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Allegra 12 Hour Allergy

Generic name: fexofenadineFEX-oh-FEN-a-deen ]
Brand names: Allegra 12 Hour Allergy, Allegra 24 Hour Allergy, Allegra Allergy, Allegra OTC, Aller-Ease, ... show all 8 brands
Drug class: Antihistamines

Medically reviewed by on Jan 20, 2023. Written by Cerner Multum.

What is Allegra 12 Hour Allergy?

Allegra 12 Hour Allergy is an antihistamine that is used to treat the symptoms of seasonal allergies (hay fever) in adults and children.

Allegra 12 Hour Allergy is also used to treat skin itching and hives caused by a condition called chronic idiopathic urticaria in adults and children at least 6 years old.

There are many brands and forms of fexofenadine available. Not all brands are listed on this leaflet.

Allegra 12 Hour Allergy may also be used for purposes not listed in this medication guide.

Allegra 12 Hour Allergy side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Allegra 12 Hour Allergy may cause serious side effects. Stop using Allegra 12 Hour Allergy and call your doctor at once if you have:

Common side effects of Allegra 12 Hour Allergy may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Do not take Allegra 12 Hour Allergy with fruit juice (such as apple, orange, or grapefruit).

Before taking this medicine

You should not use Allegra 12 Hour Allergy if you are allergic to it.

Ask a doctor or pharmacist if Allegra 12 Hour Allergy is safe to use if you have:

Ask a doctor before using this medicine if you are pregnant or breastfeeding.

Older adults may be more sensitive to the effects of this medicine. If you are 65 or older, ask a doctor before taking Allegra 12 Hour Allergy.

This medicine may contain phenylalanine and could be harmful if you have phenylketonuria (PKU).

How should I take Allegra 12 Hour Allergy?

Use exactly as directed on the label, or as prescribed by your doctor.

Always follow directions on the medicine label about giving cough or cold medicine to a child.

Take this medicine only with water.

Take the disintegrating tablet on an empty stomach.

Shake the oral suspension (liquid) before you measure a dose. Use the dosing cup provided, or use a medicine dose-measuring device (not a kitchen spoon).

Remove an orally disintegrating tablet from the package only when you are ready to take the medicine. Place the tablet on your tongue and allow it to dissolve, without chewing. Swallow several times as the tablet dissolves.

Call your doctor if your symptoms do not improve, or if they get worse.

Store Allegra 12 Hour Allergy in its original package at room temperature, away from moisture and heat. Do not allow liquid medicine to freeze.

What happens if I miss a dose?

Allegra 12 Hour Allergy is used when needed. If you are on a dosing schedule, skip any missed dose. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include dry mouth, dizziness, or drowsiness.

What should I avoid while taking Allegra 12 Hour Allergy?

Do not take Allegra 12 Hour Allergy with fruit juice (such as apple, orange, or grapefruit). These juices can make it harder for your body to absorb this medicine.

Avoid taking an antacid within 2 hours before or after you take Allegra 12 Hour Allergy. This medicine should not be used at the same time as antacids that contain magnesium or aluminum.

Ask a doctor or pharmacist before using other cough or cold medicines that may contain similar ingredients.

What other drugs will affect Allegra 12 Hour Allergy?

Using Allegra 12 Hour Allergy with other drugs that make you drowsy can worsen this effect. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Ask a doctor or pharmacist before using Allegra 12 Hour Allergy with any other medications, especially:

This list is not complete. Other drugs may affect Allegra 12 Hour Allergy, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Frequently asked questions

Further information

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

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