A second-generation antihistamine that is the active carboxylate metabolite of terfenadine. Provides effective relief of allergic rhinitis symptoms and chronic idiopathic urticaria with virtually no sedation or cognitive impairment at recommended doses, considered the least sedating of the second-generation antihistamines. Does not cause QT prolongation (unlike its parent compound terfenadine). Available over-the-counter.
Known hypersensitivity to fexofenadine or terfenadine1,2
Severe renal impairment (dose reduction recommended)
The bottom line
Evidence rating strong. Most-documented uses: treats seasonal and perennial allergic rhinitis, treats chronic idiopathic urticaria, truly non-sedating at recommended doses. 11 sources indexed (2000–2024), with 3 interaction records on file.
The science
How it works, mechanistically.
Core mechanism
Selectively antagonizes peripheral H1 histamine receptors with high binding affinity and very slow receptor dissociation. Inhibits histamine-induced vasodilation, increased vascular permeability, pruritus, and smooth muscle contraction. Does not cross the blood-brain barrier at therapeutic doses (substrate of P-glycoprotein efflux pump and organic anion transporting polypeptide [OATP]). No significant anticholinergic, anti-alpha-adrenergic, or anti-serotonergic activity. Does not affect cardiac potassium channels (no QTc effect).
Class
Second-Generation Antihistamine
Dosing
Dosing & protocol.
Common range
Adults and children >=12 years: 60 mg BID or 180 mg once daily; children 2-11 years: 30 mg BID (as prescribed by your physician)
Recommended form
Oral tablets, orally disintegrating tablets, or oral suspension
Bioavailability approximately 33%. Do NOT take with fruit juices (apple, orange, grapefruit), they inhibit OATP1A2 organic anion transporting polypeptide, reducing absorption by up to 36%. Take with water. Food has no clinically significant effect on absorption. Avoid high-fat meals which may slightly reduce absorption.
Safety
Full safety detail.
Side effects
Headache
Drowsiness (near placebo rates)
Nausea
Dysmenorrhea
Back pain
Upper respiratory symptoms
Contraindications
Known hypersensitivity to fexofenadine or terfenadine1,2
Severe renal impairment (dose reduction recommended)
Concomitant use with aluminum/magnesium-containing antacids (separate by 2 hours)
High-dose quercetin can raise fexofenadine exposure. In a controlled volunteer study, quercetin 500 mg three times daily for 7 days increased fexofenadine AUC by 55% and peak concentration by 68%. Fexofenadine has a wide safety margin, but higher levels may increase headache, dizziness, or drowsiness in sensitive users.
Recommendation: Use caution with high-dose quercetin if you also take fexofenadine daily. Keep the quercetin dose consistent and watch for new drowsiness, dizziness, headache, or palpitations after starting it. If side effects appear, stop the quercetin or use a lower-risk allergy plan with your clinician.
Green tea extract can sharply reduce fexofenadine absorption when taken together. In a randomized crossover study, an EGCG-rich green tea extract reduced fexofenadine AUC and peak concentration by about 70%. This may make fexofenadine less effective for allergic rhinitis or hives.
Recommendation: Take fexofenadine with water, not green tea extract or concentrated catechin products. Separate green tea extract from fexofenadine by at least 4 hours, and be consistent if you use both. If allergy control worsens after starting green tea extract, stop the extract or switch timing and reassess symptoms.
St. John's Wort can change fexofenadine exposure through transporter effects. A single St. John's Wort dose increased fexofenadine peak concentration by 45%, while high-hyperforin repeated use has been associated with lower fexofenadine exposure from peripheral P-glycoprotein induction. The direction can depend on dose, hyperforin content, and duration of use, making allergy control and side effects less predictable.
Recommendation: Avoid starting St. John's Wort casually while taking fexofenadine every day. If you use both, keep the St. John's Wort product and dose stable, monitor allergy control and drowsiness, and tell your prescriber or pharmacist because St. John's Wort has broader drug-interaction risks. Stop St. John's Wort and reassess if fexofenadine seems suddenly weaker or more side-effect prone.
Gómez RM, Moreno P, Compalati E et al.. Update meta-analysis on the efficacy and safety issues of fexofenadine. The World Allergy Organization journal. 2023
Carnovale C, Battini V, Gringeri M et al.. Safety of fexofenadine and other second-generation oral antihistamines before and after the removal of the prescription requirement in Italy and other European countries: A real-world evidence study and systematic review. The World Allergy Organization journal. 2022
Huang CZ, Jiang ZH, Wang J et al.. Antihistamine effects and safety of fexofenadine: a systematic review and Meta-analysis of randomized controlled trials. BMC pharmacology & toxicology. 2019
Singhal A, Agrawal P, Chatterji P et al.. Correction to: Comparison of the Efficacy and Safety of Bilastine 20 mg versus Fexofenadine 180 mg for Treatment of Perennial Allergic Rhinitis: Randomized Controlled Study. Indian journal of otolaryngology and head and neck surgery : official publication of the Association of Otolaryngologists of India. 2024
Meltzer EO, Rosario NA, Van Bever H et al.. Fexofenadine: review of safety, efficacy and unmet needs in children with allergic rhinitis. Allergy, asthma, and clinical immunology : official journal of the Canadian Society of Allergy and Clinical Immunology. 2021
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