Zyrtec-D XR Side Effects: What to Expect and When to Call Your Doctor

Zyrtec-D XR combines two active ingredients — cetirizine (an antihistamine) and pseudoephedrine (a nasal decongestant) — and like any combination product, it comes with a range of potential side effects. Most are mild and manageable, but some warrant a call to your doctor. Here's what you need to know before taking Zyrtec-D XR.

Common Side Effects of Zyrtec-D XR

In clinical trials of cetirizine/pseudoephedrine extended-release tablets, the most frequently reported side effects included:

Drowsiness or sleepiness — cetirizine causes sedation in some patients, though less than first-generation antihistamines like Benadryl

Dry mouth — both cetirizine and pseudoephedrine can reduce saliva production

Insomnia or difficulty sleeping — pseudoephedrine's stimulant properties can interfere with sleep, especially when taken in the evening

Nervousness or restlessness — sympathomimetic effect of pseudoephedrine

Headache

Dizziness

Nausea — mild gastrointestinal upset in some patients

Fatigue — particularly with cetirizine component

These common side effects are usually mild and often decrease as your body adjusts to the medication. They do not typically require stopping the medication, but let your pharmacist know if they persist or become bothersome.

Serious Side Effects: Call Your Doctor

Stop taking Zyrtec-D XR and seek medical attention if you experience any of the following:

High blood pressure (hypertension): Pseudoephedrine can raise blood pressure significantly. If you have a home blood pressure cuff, monitor your readings. Symptoms of severely elevated BP include severe headache, blurred vision, chest pain, or shortness of breath

Fast or irregular heartbeat (palpitations/arrhythmia): Pseudoephedrine stimulates adrenergic receptors in the heart, which can cause palpitations or tachycardia in some patients

Severe allergic reaction: Hives, swelling of face/lips/tongue/throat, difficulty breathing — call 911 immediately

Seizures: Rare but possible, especially in patients with pre-existing seizure disorders or those who have taken excessive doses

Difficulty urinating: Pseudoephedrine can worsen urinary retention, particularly in men with enlarged prostate (BPH)

Severe itching after stopping: The FDA warns that rarely, patients who have taken cetirizine for months to years may experience severe itching when they stop. Talk to your doctor before discontinuing long-term use

Side Effect Spotlight: Drowsiness vs. Insomnia

One of the unusual aspects of Zyrtec-D XR is that it contains a medication that can cause drowsiness (cetirizine) and a stimulant that can cause wakefulness (pseudoephedrine). Different patients experience these effects differently. Some feel drowsy despite the stimulant component; others feel too wired to sleep. If you're taking Zyrtec-D XR for the first time, take it in the morning (at least your first dose) to assess how you respond before taking it at night.

Who Is Most at Risk for Side Effects?

Patients with high blood pressure (monitor BP carefully; consider a decongestant-free alternative)

Men with benign prostatic hyperplasia (BPH) — risk of urinary retention

Patients with narrow-angle glaucoma — contraindicated

Elderly patients — increased sensitivity to sedation and cardiovascular effects

Patients taking MAO inhibitors — absolute contraindication; risk of hypertensive crisis

Tips to Reduce Side Effects

Take your morning dose with breakfast and avoid alcohol

Avoid taking the evening dose within 4 hours of bedtime (pseudoephedrine stimulant effect)

Stay well hydrated to counteract dry mouth and decongestant effects

Don't exceed 2 tablets per 24 hours

Do not combine with other antihistamines or decongestants

For more on medication safety, see our guide to

Zyrtec-D XR drug interactions.