What may prescription and over-the-counter drugs contain that could affect testing?

Prescription and over-the-counter drugs can contain substances such as hidden alcohol or codeine that may significantly impact testing results. Many medications can have psychoactive effects or influence the body's metabolic pathways, which may lead to either false positives or alterations in standard test results. For example, certain cough syrups or pain relievers may contain codeine unbeknownst to the patient, which is classified as a controlled substance and can flag a drug test. Similarly, some medications may have alcohol as an inactive ingredient or as a result of fermentation processes, which could also affect test outcomes.

The other options, while they may represent substances found in various products, do not typically present the same level of concern when it comes to affecting drug testing outcomes. For instance, caffeine is commonly consumed in various forms and is not usually tested for in standard drug panels. Excess vitamins and artificial sweeteners, while they can have health implications, are not substances that are likely to cause significant alterations in drug test results.