Understanding Methylamphetamine & Amphetamine Results in Hair Drug Testing

When it comes to interpreting hair drug test results, one common source of confusion is the relationship between methylamphetamine (also called methamphetamine) and amphetamine. Here’s how they’re connected — and why it matters for understanding your report.

1. Methylamphetamine Metabolises into Amphetamine

When someone uses methylamphetamine, their body breaks part of it down into amphetamine. In hair, urine, or blood, you’ll usually see both methylamphetamine and amphetamine present — with the amphetamine level typically about 10–20% of the methylamphetamine concentration.

Example:
If your hair test shows methylamphetamine at 2,000 pg/mg, you might expect amphetamine to be somewhere around 200–400 pg/mg.

2. What is Dexamphetamine?

Dexamphetamine is simply a specific form of amphetamine. In the context of drug testing, dexamphetamine and amphetamine are essentially the same thing — same, same — just different names.

Dexamphetamine can be prescribed legally in Australia for conditions such as ADHD or narcolepsy.
It can also be obtained illegally.

3. How Test Results Are Interpretedis

Methylamphetamine found (with some amphetamine present)
→ This result can only come from methylamphetamine use. The amphetamine in this case is just a by-product of how the body breaks it down.
Amphetamine found by itself (no methylamphetamine detected)
→ Most likely due to dexamphetamine use. This could be legal (prescribed medication) or illegal use.
Methylamphetamine AND amphetamine found
→ This usually means the amphetamine is coming from the methylamphetamine use — but it’s impossible to rule out whether some additional amphetamine might also be from dexamphetamine use.

4. Why This Distinction Matters

Understanding the relationship between these substances helps avoid misinterpretation. For example:

A positive for methylamphetamine cannot be explained by dexamphetamine use — even if the person is prescribed dexamphetamine.
A positive for amphetamine alone does not prove methylamphetamine use.

Correct interpretation is critical, especially in court proceedings, workplace testing, and family law cases where the difference can affect outcomes.

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