Zantac Causing Positive Amphetamine Test
Zantac can cause false-positives, but fortunately, there are confirmatory tests available.
If anyone gets a false positive for the presence of amphetamine using a urinalysis while taking ranitidine, and that sample is sent out to the lab for further examination, is it still possible to come back positive for methamphetamine?
Zantac (ranitidine), a H2-blocker, has been reported by various studies as a potentially causative agent when it comes to 'false-positive' results for amphetamine (e.g. Adderall) on urine drug tests (i.e. urinalysis) (1, 2).
If you received a 'positive' result for amphetamine on a urine drug test, there are several other 'confirmatory' tests that can be utilized that can correctly determine if the positive test is accurate in regard to actually containing the offending compound (methamphetamine in your case).
Urine Drug Testing
Urine drug testing is often utilized in many situations, including for employment or as part of a pain management regimen. Most commonly, the type of test used is an 'immunoassay' test, which work by utilizing antibodies to react to specific drug compounds, like amphetamine or opioids.
These immunoassay tests work as follows (3):
- When a specified drug compound is present in a urine sample, an antibody binds to it. This produces a reaction.
- When a reaction occurs, this is considered a 'positive' result.
Immunoassay urine tests are generally used as an initial screening only as they are associated with a relatively high rate of inadvertent 'cross-reactivity' and 'false-positives'. Cross-reactivity refers to drugs that are not being testing for reacting with the wrong antibody, causing a positive result (but is actually a 'false positive') (4).
Zantac-Amphetamine Drug Test
- Dimetapp (Brompheniramine)
- Sudafed PE (Phenylephrine)
- Vicks inhaler (l-methamphetamine)
'False-Positive' Confirmatory Tests
If you believe that your urine test was falsely positive, there fortunately are more accurate tests that can be utilized for confirmation. While immunoassay tests rely on antibody reactions, other tests can accurately identify specific drug compounds in a given sample, eliminating the risk of 'cross-reactivity'.
- Gas chromatography with mass spectrometry
- Liquid chromatography with mass spectrometry
The above tests aren't generally used for initial screenings due to their expense and the fact the urine based immunoassay drug tests provide far quicker results.
In the case you provided in your question, if Zantac (ranitidine) caused a false-positive, a confirmatory test would confirm or rule this out. Since the 'confirmatory tests' actually isolate and identify all compounds present in a sample, methamphetamine will either be present or not (unless there is a contamination issue).