Health Guide


What is it?

Quercetin is a bioflavonoid that is used for allergic conditions, asthma, hay fever, rheumatoid arthritis, and lupus. It is also used in diabetes and cancer.

Other names for Quercetin include: Bioflavonoid, Meletin, and Sophretin.

Ask your doctor, nurse, or pharmacist if you need more information about this medicine or if any information in this leaflet concerns you.

Before Using:

Tell your doctor if you

  • are taking medicine or are allergic to any medicine (prescription or over-the-counter (OTC) or dietary supplement)
  • are pregnant or plan to become pregnant while using this medicine
  • are breast feeding
  • have any other health problems, such as high blood pressure or heart or blood vessel disease


Talk with your caregiver about how much Quercetin you should take. The amount depends on the strength of the medicine and the reason you are taking Quercetin. If you are using this medicine without instructions from your caregiver, follow the directions on the medicine bottle. Do not take more medicine or take it more often than the directions tell you to.

To store this medicine:

Keep all medicine locked up and away from children. Store medicine away from heat and direct light. Do not store your medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down and not work the way it should work. Throw away medicine that is out of date or that you do not need. Never share your medicine with others.

Drug and Food Interactions:

Do not take Quercetin without talking to your doctor first if you are taking:

  • Cyclosporine (Neoral(R), Sandimmune(R), Sandimmune IV(R), Sangcya(R))
  • Digoxin (Lanoxin(R))
  • Certain medicines used to treat infection (ciprofloxacin (Cipro(R)), gatafloxacin (Tequin(R)), levofloxacin (Levaquin(R)), norfloxacin (Noroxin(R)), ofloxacin (Floxin(R)), sparfloxacin (Zagam(R)), trovafloxacin (Trovan(R)))


  • Before taking Quercetin, tell your doctor if you are pregnant or breast feeding

Side Effects:

Stop taking your medicine right away and talk to your doctor if you have any of the following side effects. Your medicine may be causing these symptoms which may mean you are allergic to it.

  • Breathing problems or tightness in your throat or chest
  • Chest pain
  • Skin hives, rash, or itchy or swollen skin

Other Side Effects:

This medicine may also cause other side effects. Tell your doctor if you have side effects that you think are caused by this medicine.


1. Murray, MT: Encyclopedia of Nutritional Supplements. Prima Publishing, Rocklin, CA; 1996.

2. Jaspan J, Maselli R, Herold K et al: Treatment of severely painful diabetic neuropathy with an aldose reductase inhibitor: Relief of pain and improved somatic and automatic nerve function. Lancet 1983;2:758-762.

3. Varma SE et al: Diabetic cataracts and flavonoids. Science 1977;195:205.

4. Shoskes DA, Zeitlin SI, Shahed A et al: Quercetin in men with category III chronic prostatitis: a preliminary prospective, double-blind, placebo-controlled trial. Urology 1999; 54(6):960-963.

5. Hsiu SL, Hou YC, Wang YH et al: Quercetin significantly decreased cyclosporin oral bioavailability in pigs and rats. Life Sci 2002; 72:227-235.

6. Hilliard JJ, Krause HM, Bernstein JA et al: A comparison of active site binding of 4-quinolones and novel flavone gyrase inhibitors to DNA gyrase. Adv Exp Med Biol 1995; 390:59-69.

7. Wang Y-H, Chao P-D L, Hsiu S-L et al: Lethal quercetin-digoxin interaction in pigs. Life Sci 2004; 74:1191-1197.

Last Updated: 7/4/2018
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