Key takeaways
The standard Zyrtec dosage for adults and children aged 6 years or older is 5 mg or 10 mg, taken once daily. Children ages 2 to 5 can take 2.5 mg once daily.
The maximum dose of Zyrtec in adults and children ages 6 and older is 10 mg every 24 hours.
Taking too much Zyrtec increases the risk of side effects such as drowsiness and dry mouth, and increases the risk of antihistamine poisoning. Call poison control or seek urgent medical attention if you suspect an overdose.
Zyrtec (generic name cetirizine) is an over-the-counter medication used to relieve allergy and hay fever symptoms, such as runny nose, sneezing, and watery eyes. This second-generation antihistamine is available in several forms for adults and children: tablets, liquid gels, oral syrup, chewable tablets, and oral disintegrating tablets. We’ll explain how much Zyrtec you can take, Zyrtec dosing by age and formulation, the maximum safe dosage, what happens if you take too much Zyrtec, and when to see your healthcare provider.
Zyrtec (cetirizine) dosage at a glance |
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|---|---|---|---|
| Age group | Dose | How often | Max per day |
| Adults and children ages 6 years and older | 5 or 10 mg | Once daily | 10 mg |
| Children ages 2 to 5 years old | 2.5 mg | Once daily | 5 mg |
| Children under 2 years old | Consult a healthcare provider | — | — |
Zyrtec dosage for adults
The standard adult dose for Zyrtec (or generic cetirizine) is 5–10 mg once daily, according to the National Institutes of Health. The maximum dose is 10 mg per 24 hours.
Adults who want quick relief might be tempted to reach for the maximum Zyrtec dose, 10 mg. But for some people, a 5 mg dose adequately relieves allergy symptoms with fewer side effects (namely, drowsiness). The drug label uses “symptom-based language,” meaning that you should take into consideration the severity of allergy symptoms when choosing between a 5 mg or 10 mg dose, according to Kara Wada, MD, FAAAAI, a board-certified allergist and immunologist in central Ohio.
Some adults may also require a lower dose because of underlying kidney or liver conditions. “The kidneys are the primary way the body eliminates cetirizine,” Dr. Wada says. If you have kidney issues, the medication can accumulate, especially if another dose is taken the next day.
The same goes for people with liver problems. “Instead of getting about a day’s worth of effect from a dose, some people may notice the medication seems to last longer, and they may be more likely to experience side effects,” says Chrissie Ott, MD, a double board-certified internist and pediatrician in Portland, Oregon. A healthcare professional can determine if reduced kidney function or liver impairment makes Zyrtec unsafe or whether a lower dose of 5 mg per day may be required.
For questions or concerns about safe Zyrtec dosage for adults, consult a licensed healthcare provider.
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Zyrtec dosage for children
Children 6 years and older can also take up to 10 mg Zyrtec per day. Per the drug label, the standard pediatric dose for children 2 to under 6 years of age is 2.5 mg once daily. That said, the dose can be increased to a maximum of 5 mg per day if necessary, administered as either a single 5 mg dose or two 2.5 mg doses given every 12 hours.
“The decision [between 2.5 mg or 5 mg] isn’t based on whether the child is 2, 3, 4, or 5 years old. It’s based on how well the symptoms are controlled,” Dr. Ott says. “The goal is always the lowest effective dose: enough to control symptoms without causing unnecessary sleepiness or other side effects.”
Zyrtec is not recommended for children under 2 years old without a healthcare provider’s guidance. In some cases, a healthcare professional familiar with the child’s condition and health history may suggest it. Seek personalized medical advice for any questions about Zyrtec for young children.
Children’s Zyrtec, like other medications, should be kept out of reach of children. Because Children’s Zyrtec tablets and oral solution are flavored to make them more palatable for children, they present a risk of accidental ingestion if the medicine is stored out in the open or in a place where the child can find it.
Can you take Zyrtec twice a day?
In general, no, you shouldn’t take Zyrtec twice a day. Zyrtec is intended to be a once-daily medication, and 10 mg is the maximum dose per day.
That said, some situations warrant taking Zyrtec twice a day, provided it is done under the recommendation and guidance of a healthcare provider:
- Two 2.5 mg doses for children: If a child aged 2 to under 6 first takes a 2.5 mg dose that does not sufficiently suppress hay fever symptoms, the medication label states that a second 2.5 mg dose can be administered, for a maximum total of 5 mg taken in a 24-hour window.
- Severe symptoms of certain conditions: One study published in The Journal of Dermatological Treatment found that double doses of cetirizine hydrochloride (the active ingredient in Zyrtec) could effectively treat patients with hives (urticaria). Still, this should only be done if recommended by a healthcare provider.
Taking more than the recommended Zyrtec dose can increase the risk of side effects, including serious side effects such as seizures or changes in blood pressure or heart rhythm.
What happens if you take too much Zyrtec?
Taking too much Zyrtec can cause Zyrtec overdose symptoms, including extreme drowsiness, hallucinations, rapid heartbeat, or, especially in children, agitation. People at the greatest risk of symptoms from Zyrtec overdose are children, older adults, and anyone with kidney or liver problems.
In most cases, accidental cetirizine overdose is not life-threatening. But since taking too much can cause dangerous psychiatric or neurological symptoms, it’s important to treat any double-dosing or overdose as a medical emergency. Contact Poison Control (1-800-222-1222 in the U.S.) or seek urgent medical care if an overdose is suspected.
Zyrtec side effects and safety considerations
Even safe doses of Zyrtec can cause side effects, such as drowsiness, fatigue, and dry mouth, according to MedlinePlus. Older adults may be more likely to experience sleepiness and fatigue with Zyrtec, so take extra precautions to prevent falls.
The good news is that second-generation antihistamines such as Zyrtec and Claritin are less likely to cause drowsiness than first-generation antihistamines such as Benadryl. Drowsiness can also vary depending on the person’s sensitivity to the medication. Until you know how Zyrtec affects you, avoid driving or operating heavy machinery.
Zyrtec isn’t right for everyone. As mentioned above, anyone with kidney or liver problems should consult a healthcare professional before taking Zyrtec. It’s also important to consult a healthcare provider before taking this medication while pregnant or breastfeeding.
Finally, don’t take Zyrtec with another second-generation antihistamine such as Claritin (loratadine) or Allegra (fexofenadine). Also don’t take it with other sedating medications or alcohol, since the combination can cause extreme sleepiness and make it harder to think clearly.
How much does Zyrtec cost?
Over-the-counter Zyrtec prices vary by pharmacy and location, but you can typically get a much lower price by purchasing generic cetirizine tablets. The average retail price of cetirizine (generic Zyrtec) is $23 for 30 10 mg tablets, but at participating pharmacies, a SingleCare coupon or discount card can lower the price to $9 for 30 10 mg tablets.
It’s true that Zyrtec is widely available over the counter. However, asking your provider to write a Zyrtec prescription can help you save if your insurance plan covers it. You can also use a SingleCare discount card or a free coupon for prescription medications.
Expert takeaway
“Although Zyrtec is typically labeled as a non-drowsy medication, it still commonly causes drowsiness,” says Ashley Wong, Pharm.D., member of the SingleCare Medical Review Board. “However, it is less sedating than other antihistamines, such as Benadryl and doxylamine.”
Frequently asked questions
Can you take 20 mg of Zyrtec in a day?
No, the maximum Zyrtec dose is 10 mg per 24 hours. Taking 20 mg of Zyrtec in a day is not safe, as it can increase your risk of side effects.
Can I take Zytec morning and night?
No, you shouldn’t take Zyrtec more than once every 24 hours. The maximum adult dose is 10 mg once daily.
Does Zyrtec work better on an empty stomach?
Zyrtec doesn’t necessarily work better on an empty stomach, but it may work more quickly. According to the National Institutes of Health, cetirizine (the active ingredient in Zyrtec) may take slightly longer to work when taken with food compared to taking it on an empty stomach.
The SingleCare prices in this article are the most accurate at the time of publishing in ZIP code 23666 as of Jul. 14, 2026. Prices vary by pharmacy. Visit our coupon page for updated drug prices at pharmacies near you.
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