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A 46-year-old member asked:

how long should it take for my claritin (loratadine) to work?

3 doctor answers7 doctors weighed in
Dr. Gary Steven
Pediatric Allergy and Asthma 30 years experience
1-2 hours: Most medications take one to two hours to be absorbed into the blood stream. Some, such as steroids, need to be taken for several days to build up to their full effect, but this is not the case with antihistamines.
Dr. Michael P Vaughn
Allergy and Immunology 34 years experience
typically, only persons with mild allergies can take an anti-histamine such as claritin with complete control of nasal symptoms, head to head studies favor nasal steroids for control of symptoms.
Mar 31, 2012
Dr. Jeffrey Rumbyrt
Allergy and Immunology 32 years experience
Up to 1 hour: Claritin (loratadine) can work relatively quickly in most people. That is, it usually works within 30 minutes. However, in some people it may take up to 60 minutes to have its full effect. If it is not working within that time, or if the duration of effect becomes less and less, seeing an allergy specialist for allergy testing would be recommended as other treatments may be more effective.
Dr. Michael Zacharisen
Allergy and Immunology 33 years experience
About 1.5 hours: Onset of clinical relief is about 1 hour for zyrtec and Allegra and about 1.5 hours for claritin (loratadine). To read the study, go to: http://www.Ncbi.Nlm.Nih.Gov/pubmed/15176489.

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CA
A 28-year-old member asked:

Which drugs interfere with alavert (loratadine)?

3 doctor answers3 doctors weighed in
Dr. Stephen Kimura
Allergy and Immunology 35 years experience
A few drugs: Amiodarone and darunavir. One used for cardiac arrhythmias and the other for HIV infections. Both can cause loratidine levels to increase.
A 25-year-old member asked:

For how long does Claritin (loratadine) stay in your system?

3 doctor answers7 doctors weighed in
Dr. Alex Martinez
Specializes in Allergy
One day: Claritin (loratadine) 10 mg pill is dosed once daily. That's because it's effect will last about 24 hours, after that it's antihistamine effect wanes. However, Claritin is metabolized by the liver into another active compound called desloratadine, so the antihistamine effect can last a while. This is why most allergists have patients stop their Claritin a number of days before skin testing them.
A 50-year-old member asked:

How much time does it take Claritin (loratadine) to work?

2 doctor answers14 doctors weighed in
Dr. Alex Martinez
Specializes in Allergy
Within 1-2 hrs: Claritin (loratadine) is well-absorbed from the gastrointestinal tract and its effect is often felt within 1-2 hours. Claritin is metabolized in the liver into Desloratadine (the main ingredient in clarinex) which can stay in your system for many hours, allowing these antihistamines to be dosed once daily.
CA
A 39-year-old member asked:

I accidentally overdosed on loratadine. What can I do?

2 doctor answers5 doctors weighed in
Dr. Michael P Vaughn
Allergy and Immunology 34 years experience
Nothing: Claritin (loratadine) and most other nonsedating third generation antihistamines are very safe. The initial studies for Claritin (loratadine) were done at 40 mg (4 times the currently recommended dose). If a physical symptom is experienced after using any medication at an excessively high dose, the best resource is the "poison control" center. They are available 24/7 by calling 1-800-poison1.
A 42-year-old member asked:

How long does Claritin (loratadine) take to work?

1 doctor answer1 doctor weighed in
Dr. Michael Zacharisen
Allergy and Immunology 33 years experience
About 1.5 hours: The onset of clinical symptom relief is about 1.5 hours for claritin (loratadine). To read the study that compares this to zyrtec and Allegra go to: http://www.Ncbi.Nlm.Nih.Gov/pubmed/15176489.

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Last updated Aug 16, 2018

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