Pronunciation: uh-l-EH-g-r-uh
Generic name: fexofenadine
Brand names: Allegra, Allegra ODT
Drug class: Antihistamines

Medically reviewed by Sanjai Sinha, MD. Last updated on Aug 26, 2024.

What is Allegra?

Allegra is an antihistamine that reduces the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose.

Allegra is used to treat the symptoms of seasonal allergies (hay fever) in adults and children.

Allegra is also used to treat skin itching and hives caused by a condition called chronic idiopathic urticaria in adults and children.

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

Warnings

Ask a doctor or pharmacist before taking Allegra if you are allergic to any drugs, or if you have kidney disease.

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

There may be other drugs that can affect Allegra. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.

Stop using Allegra and get emergency medical help if you think you have used too much medicine, or if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Tell your doctor if your symptoms do not improve, or if they get worse after you start taking Allegra. Never use more than the recommended dose.

Before taking this medicine

Ask a doctor or pharmacist if it is safe for you to take Allegra if you are allergic to any drugs, or if you have kidney disease.

It is not known whether Allegra will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medicine. It is not known whether fexofenadine passes into breast milk or if it could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby. Allegra tablets and capsules may be used to treat seasonal allergy symptoms in children who are at least 6 years old. Allegra oral suspension (liquid) may be used in children ages 2 through 11. When treating chronic idiopathic urticaria, the liquid may be used in children as young as 2 months old. Do not give this medicine to a child without medical advice.

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

How should I take Allegra?

Use Allegra exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Take the regular tablet with a full glass of water. Do not use any other type of liquid. Shake the oral suspension (liquid) well just before you measure a dose. To be sure you get the correct dose, measure the liquid with a marked measuring spoon or medicine cup, not with a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.

To take fexofenadine orally disintegrating tablets (Allegra ODT):

• Keep the tablet in its blister pack until you are ready to take the medicine. Open the package and peel back the foil from the tablet blister. Do not push a tablet through the foil or you may damage the tablet.

• Using dry hands, remove the tablet and place it in your mouth. It will begin to dissolve right away.

• Do not swallow the tablet whole. Allow it to dissolve in your mouth without chewing.

• Swallow several times as the tablet dissolves. If desired, you may drink liquid to help swallow the dissolved tablet.

Take the Allegra disintegrating tablet on an empty stomach, at least 1 hour before or 2 hours after a meal.

Tell your doctor if your symptoms do not improve, or if they get worse after you start taking Allegra. Never use more than the recommended dose.

Store Allegra at room temperature away from moisture and heat. Keep the medicine bottle tightly closed.

Related/similar drugs

prednisone, fluticasone nasal, hydroxyzine, cetirizine, montelukast, loratadine, diphenhydramine, promethazine, Zyrtec, Xolair

What happens if I miss a dose?

Allegra 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?

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

Avoid taking an antacid within 2 hours before or after you take Allegra Do not use. Allegra 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.

Allegra side effects

Get emergency medical help if you have any of these signs of an allergic reaction to Allegra: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Stop taking Allegra and call your doctor if you have fever, chills, body aches, cough, or other flu symptoms.

Less serious Allegra side effects may include:

• nausea, diarrhea, upset stomach;

• menstrual cramps;

• drowsiness, tired feeling;

• headache; or

• muscle or back pain.

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.

What other drugs will affect Allegra?

Before taking this medication, tell your doctor if you regularly use other medicines that make you sleepy (such as cold or allergy medicine, sedatives, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by Allegra.

Tell your doctor about all other medicines you use, especially:

• ketoconazole (Nizoral); or

• erythromycin (E.E.S., EryPed, Ery-Tab, Erythrocin, Pediazole).

This list is not complete and other drugs may interact with Allegra. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.

Frequently asked questions

• What are the most common skin conditions? (with photos)
• Allegra vs Claritin: Which is more effective for allergies?
• Can I take Allegra in the morning and Zyrtec in the evening?

View more FAQ

Further information

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

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

Medical Disclaimer

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