Allegra (Fexofenadine) - Oral

What Is Allegra?

Allegra containing fexofenadine is a second-generation antihistamine drug used to treat the symptoms of seasonal allergies (hay fever), also known as seasonal allergic rhinitis, in adults and children 2 years and older. It can also treat chronic hives (idiopathic urticaria) in children 6 months and older.

Allegra is a non-drowsy antihistamine with a low side-effect profile, meaning most people tolerate it well. Antihistamines work by blocking the histamine (H1) receptors to reduce allergy symptoms. Histamine is a chemical released by the immune system in the body in response to an allergic reaction. When the immune system identifies an allergen, it releases histamine, creating those common allergy symptoms like a stuffy nose and itchy eyes.

Allegra is available over-the-counter (OTC) without a prescription in tablet and liquid suspension formulations. It is also available as an orally disintegrating tablet (ODT) under the brand name Allegra ODT.

Drug Facts

Generic Name: Fexofenadine

Brand Name(s): Allegra, Allegra ODT

Drug Availability: Over-the-counter (OTC)

Administration Route: Oral

Therapeutic Classification: Antihistamine

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Fexofenadine hydrochloride

Dosage Form(s): Tablet, orally disintegrating tablet, suspension (liquid)

What Is Allegra Used For?

Allegra relieves symptoms of seasonal allergic rhinitis, commonly known as hay fever in adults and children 2 years and older.

Symptoms of hay fever can include:

  • Runny or stuffy (congested) nose
  • Sneezing
  • Red, itchy, or watery eyes
  • Itchy nose or throat

Allegra also helps relieve chronic idiopathic urticaria symptoms such as hives and red or itchy raised areas of the skin.

An illustration with drug information about Allegra (Fexofenadine)

Verywell / Zoe Hansen

How to Take Allegra

If you are using Allegra to self-treat allergy symptoms, read all directions carefully on the product's packaging. Consult your pharmacist or healthcare provider if you have trouble understanding when or how to take it.

The usual dose for Allegra is once a day or twice daily (every 12 hours), depending on the dosage strength, taken by mouth with or without food.

For the suspension (liquid) form, shake the bottle well before use and measure each dose carefully using a special measuring device or spoon. If taking the tablets, you can drink water with your dose but do not take fruit juices (such as apple, grapefruit, or orange). These juices can decrease the absorption of the medication, making it less effective.

You should also avoid taking antacids containing aluminum and magnesium with Allegra. If you take antacids, take them at least four hours apart from your Allegra dose. Antacids can also decrease the absorption of this medication.

Contact your healthcare provider if your condition does not improve or if it worsens.


Store this medicine in a well-closed container at room temperature (between 68 F and 77 F). Keep it away from direct light, heat, and moisture. Do not store it in the bathroom. Keep all the medication locked out of the sight and reach of children and pets.

How Long Does Allegra Take to Work?

On average, it takes two hours for fexofenadine to have a peak effect. Most people should notice a decrease in their allergy symptoms within two to three hours. The effects of fexofenadine last for nearly 24 hours after an oral dose.

What Are the Side Effects of Allegra?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at or 800-FDA-1088.

Common Side Effects

Allegra may cause some side effects. Contact your healthcare provider if the symptoms do not go away or become severe.

The most common side effects in people aged 12 and older include:

  • Headache
  • Back pain
  • Dizziness
  • Pain in the extremity
  • Stomach pain

Commonly reported side effects in children 6 to 11 years old are:

Common side effects in children 6 months to 5 years are:

  • Diarrhea
  • Sleepiness and fatigue
  • Vomiting
  • Runny nose

Severe Side Effects

Some side effects can be severe. Contact the healthcare provider right away if you notice symptoms of an allergic reaction, such as:

  • Hives
  • Itching
  • Rashes
  • Swelling of the face, throat, tongue, lips with difficulty breathing or swallowing

Report Side Effects

Allegra may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Allegra Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For symptoms of hay fever:
    • For oral dosage form (capsules, tablets):
      • Adults and children 12 years of age and older—60 milligrams (mg) two times a day, or 180 mg once a day.
      • Children 6 to 11 years of age—30 mg two times a day.
      • Children 4 to 6 years of age—Use and dose must be determined by your doctor .
      • Children and infants up to 4 years of age—Use is not recommended .
    • For oral dosage form (disintegrating tablets):
      • Children 6 to 11 years of age—30 milligrams (mg) two times a day, on an empty stomach.
      • Children 4 to 6 years of age—Use and dose must be determined by your doctor .
      • Children and infants up to 4 years of age—Use is not recommended .
    • For oral dosage form (suspension):
      • Children 4 to 11 years of age—30 milligrams (mg) or 5 milliliters (mL) two times a day.
      • Children younger than 4 years of age—Use and dose must be determined by your doctor .
  • For symptoms of chronic hives:
    • For oral dosage form (capsules, tablets):
      • Adults and children 12 years of age and older—60 milligrams (mg) two times a day, or 180 mg once a day.
      • Children 4 to 11 years of age—30 mg two times a day.
      • Children younger than 4 years of age—Use and dose must be determined by your doctor .
    • For oral dosage form (disintegrating tablets):
      • Children 4 to 11 years of age—30 milligrams (mg) two times a day, on an empty stomach.
      • Children younger than 4 years of age—Use and dose must be determined by your doctor .
    • For oral dosage form (suspension):
      • Children 4 to 11 years of age—30 milligrams (mg) or 5 milliliters (mL) two times a day.
      • Children 6 months to 4 years of age—15 mg or 2.5 mL two times a day.
      • Children younger than 6 months of age—Use and dose must be determined by your doctor .


Fexofenadine is known to be eliminated from the body through the kidneys. Because of this, people with decreased kidney function are at increased risk of toxic effects with Allegra.

If you are 65 or older, or have kidney problems, consult a healthcare provider about what dose you should take with Allegra.

Missed Dose

If you forget to take a dose of Allegra, take it as soon as you remember it. However, if it is nearly the time for the next dose, skip the missed dose and take the following doses regularly. Never take two doses at one time to make up for a missed one.

Overdose: What Happens If I Take Too Much Allegra?

Symptoms of an Allegra overdose may include:

  • Dizziness
  • Drowsiness
  • Dry mouth

In studies, no clinically significant reactions occurred with doses of Allegra up to 11 times the recommended dose. Always adhere to the dosing instructions on the product label and consult your healthcare provider.

What Happens If I Overdose on Allegra?

If you think you or someone else may have overdosed on Allegra, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Allegra, call 911 immediately.


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It is important that your doctor check your progress at regular visits to allow for changes in your dose and to help reduce any side effects .

What Are Reasons I Shouldn’t Take Allegra?

Do not use Allegra if you are allergic to fexofenadine or any other ingredients in the tablet or suspension. Hypersensitivity reactions may include angioedema (swelling under the skin), chest tightness, difficulty breathing, flushing, and anaphylaxis.

Moreover, inform your healthcare provider if you have kidney disease. You may need to adjust how much of the medication you take.

Consult your healthcare provider if you are pregnant, plan to become pregnant, or are breastfeeding.

What Other Medications Interact With Allegra?

Allegra is relatively a well-tolerated drug, but it can interact with a few medicines. Consult your healthcare provider or pharmacist about your prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products.

Allegra can interact with:

  • Ketoconazole and Ery-Tab (erythromycin): These medications can increase the plasma concentration of fexofenadine. You may need to change your dose and monitor for side effects more carefully.
  • Antacids containing aluminum or magnesium: Take these a few hours before or after taking Allegra to prevent interactions.
  • Fruit juices, such as orange, grapefruit, or apple juice: Drinking these while taking Allegra can reduce the bioavailability (how it is absorbed in the body) of the drug.

What Medications Are Similar?

Apart from Allegra, there are other OTC second-generation antihistamines available without a prescription, such as:

  • Zyrtec (cetirizine): Zyrtec is long-lasting and starts working within one hour, but it is a sedative (which means it may make you drowsy). It also treats hives.
  • Claritin (loratadine): Claritin can take a few hours to start working and is minimally sedative. It treats hay fever and hives.

Fexofenadine is significantly more effective than loratadine in relieving eye symptoms and nasal congestion. Furthermore, It is also considerably better than loratadine in improving quality of life. There are no significant side effects, and the combined incidence of drowsiness is less than with cetirizine and loratadine.

Xyzal (levocetirizine) is also an antihistamine used to treat the symptoms of seasonal and year-round allergies. However, it is a prescription medicine, meaning you'll need to visit a prescribing healthcare provider to receive a prescription for it.

Frequently Asked Questions

  • What is Allegra used for?

    Allegra (fexofenadine) is an antihistamine drug used to relieve allergy symptoms of seasonal allergic rhinitis, commonly known as hay fever. Hay fever symptoms can include sneezing, an itchy nose or throat, and watery, red eyes. It also treats urticaria symptoms such as hives, itching, and skin redness.

  • How does Allegra work?

    Allegra is an antihistamine that blocks histamine's effects. Histamine is a chemical in the body that causes allergy symptoms.

  • What drugs should not be taken with Allegra?

    Allegra can interact with drugs such as ketoconazole, erythromycin, and antacids. Ask your healthcare provider about dose adjustment if you take these drugs while using Allegra.

  • What are the side effects of Allegra?

    Some common side effects of this medication are headache, dizziness, diarrhea, and flu-like symptoms.

  • When do I stop taking Allegra?

    Read the instructions on the packet carefully. Unless otherwise told by a healthcare provider, you can generally stop taking the medicine if you notice an improvement in your allergies and no longer need it to relieve symptoms.

How Can I Stay Healthy While Taking Allegra?

Allegra is a well-tolerated antihistamine that works better for people than many other medications of the same class. It is a non-sedative antihistamine that won't make you too tired, even at high doses. Once you take it, you should feel symptom relief within an hour.

Allergic rhinitis can be irritating and interfere with your day-to-day life. In addition to treating symptoms with Allegra, you can also:

  • Avoid triggers, such as by keeping the windows closed when pollen counts are high.
  • Use a saline nasal spray to clear allergens from your nose.
  • Ask your healthcare provider about prescription options or allergy shots, which may be used in more severe cases.

If your symptoms are unmanageable with Allegra, talk to your healthcare provider about other options to get your allergies under control.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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