Fexofenadine
Fexofenadine hydrochloride
Brand names:Allegra, Allegra Allergy
A second-generation H1 antihistamine with the cleanest cognitive and sedation profile of the operational non-sedating antihistamines. Fexofenadine is FAA-approved for aircrew use, which makes it the preferred antihistamine for aviation operational personnel. The active metabolite of terfenadine (which was withdrawn for QT prolongation), but fexofenadine itself has no cardiac liability at therapeutic doses.
Pharmacology and Actions
Fexofenadine is a selective second-generation peripheral H1 antihistamine with minimal blood-brain barrier penetration. No significant central H1 activity, minimal anticholinergic activity, no cardiac sodium channel blockade (unlike its parent compound terfenadine). Not metabolized significantly - excreted largely unchanged in feces and urine, which is why CYP450 drug interactions are minimal.
Indications
- Seasonal and perennial allergic rhinitis
- Chronic idiopathic urticaria
- Allergic conjunctivitis
- Operational antihistamine of choice when minimal cognitive impact is required (aviation, special operations)
Absolute Contraindications
- Known hypersensitivity to fexofenadine
Precautions and Side Effects
Common (very low frequency): headache, drowsiness (rare), nausea. The cleanest cognitive and operational profile of the operational antihistamines. Cardiac: no QT prolongation at recommended doses, unlike its predecessor terfenadine. Drug interactions: minimal CYP450 interactions; fruit juices (grapefruit, orange, apple) significantly reduce absorption (about 30 percent) via OATP transport inhibition - take with water; antacids containing aluminum or magnesium reduce absorption. Half-life 11 to 15 hours. Pregnancy Category C (limited human data; other second-generation antihistamines have more pregnancy data). Compatible with lactation. Pediatric use approved from 2 years. Renal impairment: reduce dose by 50 percent if CrCl under 80. Hepatic impairment: standard dosing.
Adult Dosing
Pediatric Dosing
Children 2 to 11 years: 30 mg PO twice daily. Children 12 years and older: adult dosing.
Pharmacokinetics
Peak Effect: 2 to 3 hours.
Duration: 12 to 24 hours.
Storage and Handling
Store at room temperature (20 to 25 degrees C). Protect from light and moisture. Stable in standard aid bag and IFAK conditions.
Reconstitution:
Oral formulation only. No reconstitution required.
TCCC and TECC Role
Fexofenadine is not in the TCCC core formulary. It appears in tactical EMS supplemental formularies and is the preferred antihistamine in military aviation medicine due to its FAA approval for aircrew use. Mission impact is none at standard doses. Operational role is chronic management of allergic rhinitis, urticaria, or seasonal complaints in personnel who must maintain peak cognitive performance, particularly aviation crews and special operations operators.
Fexofenadine is the cleanest operational antihistamine. FAA approval for aircrew use means it can be taken by pilots without flight status implications - a meaningful operational advantage over loratadine and cetirizine, both of which carry FAA restrictions in some operational contexts. The trade-off is twice-daily dosing for the standard 60 mg formulation; the 180 mg once-daily formulation provides 24-hour coverage. The fruit juice interaction is significant and underappreciated - taking fexofenadine with orange juice (a common operational practice) reduces absorption by about 30 percent. Take with water.
Taking fexofenadine with fruit juice. Grapefruit, orange, and apple juice all reduce absorption substantially through OATP transporter inhibition. The interaction is large enough (about 30 percent reduction) to compromise clinical effect. Counsel patients explicitly: take with water, separated from juice by at least 4 hours. The other mistake is using fexofenadine in acute anaphylaxis - second-generation antihistamines have no role in anaphylaxis management; epinephrine and diphenhydramine remain the doctrine.
This drug profile is provided as educational reference material for trained medical providers. It is not medical advice, not a substitute for formal training, and not a substitute for current published guidelines or medical direction.
Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances are subject to additional handling, accountability, and documentation requirements per DEA and state law. Always verify dosing, indications, contraindications, and route of administration against current published guidelines and your local protocols before administration.
If this content is being viewed during a medical emergency, call 911 immediately and follow the direction of your local emergency dispatch and medical control. Do not use this reference as a substitute for emergency medical services.
Drug information evolves. Last reviewed dates and source citations are provided for each entry. Confirm currency against the cited source before clinical use.
Penn Tactical Solutions publishes this reference for educational purposes. PTS does not provide medical direction and does not assume responsibility for clinical decisions made in the field. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Educational reference for trained medical providers. Not medical advice. Not a substitute for formal training, current published guidelines, or medical direction. Drug administration is governed by your scope of practice, agency standing orders, medical director protocols, and applicable state and federal regulations. Controlled substances require additional storage, accountability, and documentation per DEA and state law.
In a medical emergency, call 911. This reference is not a substitute for emergency medical services.
Verify dosing, indications, and contraindications against current published guidelines and your local protocols before administration. Confirm content currency against the source citation. Penn Tactical Solutions does not provide medical direction. Clinical responsibility rests with the administering provider, their medical director, and their agency.
Fexofenadine
| IV/IO | None (None) |
| IM | None (None) |
| IN | None (None) |
| PO | 60 mg PO twice daily or 180 mg PO once daily. Take with water (not fruit juice). (60 minutes) |