Table 2.

Quercetin drug interaction severity (based on Medscape online database [194]).

Drug classification	Example of drugs	Type of drug interaction	Mechanism
Antibiotics	Ciprofloxacin Fleroxacin Gemifloxacin Levofloxacin Ofloxacin Moxifloxacin	Minor	Quercetin decreases effects of mentioned antibiotics by pharmacodynamic antagonism
Antihistamines	Fexofenadine Loratadine	Minor	Quercetin will decrease the level or effects of these antihistamines by P-glycoprotein (MDR1) efflux transporter
Antidepressants	Amitriptyline Nortriptyline	Monitor Closely	Quercetin will decrease the level or effects of these antidepressants by P-glycoprotein (MDR1) efflux transporter. Also Quercetin can also exert antidepressant effects by inhibiting the hyperactivity of the hypothalamic-pituitary-adrenal axis [195]
Cardiovascular	Atorvastatin Digoxin Lovastatin	Monitor Closely	Quercetin will decrease the level or effects of these cardiovascular drugs by P-glycoprotein (MDR1) efflux transporter
Corticosteroids	Budesonide Cortisone Deflazacort Dexamethasone Fludrocortisone Methylprednisolone Prednisolone	Monitor Closely	Quercetin will decrease the level or effects of Corticosteroids drugs by P-glycoprotein (MDR1) efflux transporter
Antigout Drugs	Colchicine	Monitor Closely	Quercetin will decrease the level or effects of Colchicine by P-glycoprotein (MDR1) efflux transporter
Sex Hormones	Conjugated-Estrogens Estradiol Mestranol	Monitor Closely	Quercetin will decrease the level or effects of these drugs by P-glycoprotein (MDR1) efflux transporter
Immunosuppressants	Ciclosporin Sirolimus Tacrolimus	Monitor Closely	Quercetin will decrease the level or effects of these drugs by P-glycoprotein (MDR1) efflux transporter
Anti-cancer	Imatinib Nilotinib Paclitaxel Vincristine Vinblastine	Monitor Closely	Quercetin can reverse the resistance mechanisms of anticancer drugs through the inhibition of group P function and ABCB1 gene expression in many cell lines. Also it will decrease the level or effects of these drugs by P-glycoprotein (MDR1) efflux transporter
Antivirals	Saquinavir Indinavir Maraviroc Nelfinavir Ritonavir	Monitor Closely	Quercetin will decrease the level or effects of these drugs by P-glycoprotein (MDR1) efflux transporter
Anti-cancer	Topotecan Everolimus	Serious	Topotecan: Quercetin will increase the level or effects of topotecan by P-glycoprotein (MDR1) efflux. So, avoid concomitant use of P-glycoprotein inhibitors. The interaction with IV topotecan may be less severe. Everolimus: Quercetin will decrease the level or effects of Everolimus by P-glycoprotein (MDR1) efflux transporter