Ezra asked
Does Zantac (ranitidine) cause false positives for methamphetamine?
Answer
Zantac (ranitidine), an H2 blocker for acid reflux and indigestion, has been reported to cause false positives on drugs tests for both amphetamine and methamphetamine according to various studies.
Other drugs that have been reported to cause false positives for methamphetamine include:
- Amantadine
- Brompheniramine
- Bupropion
- Chlorpromazine
- Desipramine
- Doxepin
- Phenylephrine
- Pseudoephedrine
- Trazodone
- Vicks inhaler
Why Can Zantac Cause False Positives For Methamphetamine?
The most common type of drug test used is a simple, urine based immunoassay test. Immunoassay tests include the EIA (Enzyme Linked Immunoassay) test and the CEDIA (Closed Enzyme Donor Immunoassay) test, which use similar principles.
Immunoassay tests work by utilizing antibodies to react to specific drug compounds. When a specified drug is present in a test urine sample, an antibody binds to it, which produces a reaction and is recorded as a "positive" test.
Unfortunately with immunoassay urine tests, there can be a significant problem with 'cross-reactivity'. Drugs that are NOT being tested for can occasionally react with the wrong antibody (i.e. 'cross react'), resulting in a 'false positive'. As mentioned above, Zantac has been reported to 'cross-react' with antibodies that are supposed to bind to methamphetamine or related metabolites.
Immunoassay tests are known to be subject to false positives. Fortunately, test results can be confirmed or refuted via more specific tests such as via gas or liquid chromatography.
