Is Loratadine Safe with Quercetin?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Avoid combining high-dose quercetin (>500mg/day) with loratadine without physician guidance. Monitor for unusual drowsiness or dizziness.
Why this interaction occurs
Quercetin inhibits CYP3A4 and P-glycoprotein enzymes, which are responsible for loratadine metabolism. This can increase loratadine plasma levels, potentially enhancing its antihistamine effects and sedation risk beyond expected non-drowsy profile.
Evidence
Evidence level: moderate.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 1,497 reports mentioning Quercetin. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Quercetin + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Loratadine interactions → · All Quercetin interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.