Semaglutides, Liraglutides, Tirzepatides & Ketone Production

Can use as a weight loss medication create false-positive breath testing results?

Counterpoint Volume 7: Issue 2 - Article 6 (September 2023; Updated June 2025)

An article for participants in the myCAMprogram

Jan Semenoff, BA, EMA
​Forensic Criminalist

Article information:

2200 words (approximately 11-14 minutes)
This is an important article, as the use of Semaglutide, liraglutide and tirzepatide  are now quite common as a weight control measure. What effect will their use have on reported Breath Alcohol Concentration readings (BrAC)?
Semaglutides, liraglutides and tirzepatides
are types of medication that mimic a hormone (Glucagon-Like Peptides, or simply GLP-1) that our bodies naturally produce when we eat. One important role of GLP-1 is to stimulate naturally occurring insulin, which in turn reduces blood glucose levels. 
Semaglutide, liraglutide and tirzepatide belong to the same class of drugs called Glucagon-Like Peptides-1 agonists (often referred to as GLP-1 receptor agonists) When semaglutide, liraglutide and tirzepatide mimic that hormone, the net effect is to put the body into ketosis.
There are three semaglutide products approved for use as weight control medication:
  • Ozempic ™ injection
  • Wegovy ™ injection, and
  • Rybelsus ™ tablets
​There are two liraglutide products approved for use as weight control medication:
  • Victoza ™ injection
  • Saxenda ™ injection
There is one tirzepatide product approved for use as diabetic and weight control medications:
  • Mounjaro ™ injection
They all require a prescription, and no generic versions are available or approved. They have been approved for the treatment of Type II Diabetes, and for weight loss under specific conditions.

Blood Sugar Disorders

Hyperglycemia

GLP-I receptor agonists (semaglutide, liraglutide and tirzepatide) are used extensively, and effectively, in type II diabetics to control hyperglycemia.
​Hyperglycemia is the condition where high blood sugars occur. This may happen if your client did not take enough or skip a dose of their diabetic medication, eat too much food rich in sugars, or does not follow their meal plan. It may also occur with flu like symptoms, when they are running a fever or infection, or have not exercised as much as usual. 
Signs and Symptoms of Hyperglycemia (high blood sugar) include:
  • Blurred vision, drowsiness, 
  • dry mouth, or unusual thirst
  • Flushed, dry skin, 
  • Fruit-like breath odor, often mistaken for alcohol consumption
  • Increased urination (in both frequency and amount), 
  • Ketones in the urine (often dark urine with an unusual odor),
  • Loss of appetite, stomach ache, nausea, or vomiting, 
  • Tiredness or extreme fatigue, 
  • Trouble breathing (rapid and deep), 
  • Lowered level of consciousness or unconsciousness.
​If symptoms of high blood sugar occur, diabetics are taught to check their blood sugar levels and then call their health care provider for instructions. 
​Semaglutides may cause some people to be agitated, irritable, confused, or display other abnormal behaviors. They may also cause some people to have sudden or strong feelings, including feeling nervous, depressed, angry, restless, violent, or fearful. 
​Semaglutides have been proven beneficial in treating type II diabetes. However, when used as a weight loss medication in non-diabetics, they can cause a significant drop in blood glucose levels which may result in serious hypoglycemia. 

Hypoglycemia

Hypoglycemia is the condition where low blood glucose levels occur. The signs of hypoglycemia are virtually congruent with the signs and symptoms of intoxication or impairment, including confusion, sweating, dizziness, weakness, the appearance of impairment or intoxication, and slurred speech.
Signs versus Symptoms - An important distinction
A sign is something externally observable. A symptom is something the patient will complain about.
As an example, the appearance of impairment is a sign. Being very thirsty is a symptom.
​Signs and Symptoms of Hypoglycemia (low blood sugar) include: 
  • Anxiety, or appearance of nervousness, 
  • The appearance of impairment or intoxication, 
  • Confusion, and difficulty with thinking and comprehension 
  • Drowsiness, 
  • Nausea or vomiting
  • Shakiness, 
  • slurred speech, or 
  • Unusual tiredness or weakness.
  • Cold sweats, with cool, pale skin
These are virtually congruent with the signs and symptoms of intoxication or impairment. Other symptoms include:
  • Excessive hunger, or thirst
  • Rapid heart rate, 
  • Headache (continuing), 
  • Nightmares and restless sleep, 
  • Blurred vision
Both semaglutides and liraglutides have been reported as associative or responsible for serious hypoglycemia. Semaglutide and Liraglutide can also increase the risk of Hypoglycemia when used together with other medicine (medically referred to as concomitant use) like insulin to lower blood sugar. 
Additionally, liraglutide specifically increase levels of delayed gastric emptying, called Gastroparesis. In 2018, one case was reported where a man presented at the emergency department with extreme delayed gastric emptying without mechanical obstruction. His symptoms had worsened over the course of one-week, requiring suctioning of more than one litre of fluid from his stomach. As a result, the consumption of food or liquids, including alcohol, may not follow normal expectations of absorption and clearance. 
​Low blood sugars also could occur if your client delayed or missed a meal or snack, exercised more than is typical, drank alcohol, or was unable to eat due to nausea or vomiting. 
​Practice Tip (When your client is Diabetic):
Stressful events will often trigger episodes of low blood sugar in diabetics. Court, as you are aware, can be a stressful event.
​
If symptoms of low blood sugar occur:
 - Have your client eat glucose tablets or gel, corn syrup, honey, or sugar cubes, or drink fruit juice, non-diet soft drinks, or sugar dissolved in water to relieve the symptoms.
- Also, have them check their blood for low blood sugar. Glucagon is used in emergency situations when severe symptoms including seizures or unconsciousness occur.
- Have a glucagon kit available (if required) and have someone available who knows how to use it, preferably a family member. 

​Semaglutides and Liraglutides Cause Ketosis Which Burns Fat

Semaglutide, liraglutide and tirzepatide as the New Keto Diet

​The Atkin’s (Low Carb) diet was the most popular diet for over a decade made famous by the cardiologist Robert Atkins. This diet is still very popular today, and is the type of diet people are following when they are on a low-carbohydrate diet, in other words, when they are avoiding simple carbs (breads and pastas), and complex sugars (cookies and candies). 
Semaglutide, liraglutide and tirzepatide have been shown to be effective at inducing and sustaining weight loss in a population of obese patients including those with hypertension, cholesterol imbalances, type 2 diabetes and obstructive sleep apnea.

​The Effects of Fasting on Breath Alcohol Readings

In essence, the use of semaglutide, liraglutide and tirzepatide creates a fasting condition considered more efficacious than a simple fasting diet. Fasting is designed to produce ketogenic conditions. When subject to fasting conditions, the body will begin to metabolize stored fats, creating the medical condition Ketonemia. Ketone levels will then begin to rise in the blood and urine. This creates a situation where the person becomes hypoglycemic from a cause other than too much insulin. Ketosis can be smelled on a person’s breath and is commonly dismissed as alcohol consumption.
​The initial situation for this hypoglycemic state is a rising level of ketones (b-hydroxybutyrate in the blood that is first metabolized to form Acetoacetate, then Acetone which can lead to increased levels of Isopropanol). It has also been demonstrated that the acetone is not a total waste product, being then converted into isopropanol through normal metabolism. This is an important step to consider. The alcohol produced, isopropanol, is NOT an alcohol that can be consumed safely by humans and is a toxic by-product of the ketogenic state.
Bailey (1990) reported a patient presented at an emergency department who tested positive for isopropanol who was in fact in a ketogenic state, and who had not consumed alcohol. 
​In 2007, internationally noted toxicologist Dr. A.W. Jones (with S. Rossner) reported an instance of a false-positive breath test in a fuel-cell interlock device from a person on a ketogenic diet who was an absolute abstainer from alcohol. It is believed that the increased levels of ketones, including acetone that is known to be biotransformed into isopropanol by the action of liver alcohol dehydrogenase leads to this false-positive effect on the fuel cell device. They concluded that the side effects of the ketogenic diet warrant caution and further evaluation by authorities during breath alcohol testing.
​The fuel cell component breath alcohol testers are not immune to the effects of the ketone bodies and isopropanol on the reading obtained. They are designed to identify the presence and concentration of ethanol. To a certain extent, all alcohols, and many other hydrocarbons, appear as ethanol to fuel cell instruments, and can routinely report a falsely elevated BrAC reading. Isopropanol as an alcohol. 
​Laakso et al, (2004) studied the effect of various volatile solvents for potential interference with breath alcohol analysis using the Drager 7110 evidentiary breath analyzer which uses a fuel cell to determine the presence and concentration of ethanol. They concluded that acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, and diethyl ether did not significantly interfere with the fuel cells breath alcohol measurement, but both propyl alcohol and isopropyl alcohol had a significant effect during breath alcohol measurement using fuel cells. 
In 2019 a case report was made to the publication Military Medicine regarding a United States Navy sailor who reported for duty and was screened positive with a BrAC reading of 0.026 g/dL. He denied any consumption of alcohol and was placed on duty as he was asymptomatic of impairment indicia. During his shift, under the watchful eyes of supervisors who confirmed zero alcohol consumption, his reported BrAC readings fluctuated from a low of 0.022 g/dL to a high of 0.048 g/dL. The sailor had previously lost about 55 pounds, which was attributed to his recent return from "an arduous submarine deployment". Both his blood glucose and A1c levels were very high, and he was subsequently diagnosed with diabetes.
​The blood to air partition ratio for isopropanol has an accepted value of about 1370:1. The partition ratio for ethanol has been legislatively accepted at 2100:1. Therefore, any trace levels of isopropanol found within the body would have an exaggerated effect on the readings obtained on a device calibrated at 2100:1. It has also been reported that blood levels of isopropanol have a tendency towards very low elimination rates in the body (Jones, 1996).
​Acetone amounts are even more volatile, with a reported blood to air partition ratio of about 130:1. This is considered extremely high when compared to many other volatile organic compounds. It has long been recognized that small amounts of acetone are also endogenously produced in the human body and a by-product of normal fat metabolism. (Wagaeus et al, 1981). Therefore, even trace amounts of acetone in the breath of a test subject will have a profound effect on the breath reading, as the breath testing device is calibrated to believe 2100 parts are present when read, rather than the actual level of 130 parts. In other words, a trace amount of acetone will be considered to produce an effect more than 15 times that of ethanol. 
​It has been identified by various researchers that certain hydrocarbon compounds, including isopropanol and acetone, cause inflated breath alcohol readings on various breath testing devices that are often not detected by the testing devices themselves (Hak, 1995, Jones et al, 1996, Caldwell & Kim, 1997, Bell et al, 1992, Logan et al, 1994 and Memari, 1999). 
​It should be noted that once a ketogenic diet, or when fasting conditions have begun, the measurable level of acetone in the breath rises steadily, increasing exponentially over the first 2-3 days, and after a week or so, achieve a consistent elevated state. Fasting conditions can produce levels of acetone in the breath that exceeds that of diabetics suffering from Ketoacidosis. Until the person consumes a high calorie or high carbohydrate meal, their breath acetone levels are considerable. 
​More importantly, studies indicate that these levels remain high before they begin to drop to baseline levels after consumption of a significant amount (about 500 calories) at a minimum. A protein rich meal will return a person to baseline levels within 5-6 hours, and a heavy meal will return a prolonged fast to baseline values within 16 hours. (Anderson, 2015). Any consumption of a minor amount of ethanol would not appreciably alter the underlying ketosis, nor eliminate its false positive effect on the fuel cell. It would not create an increase in measurable blood glucose levels.
​A rise in blood glucose levels does not immediately create a reduction in endogenous acetone, as the blood sugars must be processed by the naturally occurring insulin in the pancreas before ketone bodies are metabolized, and this takes several hours to occur once the blood glucose levels are replenished. As such, the recent introduction of sugars into the system does not immediately correlate to a reduction of endogenous breath ketone levels. 
​I was once asked to reproduce the results of an experiment performed by the Laboratoire de sciences judiciaires et de medecine legale – Quebec of (R. v. BUI, Quebec 2016) in 2016. This involved a gentleman in a state of ketoacidosis. The results of my experimentation indicate that one of the fuel cell based alcohol testers (Intoximeter’s Alco-Sensor FST) generated additive results with a false-positive reading between 0.053 – 0.100 g/dL higher than the true value in the presence of the acetone and isopropanol produced by a ketogenic diet. 
​Falsely adding 0.100 g/dL to a reported breath reading is highly significant.
​It should be noted that my experimentation was performed in vitro, using an alcohol simulator with a simulator solution of a known ethanol concentration. It is the action of the Volatile Organic Compounds (VOCs) on the fuel cell that produces the false positive effect regardless of its source.
​As with false positives generated by recent consumption (the so-called mouth alcohol effect), any VOCs present on the breath of the test subject will be additive to any underlying blood alcohol concentration.
Through the combination of intermittent fasting and much smaller eating portions, semaglutides and liraglutides can result in ketones measurable in urine in just a few days. As such the body is preferentially using fat as its energy source and the person begins to lose fat, and not lean muscle mass. 

Where does this leave us?

It is well understood that semaglutides and liraglutides are used effectively to control hyperglycemia. When mimicking the GLP-1 hormone, the body is put into ketosis. When used as a weight loss medication, they can cause a severe drop in blood glucose levels leading to hypoglycemia, with signs and symptoms remarkably consistent to the indicia of intoxication or impairment 
​What we don’t know is at what level the ketones can be found on the breath from semaglutide for liraglutide use, and to what extent those ketones may mimic ethanol in a breath testing device. We do know that ketones found endogenously on the breath can create false positive readings on certain breath testing devices.
​I am left to reasonably conclude, as have other researchers, that a combination of substances in fuel cell breath testing devices may falsely over-report the true BrAC level, even if that true value is zero. It should be noted that none of the fuel cell devices currently available have the capability of incorporating an interferent detector algorithm or component to screen for interferent chemicals in their reported analysis for BrAC levels. It is simply beyond the capability of fuel cell technology.
As such, persons routinely displaying symptoms caused by uncontrolled blood ketones or blood glucose levels are extremely poor candidates for breath alcohol testing. Emerging, newly diagnosed, or uncontrolled diabetics will have even greater instabilities due to the nature of their unmanaged and shifting blood glucose levels with corresponding blood ketone levels and are even worse candidates for accurate and reliable breath alcohol test results.
​Practice Tip:
I would strongly recommend that you add a section on Semaglutide use, either for diabetic control or as a weight loss regimen, into your client questionnaire. A trend may emerge, as it once did when the Atkin’s Diet became popular, associating their use with false-positive results, if any.

For more information about Ozempic, and its side effects, take a look at: Drugwatch.com  

https://www.drugwatch.com/drugs/ozempic/side-effects/

https://www.drugwatch.com/drugs/ozempic/ ​

    Question? Comments? Start the conversation here:

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Comments & Questions

Jan, great article. Do you know if the Intox 8000 is immune from the potential for false positives as the fuel cell devices are?
L.L. - Florida
​Early versions of the FL 8000 were highly prone to interferent effects. They seem to have tidied up the specificity over time through software updates…. Short answer…. We just do not know…

Thanks for your positive feedback!
​- Jan

For further study:

​ 
https://www.mayoclinic.org/drugs-supplements/semaglutide-subcutaneous-route/precautions/drg-20406730
 
https://menopausebetter.com/keto-and-semaglutide-a-risky-combination/#Common_Side_Effects
 
https://www.parathyroid.com/blog/top-10-ways-wegovy-causes-weight-loss
 
https://www.uclahealth.org/news/semaglutide-weight-loss-what-you-need-know
 
https://www.mayoclinic.org/drugs-supplements/semaglutide-oral-route/side-effects/drg-20492085

https://reference.medscape.com/drug/victoza-saxenda-liraglutide-999449

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5358074/

https://go.drugbank.com/drugs/DB06655
​

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