Active Ingredients (per inhaler): 50 mg Levmetamfetamine (nasal decongestant)
Inactive Ingredients: Bornyl acetate, camphor, lavender oil, and menthol.
As mentioned by Biscuit above, most chemicals come in two forms - a d-isomer and an l-isomer. They are mirror images of each other, but may have wildly different effects on the human body. With meth, the d-isomer is an enormously powerful stimulant. It's the one the you want. The l-isomer, as found in Vicks inhalers is a very mild stimulant. If used heavily enough, it will lead to a positive test for meth.
In fact, until Vicks recently changed its formulation, meth fans claimed to be able to manufacture the highly active form from the inhalers, and bought them by the armful.
from: Lycaeum --> Leda --> Methamphetamine Frequently Asked Questions:
"...[The Vicks Inhaler Method] from Phrack magazine, is the "tried and true method" for prepping meth from Vick's nasal inhalers. Vick's nasal inhalers contain "l-desoxyephedrine," another name for "l-methamphetamine." The l- isomer of methamphetamine is the relatively inactive one, usable as a (mild) nasal decongestant. The d- isomer is the one that every one wants and that Uncle Sam has declared is just too cool for any one except doctors.
The [recipe involving extracting the active ingredients from Vicks inhalers] would extract the l-meth from the inhalers and collect it and that's it. I'm sorry, but the Isomer Fairy can't wave her magick wand and reverse the chirality of the molecule. The only way to change between the two isomers is to oxidize the l-meth into phenylacetone, condense it with methylamine, then reduce it. Sorry, but soaking inhalers in HCl then separating the "juice" with Et2OH just won't do it. You'll get l-meth and that's that..."
BigTrancer