Does Quercetin interact with Fexofenadine hydrochloride?

Medication · antihistamine

Supplements and Fexofenadine hydrochloride.

Every documented pair, every citation. Below: 1 documented pair grouped by mechanism.

Fexofenadine hydrochloride, sold under the brand names Telfast, Allevia, Allegra, is an antihistamine.

Fexofenadine hydrochloride is an antihistamine. The class divides into two generations. Older agents (chlorphenamine, promethazine, diphenhydramine) cross the blood brain barrier and cause sedation. Newer agents (cetirizine, loratadine, fexofenadine) mostly do not. UK community prescribing is mostly the newer agents for allergic rhinitis and urticaria. The supplement surface for them is small, because they have low CYP involvement and minimal additive sedation effect. The older agents stack with anything else sedating (alcohol, benzodiazepines, valerian, kava, magnesium glycinate at higher doses) and with anticholinergic supplements. The latter matters in older patients, given the cognitive decline signal in data on sustained anticholinergic burden. Fexofenadine specifically is a P-glycoprotein substrate and shows reduced absorption with fibre supplements at high intake, and with fruit juices. The BNF flag is real, but the clinical magnitude is small at standard doses.

Below are the 1 documented pair we have explicitly assessed against Fexofenadine hydrochloride in the Distil database: 1 amber. The pairs cluster around 1 mechanism: P-glycoprotein inhibition (raises drug levels). Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.

Documented interactions

Last reviewed 14 June 2026. Each interaction below is assessed against PubMed-indexed evidence.

P-glycoprotein inhibition (raises drug levels)

Amber Does Quercetin interact with ?

Quercetin can raise blood levels of fexofenadine by blocking a transporter pump (P-glycoprotein). Fexofenadine is a low-risk antihistamine, so this rarely causes problems, but if you take both regularly and notice more drowsiness or side effects, separating them or lowering the quercetin dose is reasonable.

Evidence: Supported by human study data.

PMID 19221726 · BNF: Fexofenadine

What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.

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