Can I take Zyrtec and DayQuil together?

What is in Zyrtec and Zyrtec-D?

Both come from the same brand, but they are not the same pill. Here is what each DailyMed label lists:

The "D" means decongestant. That one letter is what changes the answer when you add DayQuil.

• Zyrtec Allergy tablet - cetirizine HCl 10 mg, an antihistamine. Adults and children 6 and over take 1 tablet once a day, no more than 1 in 24 hours.
• Zyrtec-D - cetirizine HCl 5 mg plus pseudoephedrine HCl 120 mg, a nasal decongestant, in an extended-release tablet. Adults and children 12 and over take 1 tablet every 12 hours, no more than 2 in 24 hours. Swallow it whole.

What is in DayQuil?

DayQuil is a family of products, not one formula. None of the 4 adult DayQuil products below lists an antihistamine on DailyMed, so none of them doubles the cetirizine in Zyrtec. The decongestant is where they differ:

DailyMed also lists some PE-free DayQuil Cold and Flu tablets with acetaminophen and dextromethorphan only, so the box in your hand is what counts.

• DayQuil Cold & Flu (liquid or LiquiCaps) - acetaminophen 325 mg, dextromethorphan 10 mg and phenylephrine 5 mg per 15 mL of liquid. The LiquiCaps list the same 3 ingredients. An adult liquid dose is 30 mL.
• DayQuil Severe Cold & Flu - the same 3, plus guaifenesin. Still has phenylephrine.
• DayQuil-D Cold & Sinus - acetaminophen, dextromethorphan, guaifenesin and pseudoephedrine 30 mg per LiquiCap, so 60 mg per 2-LiquiCap dose. This is the same decongestant as Zyrtec-D.
• DayQuil High Blood Pressure Cold & Flu - acetaminophen and dextromethorphan only. No decongestant and no antihistamine.

Why not Zyrtec-D with DayQuil?

Zyrtec-D gives you pseudoephedrine. DayQuil Cold & Flu and DayQuil Severe give you phenylephrine. They are different drugs, but both are nasal decongestants doing the same job. Taking both means 2 decongestants at once. DayQuil-D with Zyrtec-D is a direct double: 2 products with pseudoephedrine.

MedlinePlus says to check cough and cold labels carefully before using 2 or more products at the same time, because they may contain the same active ingredient and taking them together could cause an overdose. Both the Zyrtec-D and DayQuil Cold & Flu labels say to stop use and ask a doctor if you get nervous, dizzy or sleepless.

If you want allergy relief plus DayQuil, the simpler pairing is plain Zyrtec with one DayQuil product. If you need Zyrtec-D for congestion, ask a pharmacist which cold product fits without a second decongestant. DayQuil High Blood Pressure has no decongestant, but check its full label with the pharmacist too.

Will Zyrtec and DayQuil make me drowsy?

Cetirizine can. The Zyrtec and Zyrtec-D labels both say drowsiness may occur, to avoid alcoholic drinks, that alcohol, sedatives and tranquilizers may increase drowsiness, and to be careful when driving or using machinery. They also say to ask a doctor or pharmacist before use if you take tranquilizers or sedatives.

Notice how you feel on Zyrtec alone before you drive on the combination. If Zyrtec is new to you, the first day you add DayQuil is not the day to find out.

Alcohol matters for DayQuil too. The DayQuil label says severe liver damage may occur if an adult has 3 or more alcoholic drinks every day while using it, because it contains acetaminophen.

What should you not add on top?

Once you are on Zyrtec plus DayQuil, the overlaps to watch come from a third product. These come from the labels:

• Tylenol or any other acetaminophen - every DayQuil product above contains acetaminophen, and the DayQuil labels say not to use it with any other drug that contains acetaminophen.
• NyQuil while you are on Zyrtec - NyQuil Cold & Flu contains doxylamine, which its label lists as an antihistamine, plus acetaminophen and dextromethorphan. That stacks 2 antihistamines, and the NyQuil label says marked drowsiness may occur.
• Another allergy pill - Zyrtec is already your antihistamine for the day. Do not add a second one.
• Sudafed or another decongestant - MedlinePlus lists Sudafed Congestion and Sudafed 12/24 Hour as pseudoephedrine. If your DayQuil or Zyrtec-D already has a decongestant, another product with one adds more of the same.
• Advil or Motrin (ibuprofen) - neither Zyrtec nor DayQuil lists ibuprofen. That question is covered on our DayQuil and ibuprofen page.

Who should ask a pharmacist first?

Even with plain Zyrtec and no overlap, these label warnings still apply:

• You take an MAOI (certain antidepressants, psychiatric or Parkinson's drugs), or stopped one in the last 2 weeks. DayQuil and Zyrtec-D both say do not use.
• High blood pressure, heart disease, thyroid disease, diabetes, or trouble urinating from an enlarged prostate - the DayQuil Cold & Flu and Zyrtec-D labels say ask a doctor before use. Zyrtec-D also lists glaucoma.
• Liver or kidney disease - the Zyrtec label says ask a doctor, who should decide if you need a different dose. The DayQuil label also lists liver disease.
• You take warfarin - ask a doctor or pharmacist before DayQuil, per its label.
• You are 65 or older - the Zyrtec and Zyrtec-D labels say ask a doctor.
• Pregnant or breastfeeding - the Zyrtec labels say ask a health professional if pregnant and say breastfeeding use is not recommended. The DayQuil labels say ask a health professional before use.
• Children - the Zyrtec-D label gives directions for ages 12 and up and says ask a doctor under 12. The Zyrtec label gives directions for ages 6 and up and says ask a doctor under 6. For a child, ask a pharmacist or pediatrician before combining anything.