EtG test: can food or mouthwash cause a positive result?

Yes, an EtG test can also be triggered by food containing alcohol or by mouthwash, not just by drinks. EtG detects alcohol in the body, no matter where it comes from. If you are on an abstinence programme for the MPU (medical-psychological assessment, Medizinisch-Psychologische Untersuchung), you should therefore avoid anything that contains alcohol whenever in doubt.

What is EtG and why is it tested?

EtG stands for ethyl glucuronide and is a direct alcohol marker. The body produces EtG when it breaks down alcohol. If EtG is found, there was alcohol in the body.

For an MPU relating to alcohol, EtG is the standard marker for proof of abstinence (Abstinenznachweis). The tests follow the CTU criteria (chemical-toxicological analysis, Chemisch-Toxikologische Untersuchung) and must take place in a laboratory accredited to DIN EN ISO/IEC 17025. You can find an overview of the whole procedure on the page Proof of abstinence.

How long can EtG be detected?

EtG can be detected in urine for about 24 to 80 hours and in hair retrospectively for about 3 months. The detection windows therefore vary greatly depending on the type of sample.

The short window in urine is the reason why you are summoned at short notice. This is the only way to ensure that no use between two appointments goes undetected. The guide PEth level explained tells you more about the blood marker.

Can food or mouthwash trigger an EtG test?

Yes, food containing alcohol and mouthwashes can cause a positive EtG test. The test does not distinguish whether the alcohol came from a glass of wine, a sauce or a personal care product. It only shows that alcohol was taken in.

For you, this means: the risk does not only lie in deliberate drinking. Products where you do not even think of alcohol can also become a problem. How strong the effect of an individual product is cannot be stated in general terms. That is why the safe rule is: if in doubt, avoid it.

Which product groups should you keep an eye on?

Instead of a list of threshold amounts, which does not reliably exist, one simple question helps: does the product contain alcohol? Pay particular attention to these categories:

• mouthwashes and other oral care products that contain alcohol,
• dishes prepared or refined with alcohol,
• sweets and desserts that contain alcohol as an ingredient,
• drinks where you are not sure whether they are really alcohol-free.

This list is a cautious guide, not a complete list. What counts is always the list of ingredients – and, if in doubt, going without.

Why does a positive EtG result have such serious consequences?

A positive EtG result can invalidate your ongoing abstinence programme, and the abstinence clock then usually starts again. With a programme of 6 or 12 months, this means a considerable loss of time.

Here the MPU works according to the 0.0 rule: even a small „slip“ can invalidate the programme. This applies regardless of whether you drank deliberately or the alcohol came unnoticed through a product. That is why caution is worth more than any later explanation.

And if it happens anyway?

If a positive result does occur, you should on no account cover it up. A concealed incident that comes to light later destroys your credibility completely. It is better to put honestly into context what happened and make a clean restart. The guide Relapse during abstinence explains how to deal with this.

How do you protect your abstinence programme in everyday life?

The best way to protect your programme is to remove alcohol in every form from your daily life consistently. That sounds strict, but it is the simplest way to avoid unnecessary risks.

1. Read ingredient lists: check food, sweets and personal care products for alcohol or ethanol.
2. Change your oral care: use alcohol-free products during the programme.
3. Ask when eating out: in restaurants or when invited, ask whether dishes were prepared with alcohol.
4. Inform the people around you: tell family and friends that you are on an abstinence programme. This makes invitations easier.
5. Clear up uncertainties: if you have questions about products or medication, contact your laboratory or your doctor.
6. Secure your appointments: be reachable for short-notice summons and take your ID with you, because a missed appointment can do as much damage as a positive result.

Which formal rules apply to EtG testing?

An EtG test only counts for the MPU if it meets the formal requirements of the CTU criteria. A clean result alone is therefore not enough.

• Identity check: you show your ID every time you give a sample.
• Supervised sample: for urine, the sample is given under observation.
• Chain of custody: the sample chain from your identity to the laboratory is documented without gaps.
• Continuous programme: a missed or manipulated appointment can invalidate the whole programme.

So pay attention not only to what you eat and use, but also to being reachable and on time.

What role do liver values play alongside EtG?

Liver values such as GGT, GOT, GPT, MCV or CDT are only indirect markers and hardly play a role in proof of abstinence today. They are taken during the medical examination and can additionally show „good values“.

You provide the actual proof via EtG in urine or hair or via PEth in blood. Whether abstinence is required at all in your case or whether controlled drinking is an option depends on your file, as the page MPU for alcohol explains.

What you can do now

1. Go through your household: mouthwash, food, sweets – sort out or replace everything containing alcohol.
2. Clarify with your laboratory which type of sample (urine, hair, PEth) is planned for your programme.
3. Make the 0.0 rule a habit, including for food and personal care products.
4. Document your programme without gaps and keep all results in the original.
5. If you would like support for the MPU: find suitable preparation.