Can Claritin cause false positive drug tests? 

Can Claritin cause false positive drug tests? 

Claritin (Loratadine) may or may not cause false positive drug tests. Claritin is a second-generation antihistamine and is not categorized as a drug of abuse. 

This indicates that Claritin is not something standard drug tests look for and it is not included in the panel of drugs to be tested. However, Claritin may cause a false positive for Amphetamines (1). It is not associated with such a false positive in every case, but some of the cases are reported. 

However, these cases are common with preliminary drug urine immunoassays which are not so accurate and they may require further confirmatory tests to confirm the preliminary findings. 

If you’re going for highly accurate testing procedures, like Gas Chromatography – Mass spectroscopy (GC-MS), getting a false positive is not something you should worry about (2). 

This is because methods like GC-MS usually detect the exact chemical present in your body at the time of sample collection. 

How long does Claritin stay in your system? 

Claritin has a half-life of about 8-9 hours, which is the time taken by this medication to reduce its initial peak concentration to half. The remaining concentration further reduces to half within the next 8-9 hours. It usually takes 24 hours for Claritin to get completely removed from your body. 

This time duration can vary as people, who have an underlying disease like hepatic insufficiency that can delay drug metabolism, can take longer to get rid of the medication completely. 

How to avoid Claritin showing up on a drug test? 

You can avoid Claritin causing a false positive by not taking the medication in the last 24 hours before your test. This way your body will have enough time to metabolise and eliminate the last Claritin tablet you took. 

However, you can simply inform the drug testing authorities that you’re currently taking Claritin – a medication that is capable of causing a false positive. 

If you’re initially going for a proper testing procedure like Gas Chromatography – Mass spectroscopy (GC-MS), false positives are not something you should be worried about as procedures like GC-MS detect the exact drug present in your body. That leaves no room for a false positive. 

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Alyson Schwebach, Jennifer Ball. Urine Drug Screening: Minimizing False Positives and False Negatives to Optimize Patient Care. US Pharm. 2013;38(12):1-6. Available from:


Ramoo B, Funke M, Frazee C, Garg U. Comprehensive Urine Drug Screen by Gas Chromatography/Mass Spectrometry (GC/MS). Methods Mol Biol. 2016;1383:125-31. doi: 10.1007/978-1-4939-3252-8_15. PMID: 26660182. Available from: