A 13-year-old girl with cyclic vomiting syndrome received a false-positive cannabinoid urine screen caused by intravenous pantoprazole, highlighting a drug interaction that mimics CHS screening.
Read this if you take heartburn medication and have had a surprising positive cannabis test.
Pantoprazole caused false-positive cannabis urine screen
What the researchers found
A 13-year-old with recurrent episodic vomiting was being screened for cannabis use because clinicians increasingly consider cannabinoid hyperemesis syndrome (CHS) in patients with cyclic vomiting. After receiving intravenous pantoprazole (a proton pump inhibitor) for her GI symptoms, her urine cannabinoid screen came back positive.
This was determined to be a false positive caused by the medication. The pantoprazole package insert references this potential interference, but the phenomenon had not been documented in the published medical literature. The interaction is particularly problematic because patients with cyclic vomiting are both likely to receive PPIs and likely to be screened for cannabis.
The case highlights the importance of confirming positive immunoassay results with more specific testing methods before attributing vomiting to cannabis use.
Why it matters
As CHS awareness grows, more vomiting patients are being screened for cannabis. If a common medication can cause false-positive results, patients could be wrongly diagnosed with CHS, leading to inappropriate treatment recommendations and potentially ignoring the true cause of their symptoms.
The numbers in context
One patient, age 13. False positive caused by intravenous pantoprazole (a PPI). The interference is documented in the pantoprazole package insert but not in published medical literature prior to this case.
How the study worked
Single case report describing a false-positive cannabinoid urine screen in a pediatric patient with cyclic vomiting syndrome who received intravenous pantoprazole, with discussion of the clinical implications.
What this study cannot tell us
Single case report. The mechanism of the false positive is not fully explained. It is unclear whether oral pantoprazole or other PPIs cause the same interference. Prevalence of this false-positive result is unknown.
How to read the evidence
Single case report documenting a previously unpublished drug-test interference.
When this study was published
Published in 2015. Awareness of PPI-cannabinoid screen interference may have improved since.
The bigger picture
Drug testing accuracy matters enormously when the result changes the diagnosis. As CHS becomes a more common consideration in emergency departments, understanding that common medications can cause false-positive cannabis screens prevents misdiagnosis.
Questions still open
- How common are PPI-induced false-positive cannabis screens? Do all PPIs cause this interference or only pantoprazole? Should confirmatory testing be standard before diagnosing CHS based on a positive screen?
Common questions
Can medications cause false-positive cannabis tests?
How can false positives be avoided?
Read the original research
13-year-old girl with recurrent, episodic, persistent vomiting: out of the pot and into the fire.
Pediatrics, 135(4), e1060-3
Citation
Felton, Diana; Zitomersky, Naamah; Manzi, Shannon; Lightdale, Jenifer R. (2015). 13-year-old girl with recurrent, episodic, persistent vomiting: out of the pot and into the fire.. Pediatrics, 135(4), e1060-3. https://doi.org/10.1542/peds.2014-2116
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