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Cetirizine vs. Loratadine: What's the Difference?

Edited by Harlon Moss || By Janet White || Published on January 17, 2024
Cetirizine is an antihistamine used for allergy relief, known for its faster onset but can cause drowsiness. Loratadine is another antihistamine for allergies, less likely to cause drowsiness, slower onset.

Key Differences

Cetirizine is an antihistamine known for its quick onset of action, usually within an hour, making it effective for rapid relief of allergy symptoms. Loratadine, while also an antihistamine, typically takes longer to take effect, often requiring one to three hours.
One of the notable differences is that cetirizine is more likely to cause drowsiness compared to loratadine, which is less sedating and thus preferred for those who need to avoid drowsiness.
Cetirizine is often recommended for acute allergic reactions due to its faster action. In contrast, loratadine is favored for long-term allergy management because of its longer-lasting effects and minimal impact on alertness.
When it comes to treating more severe allergic symptoms, like hives, cetirizine is generally considered more effective. However, loratadine is often chosen for routine allergy prevention due to its lower risk of sedation.
In terms of metabolism, cetirizine is metabolized to a lesser extent in the liver, making it a suitable option for patients with liver impairment. Loratadine undergoes more extensive liver metabolism, requiring caution in patients with liver conditions.

Comparison Chart

Onset of Action

Fast (within 1 hour)
Slower (1-3 hours)

Sedation Risk



More effective for severe reactions
Preferred for routine allergy management

Duration of Effect


Liver Metabolism

Less extensive
More extensive

Cetirizine and Loratadine Definitions


An antihistamine used for treating allergies and hay fever.
She took cetirizine to quickly relieve her pollen allergies.


An antihistamine used for long-term allergy symptoms management.
Loratadine is part of his daily routine during allergy season.


A medication effective for relieving itching and swelling caused by hives.
Cetirizine helped reduce the itching from his hives.


Less likely to cause drowsiness, making it suitable for daytime use.
She prefers loratadine to avoid drowsiness at work.


Can cause drowsiness, thus should be used cautiously when operating machinery.
After taking cetirizine, he avoided driving due to drowsiness.


Undergoes more extensive metabolism in the liver.
Due to its metabolism, loratadine dosage might be adjusted in liver impairment.


Requires less liver metabolism, making it a choice for patients with liver issues.
Her doctor recommended cetirizine due to her liver condition.


Effective in treating symptoms like sneezing, runny nose, and eye irritation.
Loratadine relieved her sneezing and runny nose.


Known to provide faster allergy symptom relief compared to some antihistamines.
Cetirizine's fast action is ideal for sudden allergic reactions.


Has a longer duration of effect, often lasting 24 hours.
A single dose of loratadine keeps her allergy-free all day.


A nonsedating antihistamine, C21H25ClN2O3, used in the form of its hydrochloride to treat allergic rhinitis and other allergic disorders.


A nonsedating antihistamine, C22H23ClN2O2, used to treat allergic rhinitis and other allergic disorders.


(pharmaceutical drug) A major metabolite of hydroxyzine, an antihistamine used in the treatment of allergies, hay fever, angioedema, and urticaria.


(pharmacology) An antihistamine drug used to treat allergies.


How quickly does cetirizine work?

Usually within an hour of ingestion.

What is cetirizine used for?

Treating allergies and hay fever symptoms.

Can loratadine cause drowsiness?

It's less likely to cause drowsiness compared to cetirizine.

Can cetirizine be taken at night?

Yes, especially since it may cause drowsiness.

Is cetirizine suitable for severe allergies?

Yes, especially for acute reactions like hives.

How long does loratadine's effect last?

About 24 hours.

Can children take cetirizine?

Yes, in doses appropriate for their age.

What is loratadine used for?

Long-term management of allergy symptoms.

Is loratadine safe for liver patients?

It requires more liver metabolism, so use with caution.

What are the side effects of cetirizine?

Drowsiness, dry mouth, and sometimes nausea.

Can cetirizine be taken with other medications?

Consult a doctor as it can interact with certain drugs.

What are the side effects of loratadine?

Dry mouth, headache, and in rare cases, drowsiness.

Can I drink alcohol with loratadine?

Alcohol may increase the sedative effect, so it's best to avoid.

Is cetirizine a prescription drug?

It's available both over-the-counter and by prescription.

Is loratadine effective for skin allergies?

Yes, it can help relieve skin allergy symptoms.

Is loratadine better for daytime allergy relief?

Yes, due to its minimal sedative effects.

Can loratadine be used for pet allergies?

Yes, it's effective for pet dander allergies.

How often should cetirizine be taken?

Typically once a day, or as prescribed.

Can pregnant women take loratadine?

It should be taken under medical supervision during pregnancy.

Does cetirizine increase blood pressure?

Not commonly, but consult a doctor if you have hypertension.
About Author
Written by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.

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