Cetirizine (Zyrtec) Pediatric Dose Calculator
Label dose by age: 2.5 mg once daily at 2 to 5 years (up to 5 mg a day) and 5 or 10 mg once daily from 6 years; under 2 years only if a doctor directs. The calculator gives a weight-based estimate in mL; check it against the age dose.
Children's Zyrtec dose
Need children's Zyrtec dose help by age or form?
Cetirizine is the generic version of Zyrtec. Most families landing here want children's Zyrtec dosing, a quick chart by age or product form, or help moving from the bottle in the house to a clear once-daily allergy plan.
Zyrtec dosing chart
See the label age chart for Children's Zyrtec liquid and chewable tablets.
Liquid, chewable, and tablet guide
Review practical tips for choosing the right form and giving once-daily cetirizine consistently.
Compare common antihistamines
Use the antihistamine hub to see where cetirizine fits among common allergy medicines.
Compare with loratadine (Claritin)
Open loratadine when the family wants another once-daily, lower-drowsiness option.
Compare with fexofenadine (Allegra)
Open fexofenadine when low sleepiness risk and juice/antacid timing are part of the choice.
Compare with levocetirizine (Xyzal)
Open levocetirizine when the question is a closely related daily antihistamine option.
label dose by age
How the cetirizine dose is worked out
The FDA label sets the cetirizine dose by age, not weight. The calculator has no age field: it gives a weight-based estimate, and its caps use weight bands that stand in for age (about 12 kg for 2 years, 20 kg for 6 years). A child who is heavy for their age can get more than the label dose for their age, so always use the age dose.
Formula
Calculator: mL per dose = (weight in kg × mg/kg/day ÷ doses per day), capped by weight band, ÷ strength in mg per mL. Use the label dose for the child's age when it differs.
Worked example
A 3-year-old weighing 14 kg at 0.25 mg/kg/day: the calculator estimates 3.5 mg; the label dose for 2 to 5 years is 2.5 mg once daily, up to 5 mg a day. A 4-year-old weighing 22 kg at 0.5 mg/kg/day: the calculator gives 10 mg, twice the 5 mg daily maximum for 2 to 5 years. Use the age dose.
Safety checks before using the result
- Check the strength on the bottle: drops sold outside the US are often 10 mg/mL, 10 times stronger.
- Do not combine with other antihistamines unless a clinician directs it.
- Get emergency care for swelling of the face, lips or tongue, or trouble breathing.
Practical dosing guide
Before you measure the dose
Use this page to choose the cetirizine form that fits the child in front of you and confirm the once-daily plan before giving it.
- 5 mg/5 mL liquid
- US liquid is 1 mg/mL, so the mg dose equals the mL dose: 2.5 mg is 2.5 mL, 5 mg is 5 mL, 10 mg is 10 mL.
- Chewable
- The 10 mg Children's Zyrtec chewable is labeled for 6 years and older; chew or crush it completely before swallowing.
- Tablet
- Tablets are often the cleanest once-daily option for older children and teens who can swallow pills without trouble.
Cetirizine pediatric medication summary
Cetirizine (Zyrtec) pediatric dose by age from the FDA label: 2.5 mg once daily from 6 months (prescriber-directed under 2 years), up to 5 mg a day at 2 to 5 years, and 5 or 10 mg once daily from 6 years, with mL for 1 mg/mL liquid.
Dose by age: 2.5 mg once daily from 6 months; up to 5 mg a day at 2 to 5 years; 5 or 10 mg once daily from 6 years (max 10 mg in 24 hours).
US liquid is 1 mg/mL (5 mg/5 mL), so each mg is 1 mL. Drops sold outside the US are 10 mg/mL, 10 times stronger.
Cetirizine indications and common pediatric uses
Cetirizine is labeled in the US for allergic rhinitis and chronic hives in children. This section lists what the labels cover and where guidelines place it.
Allergic rhinitis (hay fever and year-round allergies)
Allergic rhinitis (hay fever and year-round allergies): Give once daily at the same time each day.
Chronic hives (chronic idiopathic urticaria)
Chronic hives (chronic idiopathic urticaria): Hives that last more than 6 weeks are called chronic urticaria; see a clinician.
How to give Cetirizine
- How to measure and give cetirizine to children safely.
- Use the dosing cup that comes with the product, or an oral syringe from the pharmacy. Check the strength on the bottle before every first dose: US liquid is 1 mg/mL, so the mg dose equals the mL dose.
- Give it at the same time each day. If your child is sleepy after a dose, ask your clinician whether evening dosing would suit them better.
Cetirizine side effects, contraindications, and interactions
Cetirizine is generally well tolerated. The most common side effects in children's trials were headache, sore throat, stomach ache and sleepiness.
Common side effects
- Sleepiness was more common at 10 mg (4.2%) than at 5 mg (1.9%) or placebo (1.3%) in children 6 to 11 years (label).
- Avoid alcohol, sedatives and other antihistamines, which add to drowsiness.
- Rarely, strong itching can start within a few days of stopping after long-term use; restarting or tapering may help.
Safety checks
- Swelling of the face, lips or tongue, or trouble breathing after a dose: Possible allergic reaction.
Drug interactions
- Review the full medication list with a clinician or pharmacist before combining therapies.
Cetirizine mechanism and clinical pearls
Cetirizine blocks histamine H1 receptors, which reduces sneezing, runny nose, itching and hives.
The US label sets the cetirizine dose by age, not weight. Convert mg to mL with the bottle strength (US liquid is 1 mg/mL).
US liquid is 1 mg/mL. Drops sold outside the US are 10 mg/mL, 10 times stronger.
Rarely, strong itching starts within a few days of stopping after months or years of daily use. Restarting or tapering may help (2025 label warning).
The international urticaria guideline recommends a second-generation antihistamine such as cetirizine as first-line treatment for hives, including in children.
Frequently asked questions about Cetirizine
It depends on age. 2 to 5 years: 2.5 mg (2.5 mL of 1 mg/mL liquid) once daily, which can go up to 5 mg a day, given as 5 mg once or 2.5 mg every 12 hours. 6 years and older: 5 or 10 mg once daily, no more than 10 mg in 24 hours. 6 to 23 months: 2.5 mg once daily, only if a doctor directs; 12 to 23 months may go to 2.5 mg every 12 hours.
No. The US label doses cetirizine by age. The calculator above works from weight and caps the result, so check it against the age dose. For context, in the label's trials most children aged 2 to 5 years received 0.2 to 0.4 mg/kg. If your child is much smaller or larger than others their age, ask your pediatrician or pharmacist.
Yes. Zyrtec is a brand of cetirizine. Store brands contain the same medicine, but check the strength on the bottle.
US cetirizine liquid is 1 mg/mL (5 mg/5 mL), so the dose in mg equals the dose in mL: 2.5 mg is 2.5 mL and 5 mg is 5 mL. Drops sold outside the US are often 10 mg/mL, which is 10 times stronger, so the volume is much smaller.
Only if a doctor directs it. OTC labels say to ask a doctor under 2 years. The prescription label covers 2.5 mg once daily from 6 months only for year-round (perennial) allergic rhinitis (6 to 23 months) and chronic hives (6 months to 5 years), not seasonal hay fever. It is not established under 6 months.
From 12 months to 5 years, the label allows 2.5 mg every 12 hours (5 mg a day in total). From 6 years the label dose is once daily. Under 12 months it is once daily only.
Some children feel drowsy. In the label's trials in children 6 to 11 years, sleepiness was reported in 1.9% at 5 mg and 4.2% at 10 mg, compared with 1.3% on placebo. Avoid other sedating medicines and alcohol.
Not as a routine treatment. Dermatology guidelines do not recommend non-sedating antihistamines like cetirizine for eczema (atopic dermatitis) unless the child also has hives or hay fever. Moisturizers and the treatments your clinician prescribes for the skin come first.
Rarely, strong itching can start within a few days of stopping after months or years of daily use. The 2025 label warning says symptoms may improve by restarting or tapering cetirizine. Talk to your clinician.
Do not combine it with other antihistamines (such as diphenhydramine, hydroxyzine or levocetirizine) unless a clinician says to. Check cough and cold products for antihistamines too.
Sources reviewed for Cetirizine
Children's Cetirizine Hydrochloride Oral Solution – Drug Facts
DailyMed (U.S. National Library of Medicine)
SourceCetirizine Hydrochloride Oral Solution, USP (Rx) – prescribing information
DailyMed (U.S. National Library of Medicine)
SourceDykewicz MS, et al. Rhinitis 2020: A practice parameter update. J Allergy Clin Immunol. 2020;146(4):721-767.
Journal of Allergy and Clinical Immunology
SourceZuberbier T, et al. The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticaria. Allergy. 2022;77(3):734-766.
Allergy (Wiley)
SourceChildren's Zyrtec (cetirizine HCl) syrup – Drug Facts
DailyMed (U.S. National Library of Medicine)
SourceChildren's Zyrtec Chewable Tablets 10 mg – Drug Facts
DailyMed (U.S. National Library of Medicine)
Source