Over-the-counter allergy relief medications Claritin (Loratadine) and Zyrtec (Cetirizine) have similar effects, but their ingredients are different, which means different groups of people will have rare but adverse reactions to them.
In general, both drugs are very safe and widely used. But people using muscle relaxants, sleeping pills, or other allergy medications should speak to a doctor before taking Zyrtec, while those suffering from liver disorders or phenylketonuria (PKU) should be careful with Claritin.
Both Claritin and Zyrtec are used to treat allergy symptoms caused by hay fever, hives, angioedema, and skin allergies. They should reduce general allergy symptoms, such as sneezing, a runny nose, and eye irritation, that are common with allergic reactions to environmental factors or foods. In some cases, Claritin and Zyrtec may be prescribed to treat mild to moderate headaches.
Efficacy of Zyrtec vs Claritin
In studies, Claritin and Zyrtec have provided much greater allergy relief than placebo, usually with few side effects. The two drugs have also, at times, outperformed similar allergy relief drugs or worked well alongside other drugs. It is worth noting that advertising seems to affect a person's perception of drug effectiveness.
Studies on Claritin
- Prophylactic (preventative) therapy with Claritin has been found to reduce or eliminate seasonal allergies.
- Symptoms associated with nonallergic rhinitis—a syndrome that results in allergy-like symptoms even though there is no known allergy—improved with the use of Claritin and Flunisolide.
- Claritin-D is Claritin with pseudoephedrine that comes in 12-hour and 24-hour doses. Both forms were highly effective at reducing allergy symptoms in patients, but 24-hour Claritin-D was much less likely to cause insomnia.
Studies on Zyrtec
- Zyrtec has been found to have positive, long-lasting effects compared to Allegra, with allergy symptoms still suppressed to varying degrees for up to 24 hours after initial dose. Zyrtec was also better at treating a runny nose, sneezing, eye irritation, and itchy throats.
- In a large study of over 800 adolescents between the ages of 12 and 15, a 30-day treatment with Zyrtec was found to severely reduce allergy symptoms. Moreover, the drug was found to be very safe.
- In one study, Zyrtec was found to be equally as effective as competing allergy relief drugs and superior to Claritin when it came to seasonal allergy relief. Zyrtec was also found to help with allergic cough and reactions to mosquito bites, though some further study is required to understand its effectiveness on those.
Forms and Appearance
Claritin is available in solid tablets, liquid syrup, and quick-dissolving tablets. Likewise, Zyrtec is available in both non-chewable and chewable forms, as well as in liquid syrup.
|Age Group||Claritin (Loratadine)||Zyrtec (Cetirizine)|
|Adults & Children (>6yrs)||1 10 mg tablet/reditab, or 2 tbs (10 mg) of syrup once daily.||5 mg or 10 mg once daily|
|Children (2 to 5 yrs)||1 tsp (5 mg)once daily.||2.5 mg (½ teaspoon) syrup once daily. Max dose is 5 mg per day.|
|Children (6 mo to <2yrs)||Not recommended||2.5 mg (½ teaspoon) once daily. For children 12-23 mo, max dose is 5 mg per day.|
|Adults & Children (>11yrs) with special condition (liver failure, renal or hepatic impairment)||Start with 1 tablet or 2 tsp (10 mg) every other day.||5 mg once daily.|
|Children (6-11yrs) with special condition (liver failure, renal or hepatic impairment)||Start with 1 tablet or 2 tsp (10 mg) every other day.||Not recommended|
Claritin and Zyrtec can also be used for dogs that suffer from a variety of allergic reactions or symptoms. Contact a veterinarian for appropriate dosage instructions for pets.
The cost of Claritin and Zyrtec varies depending on form; generic versions of both drugs are cheaper than the branded forms.
Claritin costs about $0.45 per tablet, or $17.98, for a pack of 30 tablets on Amazon.
Zyrtec costs less per tablet, overall. A pack of 70 on Amazon.com costs $23.99, or $0.34 per tablet.
While both Claritin and Zyrtec have relatively few side effects, some individuals may have a reaction to the drugs—usually a mild side effect that will not require contacting a doctor. For those taking other medication, including other allergy relief drugs, speaking to a doctor before taking Claritin or Zyrtec, too, is advisable.
A new side effect to these drugs may also be reported to US FDA at 1-800-FDA-1088 and Health Canada at 1-866-234-2345.
Common Side Effects
Claritin's most possible common side effects, which are typically not serious, include headache, feeling tired or drowsy, dry mouth, nervousness, stomach pain, diarrhea, eye redness, nosebleed, skin rash, and sore throat.
Zyrtec's common, less serious side effects can include drowsiness, dry mouth, sore throat, dizziness, headache, cough, nausea, or constipation.
Serious Side Effects
Serious side effects are rare for both Claritin and Zyrtec, but they can happen. In the event of experiencing one of the side effects below, patients are advised to contact their doctor immediately.
For Claritin, serious side effects can include fast or irregular heartbeats, feeling faint, yellowing of skin or eyes (signs of jaundice), urinary retention, and seizures.
Zyrtec's serious side effects may include a fast and heavy or irregular heart rate, extreme restlessness, uncontrollable shaking, sleep problems like insomnia, urinary retention, vision problems, and confusion.
Allergic reactions to Claritin or Zyrtec are very rare, thus their over-the-counter status. An allergic reaction to either of these drugs may include hives, difficulty breathing, and swelling of the face, lips, tongue, or throat. Those experiencing allergic reactions to Claritin, Zyrtec, or any other drugs should contact emergency care immediately.
Potential Link to Obesity
At least one correlative study has found a potential link between antihistamine drugs, like Claritin and Zyrtec, and obesity. Antihistamine drugs may affect some patients' normal appetite suppression neurotransmitters, thus leading patients to feel hungrier—and therefore eat more—than they would if they were not using an antihistamine. Further study is needed, but those concerned about their weight or who have noticed differences in their eating habits while on these drugs should consult a doctor.
Though Claritin and Zyrtec last for around 16 hours (8-hour half-life) in the body, the two drugs are metabolized differently.
Claritin's is excreted about equally through the kidneys via urination and through the digestive system via feces (around 40% both ways); trace amounts of the drug, unmetabolized, may remain in the urine. In contrast, about 70% of Zyrtec is excreted via urination, with half of the drug remaining unmetabolized; another 10% is expelled through feces.
How long it takes for Claritin or Zyrtec to work varies slightly by person. As Claritin is often used as a preventative medication, it may take several days for it to affect some patients. Zyrtec usually has faster results, but it, too, may take time, depending on severity of symptoms. Both should work very well within 5-7 days of use, and many will experience allergy relief on the first couple of days.
Loratadine is the active ingredient in Claritin, while Cetirizine is the active ingredient of Zyrtec. Both drugs are second-generation H1 histamine antagonists.