What Foods Should I Avoid With My Ignition Interlock?

Updated May 8, 2025

You may have heard rumors about certain foods causing a “false positive” reading on your Ignition Interlock. Is there any truth to these claims — and, if so, what besides alcohol shows up on a breathalyzer?

Because Smart Start breathalyzers use alcohol-specific detection technology, there are very few foods that can cause a false positive on a breathalyzer. Of the handful that can, simply washing your mouth out with water and waiting a few minutes will solve the problem — so there’s no need to actually avoid any foods. Let’s look at things that will set off an Interlock Device, so you can be aware of which foods deserve a little more caution when you’re using an IID.

Note: The terminology “false positive” is misleading. If your Interlock Device registers alcohol, it’s because there is alcohol present in the sample, even if it’s only a trace amount. We use the term sometimes in this article because it’s part of how many people talk about these issues.

Can spicy food set off a breathalyzer?

Spicy food will not cause a false positive on a Smart Start Interlock Device, or any modern IID. Go ahead and enjoy those jalapeño poppers or ghost pepper wings.

So where does this myth come from? You probably know that spicy food can irritate your digestive tract, causing gas expulsions like burps. On rare occasions, the small amounts of methane created by digestion could cause a false positive on older types of IID. 

These older IIDs were often sensitive to multiple types of compounds, so it was reasonable for drivers to wonder what could set off their Interlock Device. Fortunately, alcohol is the only substance that modern vehicle IIDs detect. If you’re using an IID from a reputable provider like Smart Start, don’t worry about spicy food.

Can sugar or carbs set off a breathalyzer?

Yes, but only under rare circumstances. Pastries like donuts and cinnamon rolls, or carb-heavy foods like pizza, can occasionally generate an extremely small amount of alcohol. This happens as they interact with yeasts that are naturally present in your mouth and the rest of your body. 

The good news is that this trace alcohol content dissipates within minutes. Therefore, if you indulge in a chocolate mint, a donut, or even a slice of pizza, wait a few minutes and rinse your mouth with water before taking a breath test with your Ignition Interlock. 

As a general recommendation, Smart Start always suggests rinsing your mouth with water before any breath test. This straightforward tip will help alleviate any concerns about trace alcohol readings on your breathalyzer. Waiting a few minutes after eating also allows sufficient time for the trace alcohol from the food to completely disperse. 

Can mouthwash affect a breathalyzer?

Yes, some mouthwash products and breath sprays contain alcohol. If you use one of these right before you blow into your IID, your device might register an alcohol reading. You can read more about alcohol and mouthwash here.

Again, we recommend waiting a few minutes and rinsing your mouth with water before using your Smart Start IID. If you want to avoid the risk entirely, many alcohol-free mouthwashes and breath sprays are available.

Will sugar alcohols show up on a breathalyzer?

Yes, it’s possible (but rare) to get a false positive on an IID from sugar alcohols like xylitol and erythritol. These sugar-like compounds are used as sweeteners in sugarless gum, diet energy drinks, and other sugar-free foods. These compounds won’t get you intoxicated — but while they’re in your mouth, they are similar enough to ethyl alcohol to potentially set off your IID when you give a breath sample. 

To avoid a false positive from sugar alcohols, we recommend the same advice as with other alcohol-containing foods: wash your mouth thoroughly with water, and wait a few minutes before giving your breath sample. 

Will kombucha show up on a breathalyzer?

It’s technically possible for kombucha to show up on a breathalyzer, since it’s a fermented beverage that may contain trace alcohol. However, the amounts of alcohol are so tiny that washing your mouth out with water and waiting a few minutes should always be sufficient to clear out any alcohol. Just make sure to avoid “hard” kombucha drinks, as these do contain significant amounts of alcohol.

Will coffee set off an Interlock Device?

No, coffee itself will not affect your Interlock Device reading. However, certain flavor additives to coffee, such as vanilla extract, can contain trace alcohol. If you’ve had your daily Starbucks vanilla latte before driving, it’s a good idea to wait before giving your breath sample and use water to rinse your mouth out.

While we’re on the subject, let’s dispel a common myth: Drinking coffee will not help you “sober up” after drinking alcohol. Stimulants like caffeine can make you feel less intoxicated, but they won’t do anything to lower your BAC or make driving more safe. If you’ve been drinking alcohol, your only option for passing an IID breath test is to wait until your BAC goes back to zero.

Will perfume, hand sanitizer, or aftershave show up on an Interlock Device?

Despite the high concentrations of alcohol present in these products, none of them should register as alcohol on your breath unless you’ve sprayed them in the air right before using your IID. If you’re putting on hairspray or cologne in the car, wait a few minutes before using your device.

Does smoking or vaping affect a breathalyzer test?

Smoking has no effect on breath alcohol tests. Vaping, however, can potentially register as alcohol in a breath sample if the liquid in your vape contains ethanol, according to a scientific study. Check the ingredients in your vape liquid and consider choosing an ethanol-free option if you have an IID.

If you smoke or vape, make sure that you don’t blow smoke or vapor into your IID. It’s unlikely to affect your IID reading, but it’s not good for the device and may cause a violation. Take a deep breath of clean air before you blow into your IID, and avoid blowing while you have a cigarette or cigar lit.

What substances does an Interlock Device detect?

Smart Start’s alcohol-specific Interlock Devices are designed to accurately detect alcohol, and only alcohol. You can read more about how breathalyzers work here. 

That said, it’s true that a handful of specific types of food can contain alcohol. To ensure your readings are accurate, simply follow our recommendations: rinse your mouth with water before testing, wait a few minutes if you’ve consumed alcohol-containing sweets, and rest assured that Smart Start’s technology can handle these situations effectively. 

If you have any further questions or need guidance regarding your Interlock program, our dedicated Customer Care team is always available to assist you. Don’t let food fails or Ignition Interlock myths hinder your progress—take control of your journey today. 

Need an Ignition Interlock? 

If you need to schedule an Ignition Interlock installation appointment, call our friendly, 24/7 Customer Care Center at (800) 831-3299 or fill out our online form below!