Cocaine and heroin are sold as white or off-white powders. They are very hard to tell apart. As someone else mentioned, cocaine produces local anesthesia, so that provides a "test" for users, but street drugs are rarely pure so there is always a chance that a batch of heroin has a local anesthetic in it so it produces a false positive (likely very rare though).

The thing that makes heroin masquerading as cocaine dangerous is that typical heroin doses are quite small (~10 mg) vs cocaine (~100 mg). If you get heroin instead of cocaine and snort your regular dose, it can easily be a fatal dose of heroin for a naive user.

> there is always a chance that a batch of heroin has a local anesthetic in it so it produces a false positive

This suggests that there is some motivation to pass heroine off as cocaine, rather than this being a supply-chain mixup. But then why sell heroine as the substitute? It seems like the street value of heroine would still be higher than other substances (say, talc with the local anesthetic). If you're dealing, why not just try and pass that off, increase your profit margin, and not invite criminal investigation into the deaths of your customers?

Or is the presumption here that some people are dealing with the purpose of causing harm?

I am far from an expert, but one possible scenario revolves around drug novices who are partying heavily, and a simple problem communicating. A group of tourists, well into a night of very heavy partying, could ask a random person for an ambiguous term (like 'powder') expecting to get cocaine. Perhaps that particular dealer only has heroin, which is technically a powder as well, so he/she sells it and thinks nothing of the transaction.

Moments later, some very intoxicated tourists dive into what they think is cocaine. They do a line each, don't get the cocaine feeling that perhaps one or two of them vaguely remember, but they assume that they just got badly cut drugs, so they dive in and do more.

Snorting heroin (especially if you think it is cocaine) is a surefire recipe to die because it tends to take a little longer to really kick in. And, because of its toxicity, there isn't a lot of room between getting high and dying.

Coke often gets cut with other much cheaper drugs that will simulate some effects of cocaine (such as numbing) so that users are less likely to realise how cut their drug is. (All coke will be cut at least somewhat, but if you're buying it you're hoping a.) fairly high purity and b.) cut with non-toxic non-drugs, rather than other drugs)

I'd be surprised if that didn't happen all the time with heroin too, though if heroin doesn't provide a numbing feeling then there's no motivation to specifically add a cheap numbing drug.. but numbing could well be an accidental side-affect of something that was added to dilute the % of heroin in each gram sold?

> Or is the presumption here that some people are dealing with the purpose of causing harm?

Could be. As [boefs mentions on Reddit](http://www.reddit.com/r/thenetherlands/comments/2npjx5/just_...), selling Heroin in the Netherlands is really hard.

The two most likely scenario's at this moment is that either someone got his hands on cheap Heroin and wanted to make a quick sell or that someone was ripped and sold a large quantity of Heroin and now wants to make some money off that. Either way, in the Netherlands you apparently hardly get rid of heroin, whereas coke is sold for much higher prices much easier.

Ah, the doses makes sense - I was figuring even if you couldn't tell the difference with a little taste or a tiny sniff, you wouldn't go line for line without realising it wasn't coke... but if one coke-sized line of heroin is enough to OD then even if you can spot the difference easily, all it takes is doing a line without checking and you're fucked.7

This was a plot device in Pulp Fiction.

The GGD site has information on how to tell them apart:

"Test it by placing a pinch of the powder on your tongue. If, within a few minutes, this does not have a numbing effect, it is not cocaine. It could be heroin instead."

http://www.ggd.amsterdam.nl/english/drugsalert/more-informat...

This on a government website is even more amazing from an American perspective than the linked flier. Talk about taking harm reduction seriously...

In addition the police think that the dealer does not know what he is selling. Heroin is much more expensive per gram than cocaine. And yes having seen both they would be pretty similar by sight. Especially in a little bag and poor lighting they would be remarkably similar. Given that the users are expecting cocaine, the dealer thinks he is selling cocaine and the drug is a white powder it is understandable that this is happening. Think Uma Thurman in Pulp Fiction.

What if you were to post a photo of yourself using drugs to social media? Could the UK police arrest you for that?

In South Korea they can and do arrest and prosecute people for photographic / recorded evidence of them doing drugs even while overseas.

I've no idea. I suspect that yes, since it's photographic evidence of what is a crime (possession), whereas if you just tweeted "I'm high as hell right now" that wouldn't be proof of a crime. But I also suspect they'd never bother to arrest for something like that unless you were dealing.

Even if they catch you with drugs on you, as much as possession (non-dealing) charges have high maximums - for class A drugs I think the maximum is 7 years prison + fine for possession or life in prison for dealing - realistically you're unlikely to get in much trouble for a small quantity. Weed unless you're a serious repeat offender, or a cop decides he hates you, you'll either get an on-the-spot official "caution" and fine up to £90, or more likely a non-recorded verbal warning and confiscation. For harder drugs police aren't meant to do that, but stories I've heard you're still more likely to get confiscation and possibly a caution.

I've even known weed dealers (low level) who've been caught and only had to give up the cash and weed they had on them.

No they wouldn't - it might provide basis for a search warrant if the pictured quantity is large enough, but they have no way of proving that the thing in the picture is actually cocaine vs baking sugar.

As a slightly related anecdote, a friend of a friend got caught with 11 grams of cocaine (supplying for a party, I think) and by the time he got to court he was being charged with possession of 4 grams, which reduced his "years in prison" with "a few months probation and a fine". No mention of where the 7 grams went in the months between.

Photographic evidence or CCTV, by itself, is almost never enough to reach a conviction.

That sounds like a good policy, but I feel like it could be taken a step further by allowing for possession in a medical emergency. It seems like it would be helpful to medics to have a sample of whatever it is that the person has taken.

In regards to edit 2, I couldnt agree more, if you are a tourist the street dealers in Amsterdam can be kind of nuts, one guy even followed me for almost 5 city blocks completely incredulous that I would not want to buy cocaine from him.

I actually thought they were great - I mean, I wouldn't trust their product, but all I've experienced multiple times there were people who whisper the name of the drug they're selling in your ear while walking past you in the opposite direction, never had anyone trying to convince me to buy. The only time I've even had to say a word back to them was when a friend and I were curious what the street price was so stopped one who offered and said sorry we're not buying, but would you mind telling us the prices, and he did and then went off cheerfully.

I have no idea if this is an accurate depiction, but there's an impression of what snorting heroin as if it were cocaine looks like in Pulp Fiction.

It's significantly more likely that the 'White Heroin' is actually Fentanyl or another designer opioid.