Zyrtec or Benadryl? Pros & Cons of Each (for Allergy Treatment)

If you have ever noticed that you sneeze, wheeze, or get a runny nose after being in an attic or in the springtime, you may have allergies. There are various treatment options available to provide relief, including Zyrtec and Benadryl. (Learn More)

For many, an over-the-counter antihistamine can do the trick and provide a necessary sense of comfort. (Learn More) Both medications come with the potential for some side effects, such as fatigue, dry mouth, and stomach issues. (Learn More)

The choice between Zyrtec and Benadryl is a personal one. Either Zyrtec or Benadryl may work better for you. (Learn More)

woman with allergies

What Do Zyrtec and Benadryl Treat? 

When you have an allergic reaction, your body dispenses histamines. And these histamines actually cause allergies when they attach to certain components in a cell.

Both Zyrtec and Benadryl belong to a family of drugs called antihistamines. They mitigate the symptoms of allergies by treating symptoms caused by hay fever and other allergic reactions to substances like cockroaches, mold, dust mites, or pet dander.

Hay fever (an allergy to airborne items such as pollen) may cause these symptoms:

  • Runny nose
  • Watery eyes
  • Itchiness in the throat or nose
  • Sneezing

Both Benadryl and Zyrtec are sold over the counter (OTC). This means you do not need a prescription to buy them.

You are encouraged to discuss your use of either medication with your doctor, especially if you do not feel they are working properly or to clarify anything you might need to know.

Benadryl can also treat insomnia, the common cold, and motion sickness.

Effectiveness of Zyrtec & Benadryl 

While known to be effective for the symptoms of airborne allergens, Benadryl or Zyrtec do not treat the root causes of these allergies. Even so, both of these medications are known to be effective antihistamines that help many allergy sufferers feel better, especially during spring.

Zyrtec normally works within an hour of taking it. It can also be taken every day to prevent allergic reactions as needed.

Benadryl comes in a variety of forms. There’s even a topical form of the medication for people who have hives.

Side Effects of Zyrtec & Benadryl

 OTC medications can trigger side effects, just like any prescription drug. It is a good idea to discuss your use of OTC medications, prescription medications, and even herbal supplements with your doctor prior to taking Benadryl or Zyrtec.

Read all directions on the box, and remember that side effects are possible.

Zyrtec Side Effects

  • Fatigue
  • Dry mouth
  • Dizziness
  • Abdominal pain
  • Vomiting
  • Diarrhea

Zyrtec is known to be safe during pregnancy, but women may experience worse symptoms than usual during their pregnancy. Not everyone experiences changes in their allergies during pregnancy, but it is important to anticipate this and prepare.

Exercise additional precautions when administering Zyrtec to children.

Benadryl Side Effects

  • Dry mouth
  • Decreased appetite
  • Vomiting
  • Constipation
  • Headache
  • Muscle weakness
  • Hyperactivity (especially in children)
  • Difficulty urinating
  • Vision issues

Benadryl is known to cause strong side effects in children and can even be lethal for children under the age of 4. Use extra precaution in children between ages 4 and 11.

Be careful when drinking alcohol if taking Benadryl. Healthline says that Benadryl, like alcohol, is known for its sedative effects. Alcohol and Benadryl can quickly depress your central nervous system (CNS), making it harder for you to complete tasks that require your total attention, such as driving or operating heavy machinery.

Benadryl can be used as a sleep aid if your doctor signs off on this. However, the combination of alcohol and Benadryl may make it harder for you to go to sleep


Pros & Cons of The Medications

There are advantages and disadvantages to both Zyrtec and Benadryl.

Some disadvantages of taking Benadryl are:

  • Side effects. Both medications are known to have side effects, but the list of side effects for Benadryl is slightly longer. Precautions for its use in children are much stricter than they are for Zyrtec.
  • Drowsiness. Benadryl is known to make people especially sleepy. People need to avoid alcohol when taking Benadryl, as the combination can lead to excessive sleepiness.
  • Association with dementia. Harvard Medical School reported on a study that links use of Benadryl to dementia after tracking frequent use of the medication over a seven-year period. Benadryl works by blocking acetylcholine, which has an effect on muscle contractions as well as memory and learning.

A major advantage of Benadryl is its varied uses. It can be used for motion sickness, insomnia, and allergies.

For Zyrtec, some known disadvantages are:

  • Side effects. It still offers many of the same side effects as Benadryl, but they can be less severe.
  • Limited use. Zyrtec is only meant to be used as an allergy treatment.

Known advantages of Zyrtec are:

  • Its fast method of action. Zyrtec can work in about an hour.
  • Safety during pregnancy. Zyrtec is known to be safe to take during pregnancy as needed.

Frequently Asked Questions 

What conditions do Zyrtec and Benadryl treat?

Both medications are known for their treatment of allergies caused by airborne agents, such as pollen and dust. But Benadryl can also treat insomnia, and its topical form can treat hives.

How effective are Zyrtec and Benadryl?

Zyrtec and Benadryl are both known to work in patients with allergies. However, everyone is different. You may have to try both medications to see which one best deals with your symptoms.

Are there any side effects to these medications?

Yes, Zyrtec and Benadryl are both known for causing dry mouth, vomiting, and fatigue. Zyrtec specifically causes stomach pain in some people.

Benadryl is known for its stronger fatigue levels. It is also known to cause hyperactivity in children.

What are the advantages and disadvantages of these medications?

Both medications are available over the counter, which makes it easier for patients to get the care they need. Zyrtec does have side effects, but one major edge it has over Benadryl is that its side effects are less severe.

Benadryl is known to properly treat allergy symptoms, but it is also associated with drowsiness. You should abstain from alcohol when taking Benadryl, as both substances can have a depressant effect.

Children between the ages of 4 and 11 might be able to take Benadryl, but it can cause serious side effects in children under 4 years old. Benadryl can also be fatal in young children.


Common Anticholinergic Drugs Like Benadryl Linked to Increased Dementia Risk. (January 2015). Harvard Medical School.

Is It Safe to Mix Benadryl and Alcohol? (April 2018). Healthline.

Cetirizine. (January 2018). MedlinePlus.

Using Zyrtec for Treating Hives and Allergies. (May 2019). Verywell Health.

Diphenhydramine. (August 2018). MedlinePlus.

Allergies. (January 2018). Mayo Clinic.

Popular Over-the-Counter Oral Antihistamine Brands. (April 2018). Healthline.

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