Allegra vs Claritin: What’s the Difference?

As much as we love to feel the weather warm up in the spring and cool off in the fall, for many people, seasonal changes mean seasonal allergies. For others, there is no relief in sight no matter what season it is, because their allergy symptoms persist year round.

Over 50 million Americans deal with allergies throughout the year, which makes allergies the sixth most common chronic illness in the United States; the most common health issue for children in the U.S. is allergies.

People looking for long-term relief from their seasonal or perennial allergy symptoms often turn to over the counter, or OTC, medications like Benadryl, Cetirizine and more commonly, Allegra and Claritin for decongestant relief.

While these medications once required a prescription, today, they are available over the counter and offer accessible, affordable relief to millions. If you’re trying to decide between Allegra vs Claritin, you should know the differences between the two medications. 

Drug Class

Both FDA approved, Allegra and Claritin both belong to a class of drugs known as antihistamines; specifically, the two medications are considered second generation antihistamines.

Second-generation antihistamines were developed because the first generation of antihistamines treated allergies, and specifically, allergic rhinitis, effectively, but caused severe drowsiness as a side effect.

Therefore, the medications were not safe to take when driving or operating heavy machinery, and many people could not perform daily activities while taking the medications.

Second generation antihistamines like Allegra and Claritin provide relief from symptoms of allergic rhinitis without the high potential for drowsiness associated with first generation antihistamines.

The active ingredient in Allegra is fexofenadine, while the active ingredient in Claritin is loratadine.

Conditions Treated

Allegra and Claritin are both intended for the treatment of allergic rhinitis, a group of symptoms that impacts the sinus and the nose when a person is exposed to an allergen.

Allergens are normal substances in the environment that generally do not cause problems for most people but causes a strong reaction in a person with allergies

While allergens will not cause a reaction in most people, the immune system of a person with allergies responds to the presence of allergens by attacking them.

Inflammatory mediators, called histamines, are released during an allergy attack, and they then bind to receptors on other cells in the body.

Upon binding to the receptors, histamines cause allergy symptoms like runny nose, sinus pressure, nasal congestion, sneezing, itchy/watery eyes, and itchy nose or throat.

There are many different triggers for allergic rhinitis, including both indoor and outdoor allergens. Outdoor allergens include things like grass, flower, tree, or weed pollen, while indoor allergens include pet dander or hair, mold, dust mites, perfume, and smoke.

Allergic rhinitis is most often experienced seasonally when a person is allergic to outdoor allergens, while people with allergies to indoor substances are likely to experience symptoms year round.

It’s possible to experience both perennial and seasonal allergic rhinitis, depending on the specific allergens that cause symptoms in an individual.

How it Works

Second generation antihistamines like Claritin and Allegra work by blocking the effects of histamines on the body. 

Both medications bind to histamine receptors in the body, such as anticholinergic, which in turn prevents the cells from sending messages that cause symptoms like itching, sneezing, and increased production of mucus.

When taken regularly, the medications can reduce the number of histamines produced by the body in response to allergens over a long period of time. 


One of the main differences between Claritin and Allegra is that the two medications come in different forms.

Allegra is produced in the form of an orally disintegrating tablet, oral suspension, oral tablet, and oral capsule, while Claritin is made as an orally disintegrating tablet, oral tablet, oral capsule, chewable tablet, and oral solution.

Depending on the form the medication is purchased in, Claritin and Allegra may be used for children and adults as young as 2 years old (chewable tablet and oral solution and oral suspension, respectively).

Orally disintegrating tablets are recommended for children and adults ages 6 and older for both medications. Another significant difference is that Allegra is approved only for children and adults ages 12 and older in its oral tablet and oral capsule forms, while Claritin is approved for children ages 6 and older in these forms. 


Although Claritin is classified as an antihistamine, it is not approved for the treatment or prevention of all types of allergic reactions.

Claritin is used to treat symptoms associated with allergic rhinitis, or hay fever; these symptoms include itching, runny nose, watery eyes, and sneezing. Claritin is also used to provide relief from itching caused by hives.

However, Claritin cannot treat or prevent all allergic reactions. Claritin is not approved for the prevention of hives or the treatment or prevention of a serious allergic reaction, including those caused by food, insect stings, and other serious allergies.

Claritin is used to treat the usually minor symptoms associated with allergic rhinitis, which can occur seasonally or on a year-round basis.


Everyone wants to take the most effective allergy medication possible, so one of the major questions about the differences between Claritin and Allegra is: which is more effective?

Like so many things in medicine, the answer is “it depends.” When it comes to overall effectiveness, it appears that Claritin is more effective in treating allergic rhinitis than Allegra because it provides more complete symptom relief and works more quickly.

However, Allegra has been shown to provide more eye symptom relief, including relief of itchy, watery eyes, and is more effective at treating wheal and flare reactions, an allergic skin reaction. By contrast, Claritin is better suited for treating hives.

Allegra has been shown to have the lowest risk of sedation and drowsiness out of all antihistamines, so it is preferred in situations where alertness is important, such as when taken by people with safety-critical jobs.


Because both Allegra and Claritin can be taken over the counter, the risks associated with both medications are considered mild.

However, there is one notable difference between the risks of the medications: Allegra should not be taken with grapefruit juice.

It is believed that the active ingredient in Allegra, fexofenadine, has the rate and extent of its absorption decreased by approximately 30 percent when taken with grapefruit or grapefruit products, such as juice. There are no known food interactions associated with Claritin.

 Side Effects

If you’ve ever taken an antihistamine before, you’re likely already familiar with some of the common side effects of Claritin, which include:

  • Headache
  • Sleepiness
  • Feeling tired
  • Drowsiness
  • Fatigue
  • Nervousness
  • Stomach pain
  • Diarrhea
  • Dry mouth
  • High blood pressure
  • Sore throat
  • Hoarseness
  • Eye redness
  • Blurred vision
  • Nosebleed
  • Skin rash

Mild side effects associated with Allegra-d include:

  • Headache
  • Trouble sleeping
  • Vomiting
  • Nervousness

Serious side effects associated with Claritin-d can include:

  • Allergic reactions
  • Feeling like you might pass out
  • Unsafe heart beat
  • Jaundice (yellowing of the skin or eyes)
  • Increased heart rate
  • Seizures (convulsions)

Serious side effects associated with Allegra include:

  • Swelling of the face, eyes, lips, throat, tongue, hands, feet, arms, ankles, and lower legs
  • Trouble swallowing or breathing
  • Chest tightness
  • Flushing (a sudden reddening or warming of the skin)

It is rare, but Allegra and Claritin can both cause allergic reactions in people who are allergic to their active ingredients. Signs of an allergic reaction include hives, difficulty breathing, or swelling of your face, lips, tongue, or throat and require immediate medical attention.

Drug interactions

Although Allegra and Claritin are sold over the counter, both do have some drug interactions. Both Allegra and Claritin interact with ketoconazole and erythromycin, so you should not take those medications when taking Allegra or Claritin.

Allegra can also interact with antacids, while Claritin can interact with a medication called amiodarone.

In order to avoid drug interactions, it is best to talk with your doctor prior to trying any new medication, including over the counter medications.

Make sure to give your doctor a complete list of all prescription and over the counter drugs you are taking, as well as any vitamins or supplements you take or herbs that you use regularly.


The choice between whether to take Allegra or Claritin ultimately comes down to your individual symptoms and needs. People with significant sinus symptoms and allergic rhinitis may be best suited to taking Claritin, which is believed to be more effective in treating symptoms of allergic rhinitis.

However, those with worse eye symptoms or skin reactions may find more relief with Allegra.

People with safety-critical jobs or for whom drowsiness is a significant concern should take Allegra, as it has been shown to have the lowest sedation effect of any antihistamine.

However, both medications are effective for the treatment of perennial and seasonal allergic rhinitis and will provide relief at an affordable price. 








medically reviewed and fact checked