How does this medication work? What will it do for me?

Fexofenadine belongs to the class of medications called second generation antihistamines, specifically the class known as histamine receptor antagonists. It works by blocking the action of one of the body's natural chemicals known as histamine. Histamine is responsible for many of the symptoms caused by allergies.

Fexofenadine is used for the relief of symptoms associated with seasonal and year-round allergies including sneezing, itchy palate, runny nose, and itchy, tearing, and redness of the eyes. It is also used to relieve the symptoms associated with an allergic skin reaction (chronic idiopathic urticaria) including hives and itchy skin. This medication usually starts to work within one hour.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Allegra® 12 Hour 60 mg tablet
Each peach, oval double convex tablet, engraved on one side with an "e" and with "06" on the other side, contains 60 mg of fexofenadine. Nonmedicinal ingredients: croscarmellose sodium, hydroxypropyl methylcellulose, iron oxide, magnesium stearate, microcrystalline cellulose, polyethylene glycol, povidone, silicon dioxide, starch, and titanium dioxide. These tablets do not contain lactose.

Allegra® 24 Hour 120 mg tablet
Each peach, oblong double convex tablet, plain on one side and engraved on the other side with "012", contains 120 mg of fexofenadine. Nonmedicinal ingredients: croscarmellose sodium, hydroxypropyl methylcellulose, iron oxide, magnesium stearate, microcrystalline cellulose, polyethylene glycol, povidone, silicon dioxide, starch, and titanium dioxide. These tablets do not contain lactose.

How should I use this medication?

For the treatment of seasonal allergies, year-round allergies, or allergic skin reactions, the recommended dose of fexofenadine for adults and children 12 years of age and older is 60 mg every 12 hours or 120 mg once daily. For people with kidney disease, the usual starting dose is 60 mg taken by mouth once daily.

Fexofenadine may be taken with or without food. Avoid prolonged use of this medication, unless recommended by a doctor.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue on with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you are:

  • allergic to fexofenadine or any ingredients of the medication.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • diarrhea
  • dizziness
  • dry eyes
  • headache
  • nausea
  • nosebleed
  • sleepiness
  • stomach upset
  • trouble sleeping

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • fast, pounding, or irregular heartbeat
  • flushing

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • symptoms of a severe allergic reaction, e.g.:
    • chest tightness
    • shortness of breath
    • swelling of the mouth or throat

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take this medication.

Drowsiness: Fexofenadine usually causes minimal drowsiness when used as directed by your doctor or pharmacist. Studies have shown that fexofenadine does not cause drowsiness under normal circumstances. People taking higher-than-recommended doses of fexofenadine may experience drowsiness. Do not drive or operate machinery if you become drowsy while taking this medication.

Reduced kidney function: If you have reduced kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: Fexofenadine passes into breast milk. This medication should not be used by breast-feeding women.

Children: The safety and effectiveness of using this medication have not been established for children younger than 12 years of age.

What other drugs could interact with this medication?

There may be an interaction between fexofenadine and any of the following:

  • antacids that contain aluminum or magnesium

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.