Important Shipping Update – Please Read. More info

Can you take zyrtec and benadryl together?

Benadryl (diphenhydramine) and Zyrtec (cetirizine) are both OTC antihistamines for allergy symptoms like sneezing, runny nose, itching, and watery eyes. Benadryl is short-acting (dosed every 4–6 hours), while Zyrtec lasts 24 hours per dose.

These two should not be taken together unless advised by a healthcare professional, as combining increases risk of side effects.

Are Zyrtec and Benadryl the same?

Both block histamine (allergy mediator) but differ:

  • Benadryl is a first-generation antihistamine (diphenhydramine). It crosses into the brain causing sedation. Forms: pills, creams, gels, sprays. Uses: allergies, bug-bite itching, motion sickness, sleep aid. Side effects: drowsiness, dry mouth, constipation, dizziness, nausea.
  • Zyrtec is a second-generation antihistamine (cetirizine). It minimally crosses into the brain, causing less sedation. Forms: tablets, liquid gels, chewables, dissolvables, liquid, nasal spray, Zyrtec‑D. Side effects: headache, dry mouth, blurred vision, constipation, nausea, sore throat, occasional drowsiness.

Can taking them together cause side effects?

Combining multiple oral antihistamines (Claritin, Allegra, Zyrtec, Benadryl, Clarinex) can lead to overdose symptoms: irregular heartbeat, extreme dry mouth/eyes, agitation, seizures, loss of coordination. Seek immediate help via Poison Control (1-800-222-1222) or 911 for severe symptoms.

Safe combinations of allergy medications

You can safely combine medications that work differently, for example:

  • Oral antihistamine (Claritin, Allegra, Zyrtec) with a steroid nasal spray (Rhinocort, Flonase)
  • Oral antihistamine plus a decongestant nasal spray or oral decongestant if needed
  • Zyrtec‑D (cetirizine/pseudoephedrine) for congestion, unless you have high blood pressure or heart disease

Timing between Zyrtec and Benadryl

Zyrtec lasts up to 24 hours. Wait at least 24 hours after Zyrtec before taking another antihistamine. Benadryl lasts 4–6 hours; wait at least 6 hours after Benadryl before taking another antihistamine.

Non-medication allergy management

  • Identify and avoid allergens (pollen, dust mites, pet dander, mold, smoke)
  • Use saline nasal rinses or sprays
  • Shower and change clothes after outdoor exposure
  • Clean and vacuum with HEPA filters
  • Wash bedding in hot water every 2 weeks
  • Elevate the head of your bed 30–45° to reduce nighttime symptoms

What not to mix with Zyrtec

  • Alcohol
  • Other oral antihistamines (Benadryl, Claritin, Allegra)
  • Opioids (oxycodone)
  • Sleep medications (zolpidem)
  • Other sedating drugs (muscle relaxers, seizure meds, antidepressants, antipsychotics, antianxiety meds)

Sources

  • Naqvi A, Patel P, Gerriets V. Cetirizine. StatPearls. Updated May 6, 2024. Accessed Apr 29, 2025.
  • Zyrtec (cetirizine hydrochloride) Tablets and Syrup For Oral Use. Pfizer. Last updated 5/2019. Accessed Apr 29, 2025.