Fexofenadine: 7 things you should know
Medically reviewed by Carmen Fookes, BPharm. Last updated on Dec 28, 2019.
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). 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 at 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.
- 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 to provide relief from itching that occurs as a result of chronic urticaria (hives). Symptoms of hives include raised, red, itchy bumps, streaks, or blotches on the skin.
- May be used in the treatment of allergic conjunctivitis, insect bites, and other allergic skin disorders.
- Fexofenadine, even in dosages exceeding those recommended, is the least sedating of all second-generation antihistamines and is considered the antihistamine of choice for people in safety-critical jobs such as airline pilots.
- Can be taken once a day.
- 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.
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, tiredness, nausea or back pain in some people.
- 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.
- 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.
- May interact with some other medications, including aluminum and magnesium-containing antacids, erythromycin, ketoconazole, and fruit juices (such as apple, grapefruit, and orange).
Notes: 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. For a complete list of all side effects, click here.
- 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.The effects of fexofenadine are still seen 12 hours after an oral dose.
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
- botulinum toxin
- intraconazole or ketoconazole
- grapefruit juice
- opioids, such as hydrocodone
- prokinetic agents such as metoclopramide
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.
Fexofenadine. Revised 10/2019. Drugs.com https://www.drugs.com/ppa/fexofenadine.html
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.
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More about fexofenadine
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Drug Images
- Drug Interactions
- Support Group
- Pricing & Coupons
- 140 Reviews
- Drug class: antihistamines
- Fexofenadine Orally Disintegrating Tablets
- Fexofenadine Tablets
- Fexofenadine Oral Suspension
- Fexofenadine (Advanced Reading)