I am Joel Brand, and I defend DUI cases across California. Over the last couple of years I have started asking every client a question I never used to ask: are you taking Ozempic, Wegovy, Mounjaro, Zepbound, Saxenda, or anything like them? A lot of people are surprised by the question. They came to talk about a breath test result, not about their prescriptions. But these medications, the class doctors call GLP-1 receptor agonists, do something to your digestive system that can matter a great deal to how alcohol shows up in your body and in a machine. If you were on one of these when you were arrested, your attorney needs to know on day one.
What These Medications Actually Do
Semaglutide, tirzepatide, liraglutide and their relatives work in several ways, but one of the central ones is that they slow gastric emptying. Your stomach holds onto its contents longer and releases them into the small intestine more slowly than it otherwise would. That is a large part of why people on these drugs feel full for hours after a small meal. It is not a side effect that happens to some patients and not others. Slowed stomach emptying is a core mechanism of how the medication works.
That single fact has consequences for a DUI case, because alcohol is absorbed mostly in the small intestine, not the stomach. Anything that changes how fast your stomach hands alcohol off downstream changes how fast alcohol reaches your blood.
Alcohol Absorption Does Not Follow the Usual Curve
The entire framework of a chemical test DUI rests on assumptions about how a typical body handles alcohol. Alcohol goes in, it absorbs over a fairly predictable window, blood alcohol concentration peaks, and then it burns off at a fairly steady rate. Every calculation the prosecution runs downstream of your test result depends on that curve holding true.
Early research on GLP-1 medications and alcohol suggests the curve does not hold the same way. In a small controlled study published in 2025, participants on maintenance doses of these medications who drank a measured amount of alcohol showed a noticeably delayed rise in breath alcohol concentration compared to participants who were not on the medication, and they reported feeling intoxicated later as well. I want to be careful about how far I push that. It was a preliminary study with a small number of participants, and it is not a rule of law or even settled science yet. But it points at something that follows logically from a mechanism nobody disputes. If your stomach is emptying slowly, the alcohol in it reaches your bloodstream on a different schedule.
Why Delayed Absorption Cuts Toward the Defense
Here is the practical problem for the prosecution. You are almost never tested at the moment you were driving. There is a stop, questioning, field sobriety tests, an arrest, a drive to a station, an observation period, and only then a test. An hour or more between the wheel and the machine is completely ordinary, and I have written before about the gap between the stop and the breathalyzer.
To close that gap, the prosecution's expert works backward from your test number to estimate what your blood alcohol was when you were actually driving. That exercise, called retrograde extrapolation, assumes you were past your peak and steadily eliminating by the time you were tested. If you were still absorbing when the machine ran, the number on the printout can be higher than what was in your blood at the wheel. That is the core of the rising blood alcohol defense, and slowed gastric emptying is exactly the kind of physiological fact that makes it live rather than theoretical.
I will also be honest about the other edge of this. If alcohol is hitting you more slowly, you may have felt fine when you decided to drive and then kept climbing afterward. That is not a defense to how you feel. It is a reason to understand the timeline in your own case with real precision.
Reflux, Nausea, and the Mouth Alcohol Problem
The second issue is separate from absorption and, in my experience, comes up more often. Nausea, vomiting, belching, and acid reflux are among the most commonly reported effects of these medications. Clinical trial data on semaglutide has reported nausea in a large share of patients and vomiting in a meaningful minority, and analyses have found the class associated with an increased risk of gastroesophageal reflux compared to placebo.
A breath machine does not sample your blood. It samples air and assumes every molecule of alcohol in that air came up from deep lung tissue. When stomach contents or stomach gas travel back up into your mouth or throat, that assumption breaks, and alcohol that never went through your lungs gets counted anyway. The result can be a reading well above your actual blood alcohol. I have written a full breakdown of this in the library articles on GERD and DUI in California and the mouth alcohol defense, and everything in them applies with equal force to reflux caused by a medication rather than by a chronic condition.
The Fifteen Minute Observation Period
California's breath testing regulations require the officer to continuously observe you for at least fifteen minutes before the test, and the point of that period is largely to catch exactly this problem. If you burp, belch, regurgitate, or vomit during those fifteen minutes, the clock is supposed to restart.
So I ask clients a very specific set of questions. Did you feel nauseated in the patrol car? Did you burp before you blew? Was the officer actually watching you, or filling out paperwork, or in the front seat while you sat in the back? Did anyone ask you whether you had reflux or had recently thrown up? On a GLP-1 medication, a burp during the observation period is not an unlucky coincidence. It is one of the expected effects of the drug you are on. Whether the officer noticed it, documented it, and restarted the clock is a factual question worth developing.
Low Blood Sugar Can Look Like Impairment
These medications also affect blood glucose, which is why many of them were approved for type 2 diabetes in the first place. Taken alongside insulin or a sulfonylurea, they can contribute to low blood sugar. Many people on them are also eating very little, sometimes skipping meals entirely for a day or more, and some are noticeably dehydrated from vomiting or diarrhea.
Low blood sugar produces confusion, slurred speech, unsteadiness, sweating, and slow responses. Those are the same observations an officer writes down as evidence of intoxication. Dehydration and fatigue degrade balance and coordination on their own. The one legged stand and the walk and turn are difficult for plenty of sober people under good conditions, and they are graded against a standard that assumes you are healthy, rested, and fed. See the diabetes defense and the article on medical conditions that can affect a DUI case for how this gets developed.
The Medication Itself Is Not a Drug DUI
I want to be clear about something so nobody misreads this post. These are not controlled substances, they are not sedatives, and taking one as prescribed is not itself driving under the influence of a drug. But California's DUI law reaches impairment by any drug, prescribed or not, and having a valid prescription does not immunize you if you were actually impaired. If your case involves alcohol plus other medications, or a drug charge rather than an alcohol one, read how prescription drugs affect your DUI defense and DUI of alcohol and drugs combined.
What About a Blood Test
A blood draw sidesteps the mouth alcohol problem entirely, because nothing in your mouth or esophagus reaches the vial. It does not sidestep the timing problem. A blood sample taken ninety minutes after you drove still has to be connected back to the moment you were behind the wheel, and delayed absorption complicates that connection the same way. Blood cases have their own set of issues around collection, preservation, and your right to have the sample retested, which I cover in the post on Title 17 and your right to a retest.
What I Need From You If You Are On One of These
None of this argues itself. Evidence has to exist before anyone can use it. If you were on a GLP-1 medication at the time of your arrest, start gathering the following now, while it is all still recoverable:
- The prescription itself, the prescribing physician, and the pharmacy record showing when you filled it.
- Your current dose and, critically, the date you started or last increased it. Digestive effects are usually strongest in the weeks following an increase.
- The date and time of your most recent injection or dose relative to the arrest.
- Anything you have documented about nausea, vomiting, reflux, or heartburn, including messages to your doctor, an app log, or pharmacy notes for an antacid.
- What you ate that day and when, along with what you drank, how much, and over what period.
- Any other medications, especially insulin or other diabetes medications.
This Is Not an Automatic Anything
I do not want anyone reading this to think a prescription bottle makes a case disappear. It does not. What it does is give a qualified expert a documented physiological basis to challenge assumptions the prosecution needs the jury to accept without thinking about them. Whether that goes anywhere depends on your test numbers, the timeline, the officer's report, the observation period, the instrument's maintenance history, and a dozen other facts specific to you. Some cases turn on it. Others do not. The only way to know is to look.
The mistake I see is not that people argue this badly. It is that nobody ever raises it, because the client never mentioned the medication and nobody asked.
Do Not Let the Ten Day Deadline Pass
Whatever the medical picture in your case looks like, the clock does not wait for it. You have ten days from your arrest to request a DMV hearing, and if that window closes your license suspension proceeds regardless of how strong your defense is in court. That deadline is the single most common thing people lose without realizing it. See the first ten days after a DUI and start there.
The Bottom Line
Millions of people in California are now taking a medication that deliberately slows their stomach, frequently causes reflux and nausea, and appears to change the timing of alcohol absorption. Breath testing was designed and validated long before any of that was common. That mismatch is worth investigating in your case, and it costs nothing to raise it.
If you were arrested for DUI in California and you are on a GLP-1 medication, tell your attorney at the first conversation, before anything else. If you want to talk it through with me, call. I answer my own phone, twenty four hours a day.