What You Should Know About Allegra

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

young woman suffering spring allergy and blowing nose with a tissue in the nature
raquel arocena torres / Getty Images

Active Ingredient

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

Dosing Information

Several forms of Allegra are available.

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

Allegra 12-hr 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.

(t is important to note that decongestants should not be taken long-term, so if you choose to take Allegra-D, do not take it for more than a few days before switching to a medication that does not contain a decongestant.)

There re several formulations of Children's Allegra that are available over-the-counter. Dosing varies according to the type of Allegra. Refer to box to determine the precise dose of medication required based on the age of your child.

Allegra should not be taken at the same time as fruit juices.

Allegra should be taken on an empty stomach with a full glass of water. Taking it with fruit juice could 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 involved with taking Allegra. Talk to your healthcare provider before you take 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 usually not cause drowsiness. Certain serious side effects should not be ignored. If you experience any of the following, contact your healthcare provider right away.

Who Shouldn't Take It

Certain people should not take Allegra. Do not take it if you are allergic to any of the ingredients in Allegra.

What You Need 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 when you are taking other antihistamines such as Benadryl, Claritin or Zyrtec unless recommended by your healthcare provider.

If you have questions about Allegra and whether or not it is right for you or your children, consult your healthcare provider.

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.
  • "Fexofenadine and Pseudoephedrine." Drugs and Supplements 1 Aug 10. PubMed Health. US National Library of Medicine.
  • "Allegra" Chattem 2011. Sanofi Pasteur.

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