Allegra (Allegra)
Allergy Relief Treatment
Fexofenadine (Allegra) is a non-drowsy antihistamine used to treat seasonal allergy symptoms and chronic hives. It provides effective relief from sneezing, runny nose, itchy eyes, and skin itching.
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Allegra Product Information
Fexofenadine, commonly known by the brand name Allegra, is a second-generation antihistamine used to alleviate symptoms associated with seasonal allergic rhinitis (hay fever) and chronic idiopathic urticaria (hives). It effectively reduces symptoms such as sneezing, runny nose, itchy eyes, and itchy throat or nose.
This medication works by selectively blocking histamine H1 receptors, preventing histamine from binding and causing allergic reactions. Unlike older antihistamines, fexofenadine does not readily cross the blood-brain barrier, resulting in minimal to no sedative effects, making it a non-drowsy option for allergy relief.
Fexofenadine works by selectively blocking histamine H1 receptors in the body. Histamine is a natural substance released during an allergic reaction, causing symptoms like sneezing, itching, and runny nose. By blocking these receptors, fexofenadine prevents histamine from binding and triggering these allergic responses, thereby relieving symptoms.
Take this medication by mouth with a full glass of water. It can be taken with or without food. Follow the directions on the prescription label and take it at regular intervals. Do not take it more often than directed. It may take several days for symptoms to fully improve.
Allegra usually starts to work within about 1 hour, with peak effect on allergy symptoms around 2–3 hours after a dose.
The effects of Allegra can last for up to 24 hours, depending on the specific formulation and dosage taken.
Allegra Quick View
| Active Ingredient | Fexofenadine |
|---|---|
| Manufacturer | Sanofi (previously Sanofi-aventis, with Chattem, Inc. as its U.S. consumer healthcare division). Perrigo also manufactures store-brand versions. |
| Type | Antihistamine |
| Onset | Approximately 1 hour. |
| Duration | Up to 24 hours depending on the formulation and dose. |
| Food Interaction | Avoid taking fexofenadine with fruit juices (grapefruit, apple, or orange juice) and antacids containing magnesium or aluminum, as these can significantly reduce the absorption and effectiveness of the drug. |
| Alcohol | Fexofenadine generally has minimal direct interactions with alcohol compared to older antihistamines. However, combining fexofenadine with alcohol may increase the risk of drowsiness or dizziness. It is advisable to exercise caution or consult a healthcare professional. |
| Prescription | Over-the-counter (OTC) |
Allegra Side Effects
Common Side Effects
- Cough
- Drowsiness
- Dry mouth
- Headache
- Upset stomach
Uncommon Side Effects
Rare Side Effects
- Allergic reactions (skin rash, itching, hives)
- Angioedema (swelling of the face, eyes, lips, tongue, arms, or legs)
- Trouble swallowing or breathing
Important Warning: Report any signs of allergic reactions or angioedema immediately to your healthcare provider. While generally well-tolerated, some individuals may experience drowsiness, especially when combined with alcohol or other sedating medications.
More Information About Allegra
Storage
Store at room temperature between 20 and 25 degrees C (68 and 77 degrees F). Protect from moisture. Keep out of reach of children and pets. Dispose of any unused medication after the expiration date.
Contraindications
Hypersensitivity to fexofenadine or any of its components. Caution is advised for individuals with kidney disease, and for pregnant or breastfeeding individuals. Co-administration with fruit juice may decrease efficacy.
Drug Interactions
Significant interactions include antacids (especially those containing magnesium or aluminum), erythromycin, and ketoconazole, which can increase fexofenadine levels. Fruit juices (grapefruit, apple, orange) can decrease fexofenadine absorption, reducing its effectiveness.
Allegra FAQs
Allegra typically starts to work within about 1 hour, with its peak effect on allergy symptoms occurring around 2–3 hours after a dose.
While fexofenadine has minimal direct interactions with alcohol, combining them may increase the risk of drowsiness or dizziness. It is generally recommended to exercise caution or consult a healthcare professional.
You should avoid taking Allegra with fruit juices (grapefruit, apple, orange) and antacids containing magnesium or aluminum, as these can reduce the drug's effectiveness.
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Content last updated: 14 Apr 2026
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