Compare Allegra vs. Benadryl

Head-to-head comparisons of medication uses, side effects, ratings, and more.

Allegra
(Fexofenadine)

Benadryl
(Diphenhydramine)

Treats allergy symptoms. Allegra (Fexofenadine) relieves allergy symptoms without making you feel drowsy.Treats allergy symptoms and helps you sleep. Benadryl (Diphenhydramine) is great for allergies, but curl up on the couch after taking it and get ready for a nap.
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Reviews & ratings
Button Group. All currently active
Button Group. All currently active
5.2727272727272725Allegra
Reviews for Allegra (Fexofenadine)
77%
of people say Allegra (Fexofenadine) is worth it
59%
say it works well
0%
say it's a big hassle
Reviews for Benadryl (Diphenhydramine)
85%
+8% vs. Allegra (Fexofenadine)
57%
2% vs. Allegra (Fexofenadine)
8%
8% vs. Allegra (Fexofenadine)
Side effects
AllegraBenadryl
  • Vomiting 3%
  • Headache 3%
  • Cough 3%
  • Back pain 2%
  • Ear, nose, or throat infection 2%
  • Diarrhea 1%
  • Fever 1%
  • Runny nose 1%
  • Dizziness 1%
  • Stomach discomfort 1%
More Allegra side effects »

We haven’t found good data for Benadryl side effects.

FDA side effect reports for Benadryl »
How it works
AllegraBenadryl
Allegra (Fexofenadine) is an antihistamine. It blocks histamine, a chemical that causes congestion, itching, and other allergic reactions.Benadryl (Diphenhydramine) is an antihistamine. It blocks histamine, a chemical that causes congestion, itching, and other allergic reactions. It also makes you sleepy.
Type of medication
AllegraBenadryl
Antihistamine
2nd generation
Prescription or OTC
Antihistamine
1st generation
Prescription or OTC
Available as
AllegraBenadryl
  • Pill
  • Dissolving tablet
  • Liquid
  • Pill
  • Oral solution
  • Cream, gel, or ointment
Used for (click to learn more)
AllegraBenadryl
Risk factors for serious side effects
AllegraBenadryl
  • Taking with alcohol
  • Taking other medicines that make you less alert
  • History of phenylketonuria (PKU)
Detailed Allegra (Fexofenadine) risks & warnings »
  • Using other drugs with the same ingredients
  • Age 65 years or older
  • Taking with alcohol
  • Taking other medicines that make you less alert
  • Children age 6 years and younger
  • Enlarged prostate
  • History of bladder problems
  • Glaucoma
  • Nursing mothers
Detailed Benadryl (Diphenhydramine) risks & warnings »
Pregnancy category
AllegraBenadryl
CFDA pregnancy category (Weigh risks vs. benefits)

Research studies with animals found harmful effects on unborn babies. It hasn’t been properly studied in humans. The benefits might outweigh the risks even if you’re pregnant. Talk with your doctor.

See the FDA package insert
BFDA pregnancy category (Probably safe)

Research studies with animals haven’t found a risk to unborn babies, but it hasn’t been properly studied in humans.

See the FDA package insert
Alcohol
No specific alcohol-related info.
  • Don't take it with alcohol or other drugs that make you sleepy.
Food
No specific food-related info.No specific food-related info.
Kidneys and liver
  • The dose needs to be adjusted for people with kidney problems.
No specific kidneys and liver-related info.
Sex
No specific sex-related info.No specific sex-related info.
Sleep
  • Won't make you feel drowsy like some antihistamine medicines.
  • Benadryl (Diphenhydramine) makes you tired, so take it before you go to sleep.
  • People age 65 years and older have a higher risk of side effects from taking antihistamine medications like Benadryl (Diphenhydramine). Watch for changes in vision, severe dry mouth, trouble urinating, or constipation. The drowsiness caused by Benadryl (Diphenhydramine) can make you "unsteady" on your feet, leading to a higher chance of falls.
Weight
No specific weight-related info.No specific weight-related info.
Upsides and benefits
AllegraBenadryl
  • Relieves allergy symptoms, like sneezing, runny nose, and itching.
  • Approved to be used in kids and adults age 6 months and older.
  • Won't make you feel drowsy like some antihistamine medicines.
  • Available over-the-counter without a prescription.
  • Comes in many forms, such as a tablet, liquid, or quick-dissolving tablet.
  • It's okay to take with most other medications since it has very few interactions.
  • Benadryl (Diphenhydramine) is often better than other antihistamines at treating allergy symptoms and hives.
  • It can provide quick relief of allergy symptoms for both kids and adults.
  • It makes you sleepy, so it'll help if your allergies are bothering you at night.
  • The effects wear off in 4 to 6 hours, so side effects don't last that long.
  • It comes as a tablet, capsule, liquid, and quick dissolving tablet.
Downsides and risks
AllegraBenadryl
  • For some people, the effects Allegra (Fexofenadine) has on allergies will wear off over time.
  • May not work as well as the first-generation antihistamines, like diphenhydramine (Benadryl).
  • The dose needs to be adjusted for people with kidney problems.
  • Benadryl (Diphenhydramine) makes you more tired than Claritin, Allegra, or Zyrtec.
  • You shouldn't drive after taking Benadryl (Diphenhydramine) until you know how it affects you.
  • Talk to a pediatrician before giving Benadryl (Diphenhydramine) to a child.
  • It can increase the risk of falls, so elderly people shouldn't use Benadryl (Diphenhydramine).
  • Don't use Benadryl (Diphenhydramine) if you are breastfeeding.
Tips from our pharmacists for people taking the medication
AllegraBenadryl
  • Starts working in 1 to 2 hours depending on what dosage form you're taking.
  • Works best when taken regularly, even before symptoms are expected to appear.
  • Can make you feel dizzy or sleepy, so you can take it at bedtime.
  • Follow age-specific dosing and don't take more than recommended.
  • If symptoms get worse or you need to use it for more than a few weeks, talk with your doctor.
  • Take it as needed every 4 to 6 hours.
  • Benadryl (Diphenhydramine) can make you dehydrated, so avoid this side effect by drinking plenty of fluids.
  • Benadryl (Diphenhydramine) makes you tired, so take it before you go to sleep.
  • Don't take it with alcohol or other drugs that make you sleepy.
  • If you need to use it for more than a few weeks, talk with your doctor. A different medication might work better for you long-term.
  • If you only have itchy or watery eyes, try using just an antihistamine eye drop.
Learn more
More about AllegraSide effectsReviews & ratingsAlternativesFDA package insert
More about BenadrylSide effectsReviews & ratingsAlternativesFDA package insert