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Fexofenadine: 7 things you should know

Medically reviewed by Carmen Fookes, BPharm. Last updated on Feb 9, 2021.

1. How it works

  • Fexofenadine is an antihistamine that works selectively on peripheral histamine-1 (H-1) receptors (these are histamine receptors that are located outside of the brain and spinal cord, such as in the gastrointestinal tract, the blood vessels, and the respiratory tract). Because it acts on peripheral histamine receptors, fexofenadine is much less likely to cause drowsiness compared with some older antihistamines.
  • Histamine is a chemical that is released by mast cells in response to an allergen, and it is responsible for many of the symptoms of an allergic reaction, such as swelling of the mucous membranes, sneezing, and itching. Fexofenadine binds to histamine receptors and prevents histamine from having an effect on those receptors, which reduces the symptoms of an allergic reaction.
  • Fexofenadine belongs to the group of drugs known as antihistamines. Fexofenadine may also be called an H1-antihistamine, a second-generation antihistamine, or a nonsedating antihistamine.

2. Upsides

  • May be used for the short-term relief of runny nose, sneezing, itching of the nose or throat, or itchy watery eyes due to hay fever or other respiratory allergens.
  • Used to treat allergic-type reactions due to hay fever (seasonal allergic rhinitis) or other upper respiratory allergies.
  • Effective at controlling symptoms such as sneezing, itching, watery eyes, and runny nose.
  • May be used off-label to provide relief from itching that occurs as a result of chronic idiopathic urticaria (hives). Symptoms of hives include raised, red, itchy bumps, streaks, or blotches on the skin. National guidelines support this use.
  • May be used in the treatment of allergic conjunctivitis, insect bites, and other allergic skin disorders.
  • Fexofenadine, even in dosages exceeding those recommended, does not cross the blood-brain barrier to any appreciable degree, which makes it one of the least sedating of all second-generation antihistamines. Fexofenadine is considered the antihistamine of choice for people in safety-critical jobs such as airline pilots.
  • Can be taken once a day or twice a day. The dosage for adults for once-daily formulations is 180mg once daily (maximum is 180 mg/day) and the dosage for twice-daily formulations is 60mg every 12 hours (maximum 120mg/day). For chronic urticaria, the dosage range has been reported as 20 to 240mg twice daily.
  • Twice daily dosing should be used in children aged less than 12 years. The maximum dose in children is 60 mg/day in those aged 2 to 12 years.
  • May be given daily on a regular basis when allergens are most prevalent (such as during spring or summer).
  • Fexofenadine is approved for use in children older than 6 months with chronic urticaria and those older than two years with seasonal allergic rhinitis.
  • No dosage adjustment is required in liver disease.
  • Available over-the-counter although children aged less than six years with hives will still require a prescription.
  • Generic fexofenadine is available.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • A headache, dizziness, nausea, or back pain in some people. Children aged 6 months to 5 years have a 4% to 12% reported incidence of vomiting after a dose of fexofenadine. Diarrhea, nausea, muscle and other pain, and infections have also been reported.
  • Generally does not cause drowsiness, although this may be more likely at higher dosages in some people.
  • Some evidence suggests that other antihistamines such as cetirizine may be more effective than fexofenadine at relieving symptoms of allergic rhinitis and urticaria; however, results have been inconsistent.
  • The dosage of fexofenadine should be reduced to an initial dose of 60mg in people with kidney disease. The time for fexofenadine to be excreted is 59% longer in those with mild to moderate kidney disease (41 to 80 mL/minute) and 72% longer in those with severe renal impairment (11 to 40 mL/minute). The maximum concentration of fexofenadine is also increased in those with kidney disease.
  • Fexofenadine, like all other antihistamines, may decrease the response to skin prick tests. Discontinue fexofenadine at least 72 hours prior to skin testing.
  • Available as oral tablets, an oral suspension, disintegrating tablets, and gel-coated tablets. Some disintegrating tablets contain phenylalanine.
  • May interact with some other medications, including aluminum and magnesium-containing antacids, erythromycin, ketoconazole, and fruit juices (such as apple, grapefruit, and orange).
  • Not considered a preferred antihistamine for use during pregnancy. Cetirizine, loratadine, and levocetirizine are in pregnancy category B whereas fexofenadine and desloratadine are in pregnancy category C. Sedating antihistamines, such as chlorpheniramine, hydroxyzine, and dexchlorpheniramine are considered the safest antihistamines to be used during pregnancy.
  • Do not use fexofenadine if you have had an allergic reaction to it in the past.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Fexofenadine treats allergic-type reactions such as hay fever and urticaria and evidence suggests it is the least sedating of all the antihistamines available.

5. Tips

  • Oral fexofenadine tablets may be taken with or without food. Disintegrating fexofenadine tablets (such as Allegra ODT) should be taken on an empty stomach - one hour before or two hours after food.
  • Shake fexofenadine suspension well before measuring the dose using a marked measuring spoon or cup.
  • Do not take fexofenadine with fruit juices such as apple, orange, or grapefruit, as this may affect absorption. Take only with water.
  • During the pollen season, your doctor may advise you to take fexofenadine every day if you suffer from seasonal allergic rhinitis.
  • Generally does not cause drowsiness; however, rarely some patients may be affected so caution should be exercised before driving or operating machinery. Alcohol and other sedative-like drugs may cause additional reductions in alertness if used with fexofenadine.
  • Seek urgent medical advice if you have hives and develop swelling of the face, throat, or tongue, dizziness, drooling, difficulty speaking, or shortness of breath.
  • Fexofenadine is not a substitute for epinephrine which is used for the treatment of severe allergies and anaphylaxis.
  • Fexofenadine is available as a suspension or disintegrating tablets for adults and children who have difficulty swallowing tablets.
  • See your doctor if your mild allergy symptoms have not improved after three days of treatment with fexofenadine, or if your hives persist for more than six weeks despite taking fexofenadine.
  • Do not take fexofenadine during pregnancy or while breastfeeding unless on the advice of your doctor.

6. Response and effectiveness

  • Fexofenadine is the major active metabolite of terfenadine (another antihistamine).
  • Some symptom relief may occur within 10-20 minutes of the first dose. Within an hour, all patients should notice a reduction in their allergy symptoms with peak effects seen by two to three hours. On average, it takes about two hours for fexofenadine to have an effect. The time to peak may be delayed to four hours with a high-fat meal.
  • The effects of fexofenadine last for at least 24 hours after an oral dose.

7. Interactions

Medicines that interact with fexofenadine may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with fexofenadine. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with fexofenadine include:

  • antacids containing aluminum or magnesium
  • anticholinesterase inhibitors
  • anticholinergics such as benztropine
  • azelastine
  • betahistine
  • botulinum toxin
  • buprenorphine
  • chlormethiazole
  • intraconazole or ketoconazole
  • erythromycin
  • grapefruit juice
  • minocycline
  • opioids, such as hydrocodone
  • prokinetic agents such as metoclopramide
  • rifampin.

Note that this list is not all-inclusive and includes only common medications that may interact with fexofenadine. You should refer to the prescribing information for fexofenadine for a complete list of interactions.

References

  • Fexofenadine. Revised 07/2020. Drugs.com https://www.drugs.com/ppa/fexofenadine.html
  • Kar S, Krishnan A, Preetha K, Mohankar A. A review of antihistamines used during pregnancy. J Pharmacol Pharmacother. 2012;3(2):105-108. doi:10.4103/0976-500X.95503

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use fexofenadine only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2021 Drugs.com. Revision date: February 9, 2021.