Can you take Zyrtec twice a day?

In this article:

• Can you take Zyrtec twice a day?
• Risks of exceeding the standard Zyrtec dosage
• Healthcare professional advice on handling severe allergies
• The bottom line

In this article

• Can you take Zyrtec twice a day?
• Risks of exceeding the standard Zyrtec dosage
• Healthcare professional advice on handling severe allergies
• The bottom line

Zyrtec is an over-the-counter (OTC) antihistamine that relieves hay fever or allergy symptoms, such as runny nose, sneezing, watery eyes, and itchy eyes. Zyrtec can be taken as a tablet, chewable tablet, orally disintegrating tablet, capsule, or syrup. It is available for adults and children and is taken once every 24 hours.

Can you take Zyrtec twice a day?

Taking Zyrtec more than once in 24 hours is not recommended without talking to a healthcare provider first. “I do not recommend higher doses without being examined by a physician and having appropriate evaluation and discussion about the medication,” says Dr. Tiffany Owens, MD, an allergist and immunologist at The Ohio State University Wexner Medical Center.

However, a healthcare provider or pharmacist may prescribe a two-a-day dosage for people with certain conditions. “Twice daily Zyrtec may be recommended for severe symptoms associated with hives and swelling under the skin,” adds Dr. Luke Hentrich, Pharm.D., BCPS, an assistant professor who answered the questions in conjunction with Hannah Suber, a Pharm.D. candidate, both at the University of Tennessee’s Health Science Center College of Pharmacy. 

According to a study in The Journal of Dermatological Treatment, a double dose of cetirizine hydrochloride, the active ingredient in Zyrtec, is effective for patients with urticaria (hives).

While higher doses of antihistamines may be recommended in some situations, Dr. Owens continues to explain it’s considered “off-label,” which means doing so isn’t FDA-approved.

“While taking Zyrtec twice daily is unlikely to cause harm, it may intensify side effects, such as drowsiness, dry mouth and eyes, constipation, headache, and insomnia,” Dr. Hentrich says. He agrees that talking to a healthcare provider or pharmacist beforehand is important.

Risks of exceeding the standard Zyrtec dosage

As an antihistamine, Zyrtec can cause common side effects, such as headache, sore throat, abdominal pain, tiredness, cough, and allergic reactions (though serious side effects are rare). The maximum dosage of Zyrtec for adults is 10 mg a day, and taking a higher dosage may strengthen or increase those side effects.

“In particular, high doses of antihistamine can cause increased sedation, dry mouth, or urinary retention,” Dr. Owens says. Dr. Hentrich adds an increased risk of fatigue, muscle weakness, sleepiness or sedation, dry eyes, excessive thirst, and more.

Even scarier, too much Zyrtec within a certain period can lead to an overdose. Dr. Hentrich says side effects from the overuse of antihistamines include delusions, agitation, and altered mental status, among other symptoms. Signs of antihistamine poisoning, which usually develop within six hours of overdose, include tachycardia (fast heart rate), dry mouth, blood pressure problems, agitation, psychosis, and more.

It’s important to note that some populations are at a higher risk of these side effects. Namely, patients with kidney or liver disease since their bodies may not be able to metabolize higher doses, according to Dr. Owens. Similarly, Dr. Hentrich says patients with impaired kidney or liver function may need lower doses of Zyrtec.

People who are breastfeeding may also want to be cautious. “Antihistamines can decrease breast milk supply; thus, I advise that breastfeeding be well-established before starting cetirizine in a breastfeeding person,” Dr. Owens recommends.

Additionally, when a breastfeeding parent takes Zyrtec, it can be transmitted to the baby through the milk—which isn’t without some concern. “Drowsiness and irritability have been reported in breastfed infants,” Dr. Hentrich says. “The risks and benefits should be considered in collaboration with your provider before breastfeeding in the setting of Zyrtec use.”

Healthcare professional advice on handling severe allergies

Severe allergies can cause serious issues, such as anaphylaxis, but certain allergens can be hard to avoid. “Non-pharmacologic treatment with allergen avoidance (i.e., pollen, pet dander) is encouraged, but not always practical,” Dr. Hentrich validates.

He says current treatment recommendations for allergies include intranasal corticosteroids (a type of steroid), oral antihistamines, and oral decongestants, including Zyrtec-D, that can be purchased over the counter. 

“These aid in most symptoms associated with allergic rhinitis, including congestion, runny nose, sneezing, and nasal itching,” he explains. “Of note, intranasal corticosteroids, such as Flonase, have shown the most benefit in treating persistent, year-round allergies.” This nasal spray can provide allergy relief by blocking the body’s production of histamines.

What if you take different allergy medicines? Can you double up then, and will doing so speed up the symptom-relief process? For example, can you safely take Zyrtec and Claritin 12 hours apart? 

In short, it depends. Generally, since these two medications are in the same class, it is not recommended to take them together in a 24-hour period. If you’re switching from one allergy medication to the other, wait 24 hours after a Zyrtec or 12 to 24 hours after a Claritin, depending on the dosage you consumed. 

If you’re looking for a more natural allergy treatment, vitamins and supplements such as vitamin C, apple cider vinegar, quercetin, and more may boost the immune system and reduce allergy-related inflammation—but the evidence supporting these options isn’t as straightforward. 

The bottom line

Taking Zyrtec twice in 24 hours is usually not recommended, though a healthcare provider may prescribe it for particular conditions.

Don’t make any new changes to the recommended dose without talking to a healthcare professional. “It is highly important that the patient’s medical history and healthcare concerns are carefully reviewed and that appropriate testing is done, when necessary,” Dr. Owens says. 

In this case, she adds that an allergist can review symptoms and formulate an individualized treatment plan in collaboration with the patient. They can look at each patient’s specific case and assess how to treat it without interfering with other medications or health conditions the patient might have. 

Dr. Hentrich gives an example. “It’s important to identify allergic rhinitis versus non-allergic rhinitis, as anti-allergy medications will not benefit all patients,” he says. “Always consult with your healthcare provider to aid in diagnosis and identification of symptoms to ultimately recommend appropriate treatment options.”

He adds that allergy treatments often have many side effects that can harm patients and may even have significant drug and disease interactions. “Patient-specific risks and benefits should be considered with the help of a physician or pharmacist before beginning medication treatment.”