This Is How Long Party Drugs Keep for

Dream with me for a moment. It's early January. You still haven't properly chucked the reminders of your New Year's hangover: three cans of half-full Holsten stuck rigid to your counter, a Domino's Family Deal's worth of empty boxes by the bin and an almost entirely full bag of cocaine on the kitchen table, which you bought at 6AM and did exactly two lines of, before guilt-tripping yourself into bed. You dispose of the trash and hide the coke, telling yourself you're going to be better this year, that you're not going to immediately buy drugs every time you have one-and-a-half pints.

It's April, now. Hot enough outside that you don't need a jacket. Someone in your group chat suggests a start-of-the-season al fresco sesh. A bell dings in your brain: that full gram of gak is still in your underwear drawer. But has it lost any of its potency? Do you need to take more than you usually do to make up for its time in storage? Pharmaceutical drugs are all sold with an expiration date – do illegal drugs expire too?

When it comes to medication, there are a number of factors that influence whether or not it's OK to take past its expiration date: the type of drug, how much time has passed and how it's been stored. With the exception of nitroglycerin, insulin and liquid antibiotics, most store-bought drugs are safe to use for up to a year after their official expiration date, as long as they have been stored properly. Proper storage means the medication has not been exposed to direct sunlight, heat or moisture, or extremely hot or cold temperatures.

Some scientific research indicates that medication may work for much longer still. A study conducted by the FDA in 2000 found that 90 percent of unused medications stockpiled by the US Military remained completely potent several years past expiration. The findings suggest that drug makers tend to be conservative with expiration dates, possibly in order to keep up market demand. The term "expiration date" itself is arguably a misnomer; the dates are simply the point to which pharmaceutical companies can guarantee a drug's maximum effectiveness.

So: okay, fine. But what about party drugs? According to this supposedly "popular analogy", if "the Egyptians had known how to make MDMA, we'd be finding MDMA in old crypts in the pyramids that's still good for consumption".

Admittedly, this theory was posited by a Reddit user who has since deleted their account – but it is partly supported by Dr Fernando Caudevilla, AKA Doctor X, a Spain-based online expert on cannabis, cocaine and synthetic drugs. "Most common recreational drugs have a long expiration date," he tells me over email. "Amphetamine and amphetamine derivatives – speed, crystal meth, MDMA, MDA, etc – are particularly stable and keep their pharmacological effects for many years, even decades. Drugs derived from plants – including cocaine – are a little less stable."

Back to that old baggie of yours. Drugs are never 100 percent safe – each comes with its own set of risks, which you mitigate by employing sensible harm reduction techniques. But that baggie: are its contents safe for consumption? Should you rack your lines a little bigger to make up for the time the drugs spent living with your socks?

"It really depends on how much light and moisture it's been exposed to, and what temperature it's been at," says Guy Jones, Technical Lead at Reagent Tests UK. "There's not really a formula where you can say, 'After X months it will lose 1 percent, and after Y months it will lose 2 percent,' because the conditions are so variable. As a rule of thumb: if you'd discovered it in a drawer after a year and you'd taken no special precautions, I wouldn’t be surprised if it had lost 2 to 3 percent, but unless it was literally soggy when it went into a drawer, I don't think it's an amount of potency loss you should adjust your dosage for. If it is kept in a cool, dark place in the absence of moisture, cocaine will typically be able to outlive a human being. Basically, you would never need to take more to account for the breakdown of it."

MDMA is an even more stable molecule; it doesn’t absorb any moisture from the air at all. According to Jones, "Unless it is literally damp to the touch, it will probably outlive a human, no matter what. If you leave it in direct sunlight it might slowly break down, but if you just store it in any normal place then it's not going to break down in any way. Sometimes pills do have things in them that slightly absorb moisture from the air, but that tends to just make the pill fall apart."

Although these compounds are relatively stable, the better the conditions you store your drugs in, the longer they are likely to last. In general, the four things you should try to avoid are air, heat, light and water. The optimum conditions for storage are dry, dark and away from oxygen. "The more of these conditions you can meet, the better, and if you can keep your drugs in an air-tight container that has no oxygen in it, these drugs will literally last forever," says Jones.

Essentially, unless you're an idiot who leaves your baggies on windowsills and in damp bathroom cabinets, your drugs will likely outlive you. One exception to this is LSD, which is particularly sensitive to light; leaving it in direct sunlight for a relatively short amount of time would cause a potentially noticeable amount of potency drop, due to the fragility of the molecule. Jones recommends using blotters, wrapping them in tinfoil and putting that inside a baggy, as the tinfoil keeps light out and the baggy keeps oxygen out. If kept in a freezer, it would last for years, but even keeping it in a sealed container in a drawer is enough to keep it for a year or so.

If you're planning to store cocaine for a long time, a dry silica gel packet inside of the baggie will absorb any moisture that's already there, and any that manages to penetrate through the plastic. In conclusion, then: unless you dropped them in a puddle or have been storing them in a sun-bed for some reason, your leftover drugs are just as strong as they ever were.