Both Zyrtec and Claritin treat allergies. Zyrtec works faster and is stronger but more sedating, while Claritin is less drowsy. Ask a pharmacist which suits you.
Zyrtec (cetirizine)
- Works within about 1 hour.
- Lasts 24 hours.
- More likely to cause drowsiness (about 10% of people).
Claritin (loratadine)
- Takes 1 to 3 hours.
- Lasts 24 hours.
- Less drowsy.
Which is better
Studies suggest cetirizine is slightly more effective for some. Claritin suits daytime.
Both
OTC, once daily.
Check
Ask a pharmacist if you take other medicines.
How they work
Both are second generation antihistamines that block histamine H1 receptors and treat sneezing, runny nose, itchy eyes and hives. Neither is a decongestant.
Onset and duration
Zyrtec (cetirizine) starts working within about 1 hour, and Claritin (loratadine) in about 1 to 3 hours. Both last about 24 hours with a daily dose of 10 milligrams.
Drowsiness
Cetirizine is more likely to cause drowsiness, in about 10% to 14% of users, according to the label and studies. Loratadine is considered non-sedating, with rates similar to placebo (about 2% to 6%) at standard doses.
Effectiveness
Some studies suggest cetirizine works somewhat better for allergic rhinitis and hives, though individual response varies. A 2019 review in Annals of Allergy found that both are effective and that cetirizine may give faster relief.
Side effects
Dry mouth, headache, fatigue. Rare serious reactions.
Prescription and OTC
Both are available over the counter in the US, and in generic forms (cetirizine and loratadine) that cost much less than brand names.
Age
Cetirizine can be used in children aged 6 months and older with dosing by age; loratadine in children aged 2 and older. Check the label or ask a pediatrician.
Pregnancy and conditions
Both are commonly considered options in pregnancy, but ask your doctor. People with kidney or liver disease may need lower doses.
Alcohol and driving
Avoid alcohol with cetirizine, and don’t drive until you know how it affects you.
Pruritus after stopping
Severe itching after stopping long-term cetirizine has been reported, and the FDA added a warning in 2023.
Which to choose
If daytime alertness matters, loratadine or fexofenadine may be preferred. If symptoms are strong, cetirizine may be effective. A pharmacist can help.
Compare the two antihistamines
Cetirizine (Zyrtec) and loratadine (Claritin) are second generation antihistamines used for hay fever, hives and pet allergies. Cetirizine typically starts working within about 1 hour, and loratadine in 1 to 3 hours. Both last 24 hours. Cetirizine is somewhat more likely to cause drowsiness, reported in around 10 to 14 percent of users, versus about 8 percent with loratadine in trials.
Choosing
Some studies show cetirizine is slightly stronger for symptom relief. Choose by your response and side effects. Children’s formulations exist for each at set age limits. Check with a pharmacist if you are pregnant, take other medicines, or have liver or kidney disease. Avoid alcohol with cetirizine because it can increase drowsiness.
Based on data from the US Food and Drug Administration and the American Academy of Allergy, Asthma and Immunology
