Allegra vs. Benadryl: 8 Differences Between These Allergy Medications
Key takeaways:
Allegra (fexofenadine) and Benadryl (diphenhydramine) are both over-the-counter (OTC) antihistamines.
Both Allegra and Benadryl can help treat allergy symptoms. But Benadryl can also be taken for occasional sleep problems.
Allegra lasts longer in your body, so you don’t have to take it as often as Benadryl. Allegra also causes less drowsiness than Benadryl.
Allegra and Benadryl are available OTC as brand-name medications. But you can also find them as lower-cost generics. GoodRx can help make your medication more affordable.
Table of contents
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 your body longer to break down Allegra than Benadryl. This means you don’t need to take it as often.
Comparing options: Learn about the differences between the types of allergy medications so you can choose the right one for you.
What to expect: Drowsiness and headaches are just some of the notable antihistamine side effects.
More than medication: Three people share the daily lifestyle changes that have proven effective at reducing their allergy symptoms.
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.
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:
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Check in with your healthcare team if your sleep issues are ongoing. Don’t take Benadryl to help with sleep for more than 2 weeks unless a healthcare professional recommends this for you.
Keep in mind that 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 for adults and children age 12 and older. The dosage is lower for younger children.
Good to know: Benadryl can also help treat and prevent motion sickness. Allegra doesn’t work for this symptom.
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 age 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 a healthcare professional 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 pediatrician 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 (early) 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 prenatal care team 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 primary care 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 team 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. What’s more, it interacts with antacids that contain magnesium or aluminum. Taking Allegra with these foods, drinks, or medications can make it less effective. To avoid these interactions, separate these items 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 a healthcare professional write a prescription for OTC Allegra or Benadryl, GoodRx can help you save over 50% 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 $3.01 with a free GoodRx discount.
Frequently asked questions
Generally speaking, all oral antihistamines are considered similarly effective for managing allergies. But newer antihistamines, such as Allegra, cause less side effects than older ones, such as Benadryl. So experts typically recommend trying newer antihistamines first.
No, you shouldn’t take Allegra and Benadryl at the same time without a healthcare professional’s OK. Taking them together raises your risk of side effects because they work in similar ways. In severe cases, taking too many antihistamines at a time can lead to an overdose.
Grapefruit (and its juice), apple juice, orange juice, and green tea cannot be mixed with Allegra. You should also avoid taking it with antacids that contain aluminum or magnesium. Taking Allegra with these foods or medications can make it less effective. And don’t drink alcohol while taking Allegra. Mixing alcohol and Allegra can raise your risk of drowsiness and dizziness.
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 nondrowsy, but it’s not a first choice during pregnancy. Your healthcare team can help you decide which antihistamine is better for you.
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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?
Andersson, N. W., et. al. (2020). Association between fexofenadine use during pregnancy and fetal outcomes. Journal of the American Medical Association Pediatrics.
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Craun, K. L., et. al. (2024). Fexofenadine. StatPearls.
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Semla, T.P., et al (2023). American geriatrics society 2023 updated AGS beers criteria for potentially inappropriate medication use in older adults. Journal of the American Geriatrics Society.
Sicari, V., et al. (2023). Diphenhydramine. StatPearls.
Simon, F. E. R., et. al. (2008). H1 antihistamines: Current status and future directions. World Allergy Organization Journal.
The Procter & Gamble Manufacturing Company. (2024). ZzzQuil nighttime sleep-aid- diphenhydramine hydrochloride capsule, gelatin coated [package insert]. DailyMed.
