Quercetin

Are there any interactions with medications?



Antibiotics (Quinolone antibiotics)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Taking quercetin along with some antibiotics might decrease the effectiveness of some antibiotics. Some scientists think that quercetin might prevent some antibiotics from killing bacteria. But it's too soon to know if this is a big concern.

Quinolone antibiotics include ciprofloxacin (Cipro), levofloxacin (Levaquin), ofloxacin (Floxin), moxifloxacin (Avelox), gatifloxacin (Tequin), and others.



Cyclosporine (Neoral, Sandimmune)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

A small study in healthy volunteers shows that giving quercetin before cyclosporine increases blood levels of the cyclosporine and lengthens the time it remains in the body.



Medications changed by the liver (Cytochrome P450 2C8 (CYP2C8) substrates)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Some medications are changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down some medications. Taking quercetin along with some medications that are broken down by the liver can increase the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.

Some medications that are changed by the liver include paclitaxel (Taxol), rosiglitazone (Avandia), amiodarone (Cordarone), docetaxel (Taxotere), tretinoins, repaglinide (Prandin), verapamil (Calan, Isoptin, Verelan, etc.), and others.



Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Some medications are changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down some medications. Taking quercetin along with some medications that are broken down by the liver can increase the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.

Some medications that are changed by the liver include celecoxib (Celebrex), diclofenac (Voltaren), fluvastatin (Lescol), glipizide (Glucotrol), ibuprofen (Advil, Motrin), irbesartan (Avapro), losartan (Cozaar), phenytoin (Dilantin), piroxicam (Feldene), tamoxifen (Nolvadex), tolbutamide (Tolinase), torsemide (Demadex), and warfarin (Coumadin).



Medications changed by the liver (Cytochrome P450 2D6 (CYP2D6) substrates)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Some medications are changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down some medications. Taking quercetin along with some medications that are broken down by the liver can increase the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.

Some drugs that are changed by the liver include amitriptyline (Elavil), codeine, flecainide (Tambocor), haloperidol (Haldol), imipramine (Tofranil), metoprolol (Lopressor, Toprol XL), ondansetron (Zofran), paroxetine (Paxil), risperidone (Risperdal), tramadol (Ultram), venlafaxine (Effexor), and others.



Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Some medications are changed and broken down by the liver. Quercetin might decrease how quickly the liver breaks down some medications. Taking quercetin along with some medications that are broken down by the liver can increase the effects and side effects of these medications. Before taking quercetin, talk with your healthcare provider if you take any medications that are changed by the liver.

Some drugs that are changed by the liver include calcium channel blockers (diltiazem, nicardipine, verapamil), chemotherapeutic agents (etoposide, paclitaxel, vinblastine, vincristine, vindesine), antifungals (ketoconazole, itraconazole), glucocorticoids, alfentanil (Alfenta), fentanyl (Sublimaze), losartan (Cozaar), fluoxetine (Prozac), midazolam (Versed), omeprazole (Prilosec), lansoprazole (Prevacid), ondansetron (Zofran), propranolol (Inderal), fexofenadine (Allegra), amitriptyline (Elavil), amiodarone (Cordarone), citalopram (Celexa), sertraline (Zoloft), and numerous others.



Medications moved by pumps in cells (P-Glycoprotein substrates)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

Quercetin might affect the way certain medications are processed by the body. Quercetin might make these medications easier for the body to use and make them last longer in the body.

Some of the drugs that may be affected in these ways by quercetin include paclitaxel, diltiazem, cyclosporine, saquinavir, digoxin, cancer drugs (etoposide, vinblastine, vincristine, vindesine), antifungals (ketoconazole, itraconazole), protease inhibitors (amprenavir, indinavir, nelfinavir), H2 antagonists (cimetidine, ranitidine), verapamil, corticosteroids, erythromycin, fexofenadine (Allegra), loperamide (Imodium), quinidine, and others.



Warfarin (Coumadin)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

A small test tube study shows that quercetin might increase the effects that warfarin has on the body. Taking quercetin and warfarin together might increase the chance of side effects of warfarin such as bruising and bleeding.

Dosing considerations for Quercetin.

The following dose has been studied in scientific research:

BY MOUTH:
  • For prostate pain and swelling (prostatitis): 500 mg twice daily.

Therapeutic Research Faculty copyright

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.


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