Understanding Methylamphetamine & Amphetamine Results
Methylamphetamine metabolises into amphetamine — which is why reading the two figures together matters, especially in court.
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Two lines on a report, two similar names, and a great deal riding on the difference. Methylamphetamine and amphetamine are related, and the relationship between the two numbers is what tells you which substance was actually taken.
Methylamphetamine metabolises into amphetamine
When someone uses methylamphetamine — also called methamphetamine — the body breaks part of it down into amphetamine. In hair, urine or blood you will usually see both, with the amphetamine level typically around 10–20% of the methylamphetamine concentration.
So a hair result showing methylamphetamine at 2,000 pg/mg would be expected to show amphetamine somewhere around 200–400 pg/mg.
What dexamphetamine is
Dexamphetamine is a specific form of amphetamine. For testing purposes, dexamphetamine and amphetamine are the same substance under different names.
It is lawfully prescribed in Australia for conditions including ADHD and narcolepsy, and it is also available illicitly. The test cannot tell you which, but the pattern of results narrows it down.
Reading the combinations
| What the report shows | What it indicates |
|---|---|
| Methylamphetamine, with some amphetamine | Methylamphetamine use. The amphetamine is a by-product of how the body breaks it down. |
| Amphetamine alone, no methylamphetamine | Most likely dexamphetamine — prescribed or otherwise. |
| Both, with amphetamine higher than expected | Usually methylamphetamine use, but additional dexamphetamine cannot be excluded. |
Why the distinction matters
Two conclusions follow, and both come up constantly in contested matters:
- A positive for methylamphetamine cannot be explained by prescribed dexamphetamine. The metabolism only runs one way.
- A positive for amphetamine alone does not prove methylamphetamine use.
In family law, workplace testing and criminal proceedings, that difference can decide the matter — which is why a prescription should always be declared at collection, and why a report is read in context rather than at face value.
If the result came from a urine screen rather than hair, it is worth reading why those produce false positives for methamphetamine before drawing any conclusion at all.
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