Following the normal dosing instructions, cough medicine will not produce a blood alcohol reading.

Yes, people with asthma can typically provide breath samples.

This belief is incorrect. A penny under the tongue does not contribute to or alter the breath reading.

Dentures and tongue rings do not affect the breath test result as long as a 20 minute observation is performed.

To allow any residual mouth alcohol to be absorbed.

Yes, breath tests are very accurate. The instrumentation is held to a standard of 3% or 0.003 g/210 L of vapor (whichever is greater) for accuracy, and 0.003 g/210 L of vapor for precision.