Fexofenadine

Medically Reviewed by Dr. Harshi Dhingra, M.D.

Last Reviewed: Jul 27, 2022

Warnings

Allegra Risks, Warnings, and Complications

Allegra can cause serious symptoms and health problems in certain groups of people. Ask a doctor or pharmacist about other treatment options for allergy symptoms if you are at high risk of complications from Allegra use.

EFFECTS ON FOCUS AND CONCENTRATION: Taking Allegra can cause dizziness and drowsiness, which can affect your ability to concentrate and focus. The risk is higher if you drink alcohol or take other medications that also affect alertness. You should avoid driving a motor vehicle, operating machinery, or doing anything that requires you to be fully alert until you know how Allegra affects you.
PEOPLE WITH PHENYLKETONURIA: Phenylketonuria is a rare, inherited disorder in which an amino acid called phenylalanine builds up in the body. People with phenylketonuria should not take the rapidly dissolving tablets of Allegra because they contain phenylalanine. The regular tablets and oral suspension don't contain phenylalanine and are safer. If you have phenylketonuria, do not self treat with Allegra allergy medicine. Talk to your doctor for medical advice and get your doctor’s approval before taking Allegra.

Precautions Before Starting Allegra

Tell your healthcare professional if you are allergic to Allegra, any of the active or inactive ingredients in Allegra tablets or oral suspension, or any other drugs.

Give your healthcare professional a complete medical history. Allegra may not be right for people with a medical condition such as kidney disease.

Give your healthcare professionals a complete list of medications, including prescription drugs, nonprescription drugs, vitamins, supplements, and herbal products. This can help avoid possible drug interactions.

Tell your doctor if you are pregnant, could be pregnant, are planning a pregnancy or are breastfeeding.

Precautions During Use of Allegra

Keep all your regular medical and laboratory appointments while on Allegra. Your doctor may want to order certain laboratory tests while you are on this medicine.

If you are taking aluminum or magnesium antacids such as Maalox or Mylanta, take them 30-60 minutes away from Allegra.

Tell your doctor if you become pregnant while on Allegra.

Tell all your doctors you are taking Allegra before any surgery, including dental procedures.

Allegra can make you drowsy and dizzy. Do not drive or operate machinery until you know how this medicine affects you.

Avoid drinking alcohol while on Allegra as this can make the side effects worse.

Allegra Drug Interactions

Taking Allegra with certain other drugs can affect how it works. Interactions between Allegra and other medicines can also increase the risk of severe adverse effects. The following medications can have possible drug interactions with Allegra:

Ketoconazole (Nizoral)
Erythromycin (E-Mycin, E.E.S., Erythrocin)

The above list may not describe all possible Allegra interactions. Give your healthcare professional and pharmacist a list of all your current medications, including prescription drugs, nonprescription drugs, dietary supplements, and herbal products. Also, tell your healthcare provider if you smoke, drink alcohol, or use recreational drugs because some of these substances can cause serious health complications when used with prescription medicines.

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