthcare provider before stopping any supplement that is part of your long-term health strategy. They can help you determine if another treatment is needed to replace the benefits you were receiving from Quercetin. Stopping suddenly is usually only necessary if you experience a severe allergic reaction or other serious side effect.
If you miss a dose of Quercetin, you should take it as soon as you remember. If it is already very close to the time for your next scheduled dose, it is better to skip the missed dose and simply take your next one at the regular time. You should never take two doses at once to make up for a missed one, as this can increase the risk of stomach upset or headache. Maintaining a consistent level of Quercetin in your system is helpful for its anti-inflammatory effects, but a single missed dose is unlikely to significantly impact your long-term results. To help you remember, try taking your supplement at the same time each day, such as with breakfast or dinner. If you frequently miss doses, consider using a pill organizer or a reminder app.
There is currently no clinical evidence to suggest that Quercetin causes weight gain. In fact, some preliminary research in animal models has suggested that Quercetin might help support a healthy metabolism and reduce the formation of new fat cells, though these effects have not been proven in humans. Because Quercetin can help reduce inflammation, it might actually assist in weight management efforts for some individuals by improving overall metabolic health. Any sudden or unexplained weight gain while taking Quercetin should be reported to your doctor, as it could be a sign of fluid retention related to kidney or heart issues, rather than the supplement itself. Overall, Quercetin is considered weight-neutral for the vast majority of patients. Always pair supplements with a balanced diet and exercise.
Quercetin can interact with several types of medications, so caution is necessary. It may increase the risk of bleeding if taken with blood thinners like warfarin or aspirin, and it can interfere with how your body processes certain antibiotics, particularly fluoroquinolones. Additionally, because Quercetin inhibits certain liver enzymes (like CYP3A4), it can cause other drugs—such as some blood pressure medications or statins—to build up to higher levels in your blood. This can increase the risk of side effects from those medications. It may also lower blood sugar, which could be a concern if you are on diabetes medication. You must provide your healthcare provider with a full list of all your current medications before starting Quercetin to ensure there are no dangerous interactions.
Quercetin is a naturally occurring compound and is not a patented drug, so it is widely available as a generic dietary supplement from many different manufacturers. It is sold under various brand names and as a generic 'Quercetin' product in health food stores and pharmacies. While the chemical structure of Quercetin remains the same, different products may vary in their 'bioavailability'—how well they are absorbed by the body. Some generic versions may include additives like Bromelain or Vitamin C to enhance absorption and efficacy. When choosing a generic Quercetin supplement, look for products that have been third-party tested for purity and potency. While generic versions are generally more affordable, always ensure you are purchasing from a reputable source to guarantee the quality of the ingredient.
Other drugs with the same active ingredient (Quercetin)