Can You Take Zyrtec and Benadryl Together?

Medically reviewed by Femi Aremu, PharmD

Zyrtec (cetirizine) and Benadryl (diphenhydramine) are antihistamines that relieve allergy symptoms such as sneezing, itching, runny nose, and watery eyes.

Taking Zyrtec and Benadryl together is generally not recommended without consulting a healthcare provider or pharmacist, as they belong to the same class of medications called antihistamines.

Combining these drugs can increase the risk of side effects such as drowsiness, dizziness, and impaired coordination.

If your allergy symptoms are not well controlled with one antihistamine alone, it's important to seek medical advice rather than self-medicating with both drugs simultaneously. A healthcare professional can recommend alternative approaches or different medications.

This article will discuss using Zyrtec and Benadryl and the precautions for combining medications to help manage your allergies.

How Are Zyrtec and Benadryl Used?

Zyrtec or Benadryl are antihistamines that can treat allergies or allergic reactions that cause a stuffy or runny nose, watery red eyes, and sneezing. Both medications are generally safe and effective when taken alone.

Benadryl was created in the 1940s and is considered a first-generation antihistamine. It has a lot of sedating effects that can cause drowsiness, tiredness, and fatigue for many first-time users.

In 1995, Zyrtec came to the market. As a newer medication for allergies, it was considered a second-generation anti-allergy medication with less sedating effects.

Second-generation allergy medications are generally preferred over first-generation ones due to the lower risk of sedating effects.

Can I Take Zyrtec and Benadryl Together?

You should not combine multiple antihistamine medications, such as Zyrtec and Benadryl.

Taking these medications at the same time could increase your risk of side effects, such as:

• Sedation

• Unable to operate machinery (especially at night)

• Dizziness

• Dry eyes

• Constipation

Zyrtec alone can give 12 to 24 hours of allergy relief. However, in some cases, you may need additional relief. Talk to your primary care provider before starting another medication to see what is best for you.

How Long After Taking Zyrtec Can I Take Benadryl

Zyrtec can work in your body for 12 to 24 hours at most.

After taking Zyrtec, you should wait at least 24 hours before taking Benadryl or another antihistamine. However, Benadryl only lasts in the body for four to six hours. Therefore, if you've taken Benadryl, you only need to wait six hours after your dose to take Zyrtec.

How Much Zyrtec or Benadryl Should I Take?

The starting dose of Zyrtec for adults and children 6 years of age and older is 10 milligrams (mg) per day. This is enough to last 12 to 24 hours, depending on the person’s allergies. One pill is enough for daily relief, as it is effective longer than Benadryl.

Adults and children 12 years and older can take Benadryl in doses of 25 milligrams (one tablet) or 50 milligrams (two tablets). People 12 years and older may take one (25 milligrams) or two (50 milligrams) tablets, with a maximum of six tablets in 24 hours.

Can I Combine Other Allergy Medications?

Generally, you should avoid taking two medications from the same class simultaneously. However, in some cases, you might wonder whether you can go ahead and try another allergy medication if you're unsuccessful in managing your symptoms with another.

Still, this may not provide any extra relief. If you cannot treat your symptoms with one medication alone, it's best to work with a healthcare provider to target your treatment better.

Combining Other Medications With Zyrtec or Benadryl

You can take other allergy medications with Zyrtec or Benadryl if they belong to a different therapeutic class.

For example, you might try adding a decongestant or steroid nasal spray, such as Flonase (fluticasone propionate). These are safe to take if you have already taken an antihistamine.

However, studies have suggested that taking oral antihistamines with steroids does not necessarily provide any extra symptom relief compared to using a steroid alone.

It is always best to speak with your primary healthcare provider before starting another medication for the same use. More often than not, your healthcare provider may recommend switching your medication to another one before adding them together.

What Other OTC Drugs Are Available for Allergy Symptoms?

There are many other medications available for allergies that you can find at your local pharmacy or convenience store without a prescription.

Some examples of other antihistamines include:

• Claritin (loratadine)

• Clarinex (desloratadine)

• Allegra Allergy, Allegra Hives (fexofenadine)

Decongestants are another type of drug class commonly used for allergy symptoms. These can help relieve congestion. Examples include:

• Sudafed (pseudoephedrine)

• Sudafed PE (phenylephrine)

• Zicam Extreme Congestion, Afrin (oxymetazoline)

Steroids are also effective drugs for allergies. Examples of steroids include:

• Flonase Allergy Relief (fluticasone propionate nasal spray)

• Rhinocort Allergy (budesonide)

• Nasacort Allergy 24 Hour (triamcinolone)

Summary

Antihistamines, including Zyrtec and Benadryl, are a group of medications that can be used without a prescription to treat allergy symptoms.

It would be best if you did not double up on antihistamines, such as Zyrtec and Benadryl, simultaneously without getting a healthcare provider's OK. Taking them simultaneously will not make them more effective at reducing your allergies and can increase the risk of side effects.

If one of these medications is not working alone, you might need to try a different allergy medication or consult a healthcare provider for more targeted treatment.

Frequently Asked Questions

Can you take Zyrtec or Benadryl while pregnant?

Animal studies have not shown any harm from taking Zyrtec or Benadryl during pregnancy. However, no human studies have determined these medications to be safe to take while pregnant. While oral antihistamines are generally considered safe, there is no 100% certainty when it comes to pregnancy in humans.

If you are pregnant, ask your healthcare provider what options are most appropriate.

Can you overdose on Zyrtec and Benadryl?

You can overdose on any anti-allergy medication if you take too much or use multiple types of allergy medications simultaneously.

Symptoms of an overdose may include severe drying symptoms (e.g., dry eyes, dry mouth), constipation, and sedation. Other symptoms reported during overdoses have included rhabdomyolysis, seizures, and heart-related problems.

The author would like to recognize and thank Jaycob Mathew Peña for contributing to this article.