One of the speakers on our conference Psychedelic Lessons 2018 is Fernando Caudevilla, also known as DoctorX. We bring you the English version of interview originally published by Miloš Krekovič in Denník N on May 12th, 2018.

Fernando Caudevilla (Madrid, 1974) is Family Physician and Universitary Expert in Drug Dependence and Medical Assesor of the Spanish NGO Energy Control. He works in a Public Primary Care Center in Madrid and also in different research, education and divulgation projects about risk reduction in recreational drug use, therapeutic cannabis and new psychoactive substances. Known as “DoctorX” in Deep Web, he runs an on-line health service for drug users in a harm reduction perspective in different cryptomarkets (Silk Road, Silk Road 2.0, Evolution Marketplace, DNMAvengers…) from 2011. He is in charge of projects related to International Project: International Energy Control.

When did you became known as Doctor X? How did it happen?

I have been working as a volunteer for the Spanish NGO Energy Control (ABD) since 1999, focused in harm reduction for recreational drug users. I have been involved in different projects but I am very interested in the possibilities that Internet offers to give on-line advice to drug users. It has many advantages (speed, low cost, privacy…) but also limitations (the information you receive through an e-mail is very limited and it can never replace a face-to-face evaluation). But the fact is that many drug users prefer to ask a doctor they do not know in an Internet forum instead of visiting his doctor. I think this is related with the moral prejudices against users of some psychoactives and health professsionals should think about this.

I used my real name in Internet the first years, but my colleagues of Energy Control gave me the nickname of DoctorX, in relation with my interest on MDMA. I liked the name, it sounds like a Superhero , so I became „DoctorX“ in Internet.

What was your first advice?

I started offering health advice about drugs in a harm reduction perspective by 2001 in the Spanish forums of Energy Control. I think the first discussion I participated in talked about the (supposed) efficacy of some supplements (tryptophan, fluoxetine…) in diminishing MDMA hangover.

In Silk Road Marketplace forum I think the first question I was asked is „What is the most dangerous drug is and why“

What was darkweb like when you started there in 2011?

Well…I do not like the word „darkweb“…it sounds like something dangerous and creepy. Deep Web was (and is) similar to the Internet of 1995: a space with total freedom of speech and no censorship. It is important to remember that Tor Browser (the tool used to access Deep Web) was developed during the 90s by United States Naval Research Laboratory employees and financed by US government to protect intelligence communications online. Deep Web helps to avoid censorship in Internet in countries with restricted access to the Web, and facilitates the work of many journalists, activists and politicians. Deep Web is just a tool , that can be used with good or bad purposes but not intrinsecally “evil”or “dark”.

How did the web drug market change since then?
In 2011 Silk Road was the biggest cryptomarket available with two minor competitors. After Silk Road was shut down in October 2011 by FBI , vendors reallocated in new markets in few weeks. In this highly competitive scene, cryptomarkets have developed and nowadays are more user friendly interfaces, offer more options, accept different cryptocurrencies…They have multiplied in number and activity.

How many advices did you give? Considering a number of people taking drugs is it not only drop in the bucket?

In my activity in cryptomarket forums between April 2013 and February 2015 I answered a total of 1146 questions. 931 were published in public forums and received a total of 136.407 visits. I don’t say that is only a drop. (1). A summary of most relevant question is published also (2) and it receives hundreds of visits each week. I am not sure that many “classical prevention” resources have such an impact.

What is the most frequent question people use to ask?

Most common categories are drug efects, patterns of use, dosage, adverse efects, medical contraindications, pharmacological interactions with prescription drugs, pharmacological interactions with other illicit drugs, patterns for detoxification, therapeutic use of cannabis, neurotoxicity, long-term efects of drugs, urine detection of drugs, use of drugs during pregnancy and lactation.

How did you manage to build trust online?

That was the easiest part. I registered in cryptomarket fora with my nickname but also with my personal webpage ( and provided relevant info about my identity and work.

Did you solve a situation, which was so dangerous, that you had a feeling – yes, this makes a perfect sense?

I provide you relevant examples in pages from (1) and in slides 11-13 of (3). This last is particularly shocking and commented in audio.

As Doctor X you are a volunteer. Did some users finance you?

It started as a volunteer. In my thread I offered a Bitcoin address for donations. As my service gained popularity and I spent several hours a day answering questions, annonymous donations became more common. I am not a cryptomillonaire, I still wake up at 7.00 to go to work and live in a 45 m2 apartment. But it is true that many users supported my work with generous donations.

Fernando Caudevilla. Photo – archive of F. C.

In one interview you said, that „web drug markets are more trustworthy than many politicians and wall street businessman,“ What did you mean by that?

In my opinion, an amazing aspect of Silk Road, that has been copied in all existing cryptomarkets, is that are systems based in trust. Both drug vendors and buyers are generally perceived as untrustworthy or scammers but cryptomarkets have proved that this is not true.
Users confide that vendors will deliver their products. Vendors trust that users will pay them (many markets work with a “escrow” system, where money is deposited by user in the market when the product is purchased and in transfered to the vendor when the user receives the product at home). And this system has worked perfectly and is a key point for success of cryptomarkets.
It is also true that scams and exit frauds have been common in Deep Web. Greedy of some administrators (that close the market and dissapear with the money of users and vendors) has been more effective than Law Enforcement actions in control this phenomenon. Not all vendors, buyers or cryptomarkets administrators are honest… and not all politicians or businessmen are corrupt.

Are cryptomarkets safer place as streets for buying drugs? Do you see some positives of darkweb?

This is a matter of discussion in professional and academical research about cryptomarkets. On the one hand cryptomarkets avoid direct contact between users and vendors, and this is a protection factor against crime and violence related to narcotraffic. Markets are highly competitive and, in general, purities are higher and prices are lower than in the streets. On the other hand cryptomarkets provide easy and cheap access to highly addictive or dangerous substances to anyone interested on them and I do not think that is a good idea.

What is the most popular drug people buy online?

There are important regional differences, but according to recent studies cannabis, stimulants and ecstasy were responsible for 70 per cent of all revenues on the analysed cryptomarkets.

What sort of people use to buy drugs online? Do they take them for recreational reasons?

Considering the most common substances purchased, probably many buyers are recreational users. But cryptomarkets offer a wide range of substances and I know cases of heroin addicts receiving their weekly dosage in the mail box instead of purchasing it in a dark corner of the local ghetto. Probably the profile is very heterogeneous.

I heard about drug addicts from Russia searching for heroin subsitutes on darkweb, is it true?

Definitely. Drug Policy in Russia is cruel, inhuman and tantamount to torture. The lack of consideration of Public Health criteria and violation of basic Human Rights is unacceptable. The ban of methadone treatment, difficulties to access to needle and syringe exchange programms explains the highest incidence of HIV, HVC and TBC in the continent.

With this panorama it is not strange that opioid-users from Russia adquire opiates in Deep Web Cryptomarkets. I have adviced to some Russian heroin addicts how to taper-down methadone that they had purchased in cryptomarkets, in order to avoid withdrawal opioid symptoms. This has been considered ethically reprobable by some persons. Considering the circumstances of Russian Drug Policy I have no moral dillema.

Let’s imagine I want buy weed or cocaine online. What I should do to make it as safe as possible? What should I avoid, what can be potencially most dangerous?

First of all, get reliable and objective information about potential risks and harms of the substance and how to reduce risks. You should use a Linux-based computer with TOR and a VPN. Do a lot of search in different markets and forums searching for a reputated vendor. Always encrypt your communications using PGP. Buy only small quantities that can not be considered for traffic. Test your samples in a service as provided by Energy Control International (

What about new dangerous synthetic drugs?

I generally advice against NPS (New Psychoactive Substances). Traditional drugs have been used during centuries (cannabis, opium, cocaine) or have been previously studied as prescription drugs in humans (LSD, MDMA, Ketamine, GHB). But a wide range of synthetic cannabinoids, cathinone derivatives, fentanyl derivatives, arylciclohexamines are being offered in Internet webs just because they are psychoactives although they have never been tested in humans in most cases. This is a extremely dangerous situation and banning of substances is followed by the appearance in the market of a new derivative, chemically more strange than the previous.

This is another example of the schizophrenia of Drug Policy. Cannabis, that is relatively safe, is banned but you can buy synthetic cannabinoids that can kill you with a VISA Card. It is noticeable that countries where natural cannabis is cheap and accesible, the phenomenon of synthetic cannabinoids is very limited.

Do people often blame you for making drugs more popular while doing harm reduction advising?

It is important to spread the information in the adequate context. If I had to talk with a clasroom of 8-year old boys, my messages would be inadequated. But my work is done in an environment of drug users and harm reduction messages are adequate here.

In any case, the idea that “talking about drugs promote use” is the same kind of reasoning that condoms facilitate rampant sex or fire extinguishers cause fire.

Many cryptomarkets were closed since Sillk Road 1 was closed by police in 2013, but many other markets emerged. Do you see this way of restrictions as something succesful?

Definetly not. And this is not a personal opinion. When you submit this question to scientific research two independent studies conclude that is there is no evidence that Law Enforcement activity has a significant impact on this growing phenomenon. Unfortunately, Science, Public Health or Human Rights

What should an ideal drug policy look like? Do you support full legalisation of some substances?

I think there is not a 100% ideal drug policy. During the last century we have been using the same formula that has caused much more problems that these were supposed to solve. Fiscalized substances are easily available and in hands of criminals. I don’t know if they should be controlled by states, private companies, associations, professionals… Tomatoes, tobacco and antibiotics are examples of “full legal products” but have different ways to access. I support “full legalisation” of ALL psychoactives (but that does not necessarily mean that everybody can purchase them everywhere). We have spent the last 100 years with counter-productive Drug Policies based in moral criteria. So we could spend the next 100 essaying different models using scientific criteria and considering Human Rights and Public Health.

Why did you finish with offering advice in cryptomarkets?

Silk Road, the first cryptomarket, was closed by FBI in October 2013. I continued my work in other websites but in 2015 the lawyers of Ross Ulbritch (Dread Pirate Roberts, the alleged mastermind of Silk Road) asked me to testify in the trial. In that moment my work had been published in scientific journals and congresses.
I agreed to do it, I sent an affidavit (6) and all the documentation that the judge asked me, including a copy of all my activity (7). During the sentence,the judge considered me an “enabler”, my behavior “breathtakingly irresponsible.” and “despicable”.(8). I had no access to the complete transcription but I realized that my testimony had been, at least, “misquoted” (9). After the sentence was unsealed, one year after, I would change “misquoted” by “manipulated”.
I prefer not to enter into details, but several factors suggested me that it was the moment to take a rest.

And do you think about going back to work in this way?

Of course I am back. I believe that Harm Reduction is the best strategy to preserve health of drug users. For the last 2 years I have been working in the expansion of Energy Control to an international level. We have launched an International Website ( and we are offering an International Drug Checking Service ( One of our targets is monitoring drug tendences in cryptomarkets and this month we have launched our first report, in which we show the presence of heroin adulterated with fentanyl derivatives in European vendors, a worrying phenomenon unknown until the moment (10). Ah, and this time DoctorX is not alone. My colleagues from laboratory are now “Chemical Brothers and Sisters” and, I think that DoctorX will be able to work better with this fantastic team of psychologist, chemists, biologist and Public Health experts.


(1) Data available in
(4) Décary-Hétu, D. & Giommoni, L. Do police crackdowns disrupt drug cryptomarkets? A longitudinal analysis of the effects of Operation Onymous Crime Law Soc Change (2017) 67: 55.
(5) Van Burskik et al. The recovery of online drug markets following law enforcement and other disruptions. Drug & Alcohol Dependence, 2017 Volume 173, Pages 159–162