Alcohol testing: a guide to test types and detection windows

The length of time alcohol can be detected in the body depends on the type of sample being tested and the method of analysis.

While a roadside breath test can show whether someone is currently over the legal drink-drive limit, laboratory tests can reveal whether alcohol has been consumed weeks or even months earlier.

Understanding detection windows is important for several reasons:

• Solicitors and legal professionals – to select the most appropriate test for court proceedings, licensing hearings, or other legal matters.
• Social workers and local authorities – to monitor alcohol use in safeguarding or child welfare cases.
• Employers and occupational health providers – when alcohol testing is part of workplace policy or return-to-work programmes.

Here, we outline the different types of alcohol tests available at AlphaBiolabs, their uses, and the detection windows for each test type.

Alcohol testing options

At AlphaBiolabs, we offer a wide range of alcohol testing options, each designed for a specific detection window and use case:

• Breath alcohol testing – shows current intoxication, accurate to the time of testing.
• Blood alcohol testing (PEth, CDT, LFT, MCV) – provides evidence of drinking behaviour over the past 4 weeks.
• Hair alcohol testing (EtG/EtPa) – provides evidence of chronic & excessive consumption or abstinence from one month to 6 months (head hair), or up to 12 months (body hair). 
• Nail alcohol testing (EtG) – monitors abstinence or chronic & excessive consumption for up to 6 months (fingernail clippings) or for up to 12 months (toenail clippings).
• SCRAM CAM® – alcohol monitoring device worn around the ankle that can detect traces of alcohol in sweat, for detecting alcohol consumption in real time.

Which test do I need?

Choosing the right alcohol test depends on the timeframe you need to assess and the purpose of the results.

• I need to confirm whether or not drinking has taken place in the last few hours → Breath alcohol testing
• I need to evidence whether or not drinking has taken place over the past 4 weeks → Blood alcohol testing
• I need a month-long view (or longer) of abstinence or chronic & excessive alcohol consumption → Hair (EtG/EtPa) or Nail (EtG) testing 
• I need continuous monitoring of alcohol use → SCRAM CAM®

If you’re unsure which test is right for you, our in-house specialists can help you choose the most appropriate option for your circumstances.

Court-approved alcohol testing

Our alcohol testing services have been specifically designed to meet the requirements of legal professionals, social workers, local authorities and employers looking for legally-admissible results.

Samples are collected by a trained AlphaBiolabs sample collector under strict chain of custody conditions, ensuring the results can be used in court or for other official purposes.

Our breath, blood, hair, nail and SCRAM CAM® tests can all be used for legal matters, including by family law solicitors and social workers working on child welfare, safeguarding, and custody cases.

We also offer FREE sample collection for legally-instructed tests from our walk-in centres – a service unique to AlphaBiolabs.

How each alcohol test works

Each alcohol test detects drinking behaviour over a different period and serves a specific purpose. Understanding the benefits can help you choose the most suitable method for your needs.

Breath Alcohol Testing

• Detection window: Up to 24 hours, depending on how much alcohol has been consumed; measures breath alcohol concentration at the time of testing.
• Best for: Checking whether a person is currently under the influence.
• Benefits: Instant results; useful when an individual is suspected of being under the influence of alcohol and immediate results are required, or where sobriety needs to be tested (e.g. to ensure compliance with court orders during child welfare and custody cases).   

Finger prick PEth Alcohol Testing / Blood Alcohol Testing

• Detection window: up to 4 weeks.
• Best for: Medium-term monitoring of drinking behaviour.
• Benefits: Highly specific alcohol biomarker and the gold standard of blood alcohol tests. Reliable for evidencing regular consumption – including changed patterns of consumption – or abstinence. Quick, virtually pain-free blood collection (finger prick).  
• Complement with CDT, LFT and MCV blood alcohol tests for a comprehensive insight.

Learn more: Blood Alcohol Testing

Hair Alcohol Testing (EtG/EtPa biomarkers)

• Detection window: Around 1 month per 1 cm of hair length; up to 6 months (head hair), or up to 12 months (body hair).
• Best for: Establishing long-term chronic & excessive alcohol consumption or abstinence.
• Benefits: Non-invasive sample collection. Can provide a segmented month-by-month history, depending on length of head hair available.
• Complement with blood alcohol testing, for comprehensive insight.

Learn more: Hair Alcohol Testing

Nail alcohol testing (EtG biomarker)

• Detection window: Up to approx. 6 months (fingernails) or up to approx. 12 months (toenails)
• Best for: Long-term overview when hair is unavailable.
• Benefits: Simple collection; unaffected by hair treatments.
• Complement to other forms of alcohol testing (e.g. blood alcohol/PEth testing).

Learn more: Nail Alcohol Testing

SCRAM CAM®

• Detection window: 24/7 transdermal alcohol detection (traces of alcohol in sweat).
• Best for: Abstinence or compliance programmes where continuous monitoring is needed.
• Benefits: Tamper-proof, can be worn around the ankle for as long as required, state-of-the-art technology, notification of alcohol consumption within 24 hours of a confirmed drinking event, gain insight into a participant’s drinking activities over a defined period.

Preparing for an alcohol test

Legal testing must follow strict chain of custody procedures to ensure that results are admissible in court or meet professional standards.

Sample donors must:

• Bring valid photo ID to the appointment (e.g. passport or driving licence) to confirm their identity.
• Attend a booked appointment with a professional AlphaBiolabs sample collector.
• Follow any pre-collection guidance given – for example, avoiding chemical treatments (bleaching, dyeing, perming) before a hair alcohol test, or removing any artificial nail applications before a nail alcohol test.
• Provide medication details – prepare details of any medication they’re taking, including names, doses, and frequency, as this can be important when interpreting results.

Related: What to expect at a hair sample collection appointment

Accredited alcohol testing you can trust

Understanding how long alcohol stays in the body – and the testing options available – is key to helping you choose the right test to suit your requirements.

AlphaBiolabs provides fast, accurate alcohol testing for legal purposes, with expert guidance to help you find the most suitable option.

More reasons to choose us for alcohol testing:

• Rapid results from our ISO 17025-accredited laboratory
• Options for legal/official matters and the workplace
• Test for chronic and excessive alcohol consumption or abstinence
• Hair, blood, and nail samples analysed
• Breath testing and SCRAM CAM® also offered
• Member of the Society of Hair Testing with analysis carried out to internationally-agreed standards
• All legal pricing within Legal Aid Board rates
• FREE legally-instructed sample collections at our walk-in centres

Call us on 01 402 9466 or email info@alphabiolabs.ie to arrange your alcohol test today.