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Zyrtec vs. Benadryl: What's the Difference?

Edited by Janet White || By Harlon Moss || Updated on October 20, 2023
Zyrtec (cetirizine) and Benadryl (diphenhydramine) are antihistamines, but Zyrtec is a second-generation antihistamine while Benadryl is a first-generation antihistamine.

Key Differences

Zyrtec and Benadryl are both common antihistamine medications, but they belong to different generations. Zyrtec, whose generic name is cetirizine, is categorized as a second-generation antihistamine. This generation is known for its reduced tendency to cause drowsiness compared to its predecessors. On the flip side, Benadryl, with its generic name being diphenhydramine, is a first-generation antihistamine. These antihistamines easily cross the blood-brain barrier, which can often lead to drowsiness in users.
Another distinction between Zyrtec and Benadryl is their duration of action. While Zyrtec can offer up to 24 hours of relief from symptoms, Benadryl's effects typically last between 4 to 6 hours. This means that individuals using Benadryl might need to take it more frequently than those using Zyrtec. However, due to its sedative effects, Benadryl is sometimes used as a sleep aid in addition to its use for allergy relief.
Zyrtec's formulation primarily targets allergic reactions and provides consistent relief over an extended period. This makes it a preferred option for many with persistent allergies. In contrast, Benadryl is more than just an allergy medication; its diverse applications include aiding with insomnia, motion sickness, and even symptoms of Parkinson's disease.
While both Zyrtec and Benadryl are effective in combating allergy symptoms, they each have different side effects and drug interactions. It's always essential for individuals to consult with a healthcare professional to determine which medication is most suitable for their specific needs and conditions.

Comparison Chart

Generational Category

Second-generation antihistamine
First-generation antihistamine

Generic Name


Duration of Effect

Up to 24 hours
4 to 6 hours

Common Side Effects

Less likely to cause drowsiness
Often causes drowsiness

Other Uses

Primarily for allergies
Allergies, sleep aid, motion sickness

Zyrtec and Benadryl Definitions


An over-the-counter antihistamine used to treat allergy symptoms.
She took Zyrtec to alleviate her springtime hay fever.


A brand-name drug with the active ingredient diphenhydramine.
He found Benadryl effective against his seasonal allergies.


A medication often prescribed for perennial allergic rhinitis.
Her doctor recommended Zyrtec for her year-round allergies.


A medication commonly used for allergies, motion sickness, and sleep aid.
Before their road trip, she packed Benadryl to prevent motion sickness.


A popular brand-name drug with the active ingredient cetirizine.
He replaced his generic allergy pills with Zyrtec for consistent relief.


A versatile medicine also used to treat symptoms of Parkinson's disease.
In addition to allergies, Benadryl can also aid Parkinson's patients.


A non-sedating antihistamine that targets allergic reactions.
For her cat allergies, she always chooses Zyrtec.


A first-generation antihistamine known to cause drowsiness.
Benadryl helps her sleep when her allergies flare up at night.


A second-generation allergy medication known for its long-lasting effects.
Zyrtec provides her with relief throughout the day.


An over-the-counter antihistamine used to relieve allergic symptoms.
He took Benadryl after a bee sting to prevent severe reactions.


Antihistamine (trade name Benadryl) used to treat allergic reactions involving the nasal passages (hay fever) and also to treat motion sickness


Is Zyrtec less sedating than Benadryl?

Yes, Zyrtec is less likely to cause drowsiness compared to Benadryl.

Which lasts longer, Zyrtec or Benadryl?

Zyrtec generally lasts up to 24 hours, while Benadryl lasts 4 to 6 hours.

What's the generic name for Zyrtec?

The generic name for Zyrtec is cetirizine.

Can I take Zyrtec and Benadryl together?

It's not typically recommended due to potential side effects. Always consult a healthcare professional.

Are Zyrtec and Benadryl the same?

No, Zyrtec is a second-generation antihistamine, while Benadryl is a first-generation antihistamine.

Is Zyrtec safe for daily use?

Zyrtec is typically safe for daily use, but one should consult with a healthcare professional.

Can I take Zyrtec for skin allergies?

Yes, Zyrtec can be effective against skin allergies like hives.

Can I use Benadryl as a sleep aid?

Yes, Benadryl's sedative effects make it a common choice for a sleep aid.

What other uses does Benadryl have besides treating allergies?

Benadryl is also used for insomnia, motion sickness, and symptoms of Parkinson's.

Can children take Zyrtec?

Yes, but always consult with a healthcare professional for appropriate dosing.

What type of allergies is Zyrtec most effective against?

Zyrtec effectively treats indoor and outdoor allergies.

Are there non-drowsy versions of Benadryl?

Traditional Benadryl is known for its sedative effects, but there are other antihistamines available that are non-drowsy.

How should I store Benadryl?

Benadryl should be stored at room temperature, away from light and moisture.

How often should I take Benadryl?

Benadryl typically lasts 4 to 6 hours, but always follow dosing recommendations.

Are there side effects to Zyrtec?

Zyrtec can have side effects, including headache, stomach pain, and dry mouth.

Is it safe to drive after taking Benadryl?

Due to its sedative effects, one should avoid activities requiring alertness after taking Benadryl.

How does Zyrtec reduce allergy symptoms?

Zyrtec works by blocking histamine, a substance in the body responsible for allergic reactions.

What's the difference between children's Benadryl and regular Benadryl?

The primary difference is the dosing amount and sometimes the formulation.

How soon does Zyrtec start working?

Zyrtec typically starts working within an hour of ingestion.

What's the primary active ingredient in Benadryl?

The primary active ingredient in Benadryl is diphenhydramine.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.

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