Published on 12/22/2025, 12:00:00 AM
How Long Does Alcohol Stay on Your Breath? What a Breathalyzer Really Measures
If you’re asking “how long does alcohol stay on your breath?” you’re really asking something more practical:
How long can a breathalyzer still detect alcohol, and how long can that number hurt my case?
Alcohol can be detectable on your breath for hours, but there isn’t one timeline that fits everyone. The “how long” depends on your body, what you drank, when you drank it, and what kind of test you were given.
If you’re dealing with a DUI stop right now, start here:
The short answer
- Alcohol can stay on your breath for hours.
- You can’t reliably “speed it up.”
- Breath test results are a snapshot in time, and the details of how the test was done matter.
If you were pulled over and you’re trying to figure out what happens next, our best “start here” page is:
What “alcohol on your breath” actually means
People often mix up two things:
- The smell of alcohol (odor on your breath)
- Alcohol measured in breath testing (what a breathalyzer is trying to quantify)
Odor is not a number. A breath test is meant to measure breath alcohol concentration and estimate blood alcohol concentration (BAC).
That’s why two people can smell the same and blow very different numbers, or someone can smell like alcohol and still be under the legal limit.
The most common myths about clearing alcohol from your breath
Let’s clear up the stuff that gets people in trouble:
- Myth: coffee sobers you up. Coffee can make you feel more awake, but it doesn’t delete alcohol.
- Myth: a cold shower fixes it. A shower might wake you up. It does not change your BAC.
- Myth: you can beat a breathalyzer by breathing a certain way. Breath testing procedures and multiple samples are designed to reduce gamesmanship. Your best move is having counsel review what happened, not trying roadside tricks.
- Myth: if you wait long enough, you’ll definitely blow 0.00. Many people do reach 0.00. The problem is you can’t safely “guess” your timeline, especially if you’re making driving decisions.
What affects how long alcohol stays on your breath
There are a few big buckets that drive the timeline:
1) How much you drank (and how fast)
More alcohol generally means longer detectability. Drinking quickly can push you to a higher peak, which can stretch out the time window where a machine can still detect alcohol.
2) Time since your last drink
Breath alcohol changes over time. If testing happens soon after your last drink, the number can look different than it would later.
3) Food
Food can change how quickly alcohol is absorbed. This can affect when your breath alcohol peaks.
4) Your body
Your body clears alcohol on its own timeline. Weight, body composition, hydration, sleep, and overall health can influence how alcohol hits you and how long it lingers.
5) The testing conditions
In real DUI cases, the “how long” question is also tied to what test was given and how it was administered.
What happens during a typical Maryland breath testing timeline
Most people experience some version of this sequence:
- Traffic stop
- Roadside investigation
- This can include questions, observations, and sometimes field sobriety tests.
- Possible PBT (roadside handheld)
- Arrest decision
- Station testing
- This is where the evidential breath test usually happens.
If you want to understand the “stop to station” process in plain English, read:
PBT vs. “Breathalyzer” at the station (important for Maryland)
In Maryland, you’ll often see two very different breath tests:
- Roadside screening test (PBT): a handheld device used during a stop.
- Station breath test (Intoximeter): the certified evidential machine used after arrest.
If you’re trying to understand what happened in your case, read:
What a breathalyzer really measures in Maryland: the Intoximeter EC/IR II
When people say “breathalyzer” in Maryland, they’re often talking about the Intoximeter EC/IR II. We have a full breakdown here:
At a high level, the Intoximeter EC/IR II uses two methods:
- Infrared (IR): measures alcohol in a sample chamber using infrared light absorption.
- Fuel cell (electrochemical): uses a chemical reaction that creates an electrical current proportional to alcohol concentration.
This is also why you’ll hear lawyers talk about calibration, maintenance, operator training, and whether the proper steps were followed.
Why a breath number can change (and why that matters for “how long”)
People assume a breath test works like this:
“If I wait X hours, I’ll definitely blow 0.00.”
Real life is messier. Even if you’re not drinking anymore, breath alcohol can change based on timing and procedure.
Some common issues we see in DUI cases:
- Testing too soon or at an odd point in the timeline
- Mouth alcohol contamination (for example burping, vomiting, or having something in the mouth)
- Operator mistakes
- Machine certification or maintenance problems
- Paperwork problems
If you want the defense-focused view, read:
Mouth alcohol issues: why burping and vomiting come up so often
One of the most common ways a breath test gets attacked is mouth alcohol.
If alcohol is reintroduced into the mouth area shortly before testing (for example, by burping or vomiting), it can create a result that doesn’t cleanly reflect what’s going on in the body. That’s one reason Maryland breath testing rules include the observation period and mouth checks.
If you think this was an issue in your case, read:
The 20-minute observation period in Maryland (yes, it matters)
Maryland breath testing has strict protocols. One of the most important is the mandatory 20-minute observation period before a breath sample is taken.
The rule (summarized in our breath test challenge guide) requires that for at least 20 minutes before a breath sample is taken, the individual may not:
- Eat or drink
- Have any foreign substance in the mouth or respiratory tract
- Smoke
The person should be observed and mouth-checked during that period. (See: Challenging Breathalyzer Results in Maryland DUI Cases)
Why this matters for your question: if the observation period wasn’t done correctly, the test can be attacked, and that changes how much weight the “breath number” should carry.
“If I was under .08, am I safe?” Not always.
Many people assume only a .08 or higher result matters. In Maryland, breath results can have legal significance at different levels, and you can still be charged even if the number is below .08.
If this is your situation, read:
Should you blow? Refusal consequences and case strategy
People often find this article while deciding whether to provide a sample, or while looking back and wondering if refusing would have been better.
There are real legal and administrative consequences either way, and the “right” answer depends on your situation.
If you want the practical breakdown, read:
- Should I provide a breath sample if asked by a police officer in Maryland?
- The consequences of refusing a breathalyzer test in Maryland
Practical advice after a DUI stop (and why it impacts the breath test story)
If you’ve already been stopped or arrested, here’s what matters most:
- Don’t guess about timelines. Your case turns on facts, not rules of thumb.
- Save your paperwork. These cases are paperwork-heavy.
- Move fast on license issues. Many cases include an administrative track that is separate from court.
Start here:
FAQs
Q: How long does alcohol stay on your breath?
A: Often hours, but it depends on the person, the amount consumed, and the timing of the test. If you’re asking because of a DUI stop, the exact timeline and testing details matter as much as the general answer.
Q: Can I “flush it out” with water, coffee, exercise, or a shower?
A: You can mask odor and you can change how you feel, but you generally can’t force your body to eliminate alcohol on demand. Time is the main factor.
Q: Is a PBT the same as a breathalyzer?
A: No. In Maryland, a PBT is a roadside screening device. The certified station test is different. Start here: PBT vs Breathalyzer.
Q: What if my two breath samples were very different?
A: That can matter. Differences between samples can suggest problems with procedure, the device, or the test conditions. Read: Challenging breathalyzer results.
Q: Can a breath test be challenged in Maryland?
A: Yes. Depending on the facts, defenses can focus on the stop, procedure, observation period, operator certification, machine certification, calibration, and documentation. See: Challenging breathalyzer results.
Arrested after a DUI stop?
Don’t go it alone. The Maryland DUI lawyers at FrizWoods challenge stops, procedures, and testing, and work toward reduction, PBJ, or trial.
Questions about a breath test, observation period issues, or what the Intoximeter results mean? Contact us for a free consultation.
Related resources
- Intox EC/IR II explained
- PBT vs Breathalyzer
- What does PBT mean?
- Challenging breath test results
- What to do after a DUI
- DUI under the limit
