Can amoxicillin and clavulanate potassium mixed with ibuprofen make you fail for thc?

NO!!!!!!!!!: Not a chance in the world. For laboratory-confirmed tests, false negatives (the THC is in your system but the level is below the cut-off value) are common but false positives aren't. Sometimes people get surprised by a (+) test b/c they don't realize how long THC and its metabolites continue to be released in the urine. A regular +/- heavy user may test (+) a month after last use. Dr. Anne