Allegra Allergy Medication Information

Allegra is an over-the-counter allergy medication used to treat seasonal allergy symptoms. In 2011, Allegra moved from prescription-only availability to over-the-counter purchase. In addition, it is now available in generic form.

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active ingredient

Fexofenadine is the active ingredient in the brand drug Allegra. Many store brands and other companies are now able to offer generic fexofenadine.

Dosage Information

Several forms of Allegra are available.

Allegra 24hr is a 180 mg tablet taken once a day.

Allegra 12 Hour is a 60mg tablet taken twice a day.

Allegra D contains both fexofenadine and pseudoephedrine (a decongestant). Allegra D fights both sneezing/runny nose and congestion. The “D” stands for decongestant, which will help relieve sinus congestion.

(It’s important to note that decongestants shouldn’t be taken long-term, so if you choose to take Allegra-D, don’t take it more than a few days before switching to a medication that doesn’t contain a decongestant.)

There are several formulations of Allegra for children that are available over the counter. The dosage varies depending on the type of Allegra. Refer to the box to determine the exact dose of medicine needed for your child’s age.

Allegra should not be taken together with fruit juices.

Allegra should be taken on an empty stomach with a full glass of water. Taking it with fruit juice may make it less effective.

Side effects

Side effects of Allegra are rare and may include headache, vomiting/nausea and/or stomach pain and drowsiness.

If you have certain conditions, there may be risks associated with taking Allegra. Talk to your healthcare provider before taking it if you:

  • are pregnant or breastfeeding
  • Have kidney disease
  • Are over the age of 65

How it works

Allegra is an antihistamine that stops the effects of histamine in the body. Histamine is what causes allergy symptoms when a person is exposed to an allergen. Unlike some other antihistamines, Allegra does not usually cause drowsiness. Some serious side effects should not be ignored. If you experience any of the following problems, contact your health care provider immediately.

Who shouldn’t take it

Some people should not take Allegra. Do not take it if you are allergic to any ingredient in Allegra.

What do you want to know

Like all antihistamines, Allegra will work better for some people than others. If you suffer from seasonal allergy symptoms, you may want to talk to your healthcare provider about trying Allegra. You should feel the benefits of an antihistamine, such as Allegra, within an hour.

Allegra should not be taken while taking other antihistamines such as Benadryl, Claritin or Zyrtec, unless recommended by your healthcare professional.

If you have any questions about Allegra and whether or not it is right for you or your children, talk to your health care provider.

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

  • “Fexofenadine and pseudoephedrine.” Medications and Supplements Aug 1 10. PubMed Health. United States National Library of Medicine.
  • “Allegra” Chattem 2011. Sanofi Pasteur.

By Kristina Duda, RN.

Kristina Duda, BSN, RN, CPN, has worked in healthcare since 2002. She specializes in pediatrics and disease and infection prevention.

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