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Allegra (fexofenadine) and Benadryl (diphenhydramine) are two antihistamines available over the counter (OTC). They can both help relieve allergy symptoms in adults and children. But they have some notable differences.

For instance, Benadryl is a first-generation (older) antihistamine, while Allegra is a third-generation (newer) antihistamine. This distinction means that Allegra tends to have fewer side effects, among other unique qualities.

When faced with choosing which antihistamine to take, knowing what sets them apart can help you make an informed decision. Let’s review eight differences between Allegra and Benadryl that can help you select the one that’s right for you.

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1. Allegra lasts longer than Benadryl

If you’re looking for long-lasting allergy relief, Allegra might be a better option. Most people take Allegra once or twice a day. You may need to take Benadryl every 4 to 6 hours for continued relief.

It typically takes the body longer to break down Allegra than Benadryl. This means you don’t need to take it as often.

2. Allegra is considered nondrowsy

You’re likely familiar with Benadryl’s reputation for causing drowsiness as a side effect. But how does Allegra compare? In short, Allegra doesn’t usually cause drowsiness.

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Allegra is the antihistamine with the lowest risk of drowsiness. This is because it doesn’t easily cross the blood-brain barrier (cells surrounding the brain that protect it). On the flip side, Benadryl easily crosses the blood-brain barrier. Medications that pass through this barrier can cause brain-related side effects, such as drowsiness.

It’s important to note that Allegra may still cause drowsiness for a small number of people who take it. But the risk of this is very low. So if you’re looking for a nondrowsy antihistamine, Allegra is a better option than Benadryl.

3. Benadryl can also be used for occasional sleep troubles

If you’re having trouble sleeping, the drowsiness caused by Benadryl might be helpful. Unlike Allegra, Benadryl can be taken for occasional sleep troubles. In fact, diphenhydramine (Benadryl’s active ingredient) is included in many OTC sleep aids for people age 12 and older.

Examples of popular sleep aids that contain diphenhydramine include:

• Unisom SleepMinis
• Simply Sleep
• ZzzQuil

Check in with your healthcare provider if your sleep issues are ongoing. Benadryl shouldn’t be taken for sleep for more than 2 weeks unless your provider recommends this for you.

Keep in mind: The dosage of Benadryl that’s taken for sleep is different from the dosage for allergies. For sleep, the usual dosage of Benadryl is 50 mg taken 30 minutes before bedtime. For allergies, it’s typically 25 mg to 50 mg every 4 to 6 hours.

4. Allegra is safer for older adults

Benadryl can cause serious side effects in older adults. These may include:

• Confusion
• Higher risk of falls
• Severe drowsiness
• Difficulty urinating
• Constipation

Because of these risks, the American Geriatrics Society recommends adults ages 65 and older avoid Benadryl and other first-generation antihistamines. Taking Allegra for allergies is a safer alternative because it typically causes fewer side effects.

Good to know: If you’ve had allergic reactions in the past, ask your healthcare provider which medication is best for you to have on hand in case it happens again. They may recommend Benadryl in certain situations. But severe allergic reactions require epinephrine (used in EpiPens) and emergency medical attention.

5. Allegra has dosage information for kids as young as 2 years old

If you look in your local pharmacy, you’ll find both Allegra and Benadryl products marketed for kids. But you’ll also notice on the medication’s label that there’s a difference in age ranges for each product.

Certain forms of Allegra can be safely given to children as young as 2 years old. On the other hand, Benadryl only provides dosage information for children age 6 and older. So Allegra may be a better choice for allergy symptoms if your child is between the ages of 2 and 5 years old.

If you believe your child needs Benadryl and is under 6 years old, check with their healthcare provider first. Depending on your child’s symptoms, they may still recommend giving it. But they’ll be able to provide you with a safe dosage based on your child’s age and body weight.

6. Benadryl might be preferred during pregnancy

Figuring out which medications are safe during pregnancy can feel overwhelming. When it comes to antihistamines, some have more safety data than others.

In a study looking at pregnancies in Denmark from 2001 through 2016, Allegra wasn’t linked to a higher risk of birth defects, miscarriage, or preterm birth. But it has less safety data available than Benadryl, which has extensive evidence for its use during pregnancy.

Allegra was also found to cause low birth weight in animal studies. This link hasn’t been found in human studies. But for these reasons, Allegra isn’t considered a first choice for treating allergies during pregnancy.

Both the American College of Allergy, Asthma and Immunology and the American College of Obstetricians and Gynecologists consider first and second-generation antihistamines generally safe during pregnancy. Zyrtec (cetirizine) and Claritin (loratadine) are two second-generation options that have more safety data available than Allegra.

If you’re pregnant, it’s always best to speak with your provider about which allergy medication is the best choice for you. They’ll take your symptoms, medical history, and unique risks into account when recommending something.

7. Benadryl also comes available as a cream

Both Allegra and Benadryl are available in many different formulations, including tablets, capsules, and oral liquids. But Benadryl also comes as a topical cream that’s applied to the skin. This might be helpful for insect bites, minor burns, or other mild skin irritations. But it won’t help with allergy symptoms that aren’t associated with your skin, such as sneezing.

Topical Benadryl typically has fewer side effects compared to oral dosage forms. It also provides relief only where you need it instead of affecting your whole body. Your healthcare provider or pharmacist can help you decide if topical Benadryl would be a better fit for your symptoms.

8. Allegra and Benadryl have different interactions

Allegra and Benadryl have different chemical properties. This means they interact with other substances in different ways. It’s important to share a list of your current medications with your healthcare provider and pharmacist so they can screen for interactions.

Allegra is known to interact with grapefruit (the juice and the fruit itself). It also interacts with apple juice, orange juice, and green tea. Taking Allegra with these foods or drinks can make it less effective. To avoid these interactions, separate these foods and drinks from Allegra by at least 4 hours.

Benadryl doesn’t have the same dietary restrictions as Allegra. But it does have important interactions to know about.

Alcohol can cause Benadryl’s side effects, such as drowsiness, to be more intense. Benadryl also interacts with other medications that cause drowsiness. Some examples include sleep medications, opioid pain medications, and benzodiazepines (a type of anxiety medication).

In general, you should avoid taking any antihistamine with alcohol or medications that cause drowsiness. But the risk of complications is much lower with Allegra than with Benadryl.

How to save on Allegra and Benadryl

There are many ways to save on Allegra and Benadryl, which are available as both brand-name and generic medications. By having your healthcare provider write a prescription for OTC Allegra or Benadryl, GoodRx can help you save over 60% off the average retail price.

Generic Allegra’s price at certain pharmacies is as low as $7.66 with a free GoodRx coupon. Generic Benadryl’s price at certain pharmacies is as low as $0.68 with a free GoodRx discount.

The bottom line

When choosing between Allegra (fexofenadine) and Benadryl (diphenhydramine), you should consider their uses, potential side effects, and interactions. Both Allegra and Benadryl treat allergy symptoms. But Benadryl can also help with occasional sleep troubles.

Benadryl tends to cause more drowsiness and should be avoided by older adults. Allegra is longer lasting and non-drowsy, but it’s not a first choice during pregnancy. Your healthcare provider or pharmacist can help you decide which antihistamine is better for you.

Why trust our experts?

Written by:

Kristianne Hannemann, PharmD

Kristianne Hannemann, PharmD, is a licensed pharmacist in California. She has been a retail pharmacy manager and staff pharmacist for over 7 years and has contributed drug information content to different health companies.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Daphne Berryhill, RPh

Daphne Berryhill, RPh, has two decades of experience as a clinical pharmacist. She spent most of her career in the Chicago area practicing in-home infusion.

Our editorial standards

References

American College of Allergy, Asthma, and Immunology. (2018). Pregnancy and allergy: Practical tips for pregnant patients with asthma or other allergic conditions.

American College of Obstetricians and Gynecologists. (2021). What medicine can I take for allergies while I’m pregnant?