How Hair Drug Testing Detects Real Use
How accredited testing tells the difference between environmental contact and actual consumption.
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If you have ever wondered how a hair test tells the difference between someone who used a drug and someone who was merely around it, the answer comes down to one distinction: parent compounds versus metabolites.
It matters most in exactly the settings where a result carries weight — family law, child protection and the workplace — because it is what makes a result fair as well as accurate.
Parent compound or metabolite?
The parent compound is the drug itself. If someone uses cocaine, the parent compound is cocaine. A parent compound can reach the outside of the hair through handling or proximity to drug use, without the person having taken anything.
A metabolite is what the body produces as it breaks the drug down. It only forms once the drug has been ingested, inhaled or injected. Cocaine, for example, is converted by the body into benzoylecgonine.
Metabolites do not exist outside the body. So when a metabolite is found in hair, it is strong evidence the drug was actually used.
Why this matters in hair testing
Reputable laboratories test for both the parent drug and its metabolites. That dual check is what separates a defensible result from an arguable one:
| What it does | Why it matters |
|---|---|
| Metabolites confirm ingestion | Rules out surface contamination |
| Both must clear a cut-off | Stands up to legal challenge |
| Follows SoHT and NATA/ISO methods | Recognised standards, not in-house ones |
Common drugs and their metabolites
These are the parent compounds and metabolites a laboratory typically reports on:
| Drug taken | Parent compound | Metabolite(s) detected |
|---|---|---|
| Cocaine | Cocaine | Benzoylecgonine, norcocaine, cocaethylene |
| Heroin | Heroin | 6-MAM, morphine |
| Codeine | Codeine | Morphine (absence of 6-MAM) |
| Amphetamines | Amphetamine | No major metabolite — parent compound used |
| Methamphetamine | Methamphetamine | Amphetamine |
| MDMA (ecstasy) | MDMA | MDA |
| Cannabis | THC | THC-COOH (11-nor-9-carboxy-THC) |
| Alcohol | — | EtG (ethyl glucuronide) |
| Steroids | Testosterone, nandrolone | Various esters and metabolites |
The full 95-substance panel sets out everything covered as standard.
Reading a cocaine result
| Detected in hair | Likely interpretation |
|---|---|
| Cocaine only | Possible external contamination |
| Cocaine + benzoylecgonine | Confirmed use — the drug was ingested |
| Nothing detected | Negative result |
Reading a morphine and 6-MAM result
| Detected in hair | Likely interpretation | Notes |
|---|---|---|
| 6-MAM + morphine | Heroin use confirmed | 6-MAM is unique to heroin and appears only if heroin was used |
| Morphine only, no 6-MAM | Codeine or prescribed morphine | Morphine can arise from codeine metabolism or direct morphine use |
| Codeine + morphine, no 6-MAM | Likely codeine use | Codeine is partly converted to morphine in the body |
| Neither morphine nor 6-MAM | Negative for heroin and morphine | No opiate use detected, or below detection limits |
Detection thresholds and interpretation should always rest on an accredited laboratory report read in clinical context — which is also why poppy seeds come up so often in opiate discussions.
How accuracy is maintained
We use an Australian NATA-accredited laboratory working to ISO/IEC 17025 and the guidelines of the Society of Hair Testing. In practice that means:
- LC-MS/MS analysis, which identifies parent and metabolite compounds precisely
- both compounds must exceed set cut-off levels before a positive is reported
- a result that is documented well enough to be defended
Why cut-offs still matter
A positive is only reported when the detected level exceeds the laboratory’s cut-off threshold. Those thresholds exist to prevent:
- false positives from passive exposure
- over-reporting from ultra-sensitive instruments
- challenges to results that cannot be supported
Our laboratory uses a cut-off of 20 pg/mg for benzoylecgonine, the cocaine metabolite. That is sensitive enough to detect genuine use while leaving room for the incidental. The cut-offs for every substance are published, along with what a low, medium or high reading indicates.
The bottom line
- A parent drug on its own may come from use or from contamination.
- A metabolite is evidence the drug was taken.
- A test covering both is more accurate and easier to defend.
If you are being tested, that is the safeguard working in your favour as much as against it: a positive means the substance was used, not simply touched or breathed in passing.
