Fexofenadine: English spelling of Fexofenadin

Fexofenadine is the English spelling of the H1 antihistamine Fexofenadin. In Germany and German-speaking countries, the substance is almost exclusively referred to as Fexofenadin without the final e. In English package inserts, international scientific publications, and on some imported preparations, the form Fexofenadine appears instead. Pharmacologically and chemically, this is the same substance. This page is a note and reference to the detailed active ingredient page for Fexofenadin.

Fexofenadine is a non-sedating second-generation antihistamine. Well-known brand names are Telfast, Allegra, and numerous generics. It is used to treat allergic rhinitis and chronic urticaria and is sold without a prescription in many countries. A complete pharmacological overview of mechanism of action, indications, dosage, side effects, and drug interactions can be found on the Fexofenadin main page.

Mechanism of Action

Fexofenadine competitively blocks the histamine H1 receptor on mucous membranes, smooth muscle, and peripheral nerves. This significantly reduces allergic symptoms such as itching, sneezing, rhinorrhea, conjunctivitis, and hive formation. Unlike first-generation antihistamines, fexofenadine barely crosses the blood-brain barrier because it is a substrate of the P-glycoprotein transporter. This results in a favorable non-sedating profile.

Central effects such as drowsiness, sedation, or cognitive impairment occur very rarely, making fexofenadine the first choice for allergic complaints when patients need to be fully functional during the day. A detailed mechanism description can be found on the Fexofenadin active ingredient page.

Indications

• Allergic rhinitis, seasonal with pollen allergy and year-round with dust mites or animal hair
• Chronic idiopathic urticaria (hives) with hive formation and itching
• Allergic conjunctivitis as adjunctive treatment in hay fever
• Adjuvant for other allergic skin conditions with pronounced itching

Fexofenadine is not first-line for anaphylaxis or acute bronchial obstruction. For these life-threatening reactions, intramuscular adrenaline and, if necessary, glucocorticoids are the treatments of choice. A complete list of indications can be found on the Fexofenadin main page.

Dosage and Administration

Adults and adolescents 12 years and older: 120 mg once daily for allergic rhinitis, 180 mg once daily for chronic urticaria.

Children between 6 and 11 years: 30 mg twice daily, age-appropriate liquid formulation available.

Administration: With water, preferably on an empty stomach, because fatty meals or fruit and vegetable juices such as apple, orange, or grapefruit juice can significantly reduce absorption. At least 1 hour interval from antacids containing aluminium or magnesium.

Renal impairment: With eGFR below 30 ml per minute, 60 mg per day in adults, 30 mg once daily in children. Hepatic impairment: Usually no dose adjustment required.

Duration of therapy: For seasonal allergy during the pollen season, for year-round allergy and chronic urticaria long-term as needed.

Detailed recommendations can be found on the Fexofenadin main page.

Side Effects

Frequent: Headache, drowsiness, nausea, dry mouth. Drowsiness is significantly less common than with first-generation antihistamines.

Occasional: Dizziness, sleep disturbances, skin rash, pruritus.

Rare: Allergic reactions, anaphylaxis, tachycardia, visual disturbances, Stevens Johnson syndrome.

A complete overview of side effects can be found on the Fexofenadin main page.

Drug Interactions

• Antacids containing aluminium or magnesium: Significantly reduce absorption, maintain a minimum interval of 2 hours.
• Fruit and vegetable juices (Apple, orange, grapefruit): Inhibit the OATP transporter and reduce bioavailability. Take with water.
• Erythromycin and ketoconazole: Increase plasma levels, clinical relevance at normal dosing is low.
• Other antihistamines: No combination necessary as they have the same mechanism of action.
• Sedating substances: No relevant additive effect because fexofenadine is barely sedating.

Special Information

Spelling: Fexofenadine with an e at the end is the English form; in German-language sources, Fexofenadin without an e is used. Both refer to the same substance. When writing prescriptions and contacting pharmacies, the spelling customary in the country should be used.

Pregnancy: Data on fexofenadine are limited. In pregnancy, more established H1 antihistamines such as loratadine or cetirizine are preferred, individual consultation recommended. Breastfeeding: Transition into breast milk in small amounts, use possible after consultation.

Children: Approved from 6 years of age in Germany, age-appropriate liquid formulation available.

Elderly patients: Well-suited due to low sedation, adjust dose in case of renal impairment.

Before therapy: Allergy diagnosis with skin test or specific IgE in chronic or unclear complaints, supplemented by allergen avoidance and, if necessary, specific immunotherapy.

Lifestyle for allergies: Allergen avoidance where possible, good sleep hygiene, stress avoidance, regular exercise if appropriate. Antihistamines supplement but do not replace causative measures.

Fitness to drive: Usually not impaired because of minimal sedating effect.

You might also be interested in

• Fexofenadin, the pharmacological base text on the substance
• Cetirizin, another modern antihistamine
• Loratadin, another H1 antihistamine
• Levocetirizin, active enantiomer of cetirizine
• Desloratadin, active metabolite of loratadine

Frequently Asked Questions

Sources

• Gelbe Liste, Fexofenadin active ingredient profile
• BfArM, Federal Institute for Drugs and Medical Devices
• AWMF, Guidelines for allergic rhinitis and chronic urticaria
• German Allergy and Asthma Association