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If you have seasonal allergies (hay fever), you know all about the aggravating symptoms they can cause, from a runny or congested nose to watery eyes, sneezing, and itching. These symptoms occur when you’re exposed to allergens such as:
- trees
- grass
- weeds
- mold
- dust
Allergens cause these symptoms by prompting certain cells throughout your body, called mast cells, to release a substance called histamine. Histamine binds to parts of cells called H1 receptors in your nose and eyes. This action helps open blood vessels and increase secretions, which helps protect your body from allergens. However, that doesn’t mean you’ll enjoy the resulting runny nose, watery eyes, sneezing, and itching.
Allegra and Claritin are over-the-counter (OTC) medications that can help relieve allergy symptoms. They’re both antihistamines, which work by blocking histamine from binding to H1 receptors. This action helps prevent your allergy symptoms.
While these drugs work in a similar way, they’re not identical. Let’s look at some of the main differences between Allegra and Claritin.
Some of the key features of these drugs are the symptoms they treat, their active ingredients, and the forms they come in.
- Symptoms treated: Both Allegra and Claritin can treat the following symptoms:
- sneezing
- runny nose
- itchy, watery eyes
- itchy nose and throat
- Active ingredients: The active ingredient in Allegra is fexofenadine. The active ingredient in Claritin is loratadine.
- Forms: Both drugs come in a variety of OTC forms. These include an orally disintegrating tablet, oral tablet, and oral capsule.
Claritin also comes in a chewable tablet and oral solution, while Allegra also comes as an oral suspension.* However, these forms are approved to treat different ages. If you’re treating your child, this could be an important distinction in making your choice.
Note: Don’t use either drug in children who are younger than the form is approved for.
| Form | Allegra Allergy | Claritin |
| Orally disintegrating tablet | ages 6 years and older | ages 6 and older |
| Oral suspension | ages 2 years and older | — |
| Oral tablet | ages 12 years and older | ages 6 years and older |
| Oral capsule | ages 12 years and older | ages 6 years and older |
| Chewable tablet | — | ages 2 years and older |
| Oral solution | — | ages 2 years and older |
For specific dosage information for adults or children, read the product package carefully or talk to your doctor or pharmacist.
*Solutions and suspensions are both liquids. However, a suspension needs to be shaken before each use.
Allegra and Claritin are considered newer antihistamines. One benefit of using a newer antihistamine is that they’re less likely to cause drowsiness than older antihistamines.
The other side effects of Allegra and Claritin are similar, but in most cases, people don’t experience any side effects with either drug. That said, the following tables list examples of possible side effects of these drugs.
| Mild side effects | Allegra Allergy | Claritin |
| headache | ✓ | ✓ |
| trouble sleeping | ✓ | ✓ |
| vomiting | ✓ | |
| nervousness | ✓ | ✓ |
| dry mouth | ✓ | |
| nosebleed | ✓ | |
| sore throat | ✓ |
| Possible serious side effects | Allegra Allergy | Claritin |
| swelling of your eyes, face, lips, tongue, throat, hands, arms, feet, ankles, and lower legs | ✓ | ✓ |
| trouble breathing or swallowing | ✓ | ✓ |
| chest tightness | ✓ | |
| flushing (reddening and warming of your skin) | ✓ | |
| rash | ✓ | |
| hoarseness | ✓ |
If you experience any serious side effects that may indicate an allergic reaction, get emergency medical treatment right away.
Two things you should consider when taking any medication is the possible drug interactions and potential problems related to health conditions you have. These are not all the same for Allegra and Claritin.
Drug interactions
A drug interaction occurs when a medication that’s taken with another drug changes the way that drug works. This can be harmful or prevent the drug from working well.
Allegra and Claritin interact with some of the same drugs. Specifically, each may interact with ketoconazole and erythromycin. But Allegra can also interact with antacids, and Claritin can also interact with amiodarone.
To help avoid interactions, be sure to tell your doctor about all prescription and OTC drugs, herbs, and supplements you take. They can tell you about what interactions you might be at risk of in using Allegra or Claritin.
Health conditions
Some drugs aren’t a good choice if you have certain health conditions.
For example, both Allegra and Claritin can cause problems if you have kidney disease. And certain forms may be dangerous if you have a condition called phenylketonuria. These forms include the orally disintegrating tablets of Allegra and the chewable tablets of Claritin.
If you have either of these conditions, talk to your doctor before taking Allegra or Claritin. You should also talk to your doctor about the safety of Claritin if you have liver disease.
Both Claritin and Allegra work well to treat allergies. In general, they’re tolerated well by most people. The main differences between these two medications include their:
- active ingredients
- forms
- possible drug interactions
- warnings
Before taking either medication, talk to your doctor or pharmacist. Work with them to choose the one that’s best for you. You might also ask what other steps you can take to help reduce your allergy symptoms.