Some substances will affect the test and could give you a false positive.
Mouthwash: Some mouthwash brands and sprays have up to 30 percent alcohol; these will definitely create a positive test on your interlock. We recommend that you switch to a non-alcoholic mouthwash while using the ignition interlock device. However, alcohol levels from mouthwash or sprays should start to drop within 15 minutes, and washing your mouth out with water will help it drop faster. We recommend rinsing your mouth with water before testing.
Certain foods: Most foods will not cause the ignition interlock device to fail. However, you should be aware that certain candies and foods that may register a failed test unless you take precautions (like rinsing your mouth with water) prior to testing. For example, sugar and active yeast in some bread products (e.g.; cinnamon rolls, doughnuts) can combine to create a low-level alcohol reading. Simply rinse your mouth with water before the test to eliminate the remaining food. Alcohol-filled chocolates will register a fail; however, the alcohol in the chocolate will begin to decline in three minutes, so if you wait a few minutes before blowing into the device, it should not register a fail. Gum and candy without alcohol content will not create a false positive test.
Cigarette smoke and snuff: Always take a few deep breaths before attempting a test if you are a smoker. While cigarette smoke does not affect the interlock reading, you should never blow smoke into the unit.
Perfume, hairspray, after-shave or cologne: Most perfumes and colognes contain alcohol, but the interlock will not react to these substances on your skin, even if they’re used in heavy concentrations.