How Dangerous Are Illegal Drugs?

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It's time to get things straight in the crooked world of illegal drugs. As a parent of a son who occasionally experiments with illegal substances such as marijuana and "ecstasy," I fear most two events: (1) a phone call from a hospital emergency room saying that he is dead or dying, and (2) his becoming addicted to a drug that ruins his career, relationships, and health.

These personal fears prompted me eight years ago, quite naively at it turns out, to find out which psychoactive drugs were the "most dangerous." As with many topics, things get complicated really fast when you start looking at them carefully.

For example, a drug's lethality must be estimated from non-human animal studies (where the generalization to human beings is always problematic) and on reports of human fatalities (where the amount and exact composition of the substance ingested is often unknown). At least with lethality, you have a corpse. However, when it comes to addiction, the concept itself is open to interpretation. We can define "addiction" as "physical dependence" (the existence of withdrawal symptoms) or as "psychological dependence" (the habit-forming effects of euphoric experiences) or as the "capture ratio" (the percentage of people who try the substance then later find that they have difficulty controlling its use despite negative consequences). Different definitions get different results. With respect to "physical dependence," for example, alcohol would be ranked near the top; but with respect to the "capture ratio," alcohol would be fairly low. Compare this to cocaine which comes in near the top of "psychological dependence," but has relatively low "physical dependence."

Such complexities should temper anyone's dogmatism. Here, as best I can determine, is a summary of the relative risk of acute lethality of twenty-five psychoactive substances, along with an estimate of their addiction potential. Note that the route of administration is a critical factor in determining risk, and also that individual users vary in their vulnerability to death or addiction.

Acute Lethality Addiction Potential
Alcohol (oral) Moderate/high High
Aspirin (oral) Moderate Low
Caffeine (oral) Low Moderate/low
Cocaine (intranasal) Moderate/high Moderate/high
Codeine (oral) Moderate Moderate
Dextromethorphan (oral) High Moderate/low
"Ecstasy" (methylenedioxymethamphetamine) (oral) Moderate Moderate/low
GHB (gamma-hydroxybutyric acid) (oral) Moderate/high Moderate/low
Heroin (intravenous) High Very high
Isobutyl nitrite ("poppers") Moderate/high Moderate
Kava kava Moderate/low Moderate/low
Ketamine (inhaled) Moderate/high Moderate/high
LSD (oral) Low Very low
Marijuana (smoked) Very low Low/moderate
Mescaline (oral) Moderate/high Very low
Methamphetamine (inhaled) Moderate/high Very high
Morphine (oral) Moderate High
Nicotine (smoked) Moderate High
Nitrous oxide (inhaled) Low Moderate/high
Nutmeg (oral) High Low
Opium (smoked) Moderate/high Very high
Prozac (fluoxetine) (oral) Low Moderate/low
Psilocybin ("magic mushrooms") (oral) Low Very low
Ritalin (methylphenidate) (oral) Low Moderate
St. John's Wort (hypericin) (oral) Low Low

An inconvenient conclusion is that alcohol, codeine, and nicotine are more toxic and addicting than LSD or marijuana. Because all drugs and foods are hazardous to some degree, one's task is not to avoid every risk but to "invest" risks so that one gets the most satisfying benefits for the least probable costs. At the present time, many young people are using the more dangerous drugs such as cocaine for recreational purposes, which seems unwise, while older people often use many drugs with proven side effects while avoiding less dangerous drugs such as psilocybin ("magic mushrooms"). Neither drug users nor elected officials seem aware of the "risk economics" of the dozens of psychoactive substances that percolate through our schools, streets, pharmacies, and homes. Some sober brains should get to work on this problem.

Robert Gable, J.D., Ph.D., is a psychology professor at Claremont Graduate University


February 27, 2002

The sentence introducing the table of psychoactive drugs and their effects implies that aspirin has psychoactive effects is that actually true? If so, I think it's not well known and should perhaps be explained briefly.

R.M. Barr

Gable responds:

The reader asks a legitimate question. Aspirin and other substances such as acetaminophen (Tylenol) are included in the federal government's annual Drug Abuse Warning Network survey. The Feds include aspirin, along with other substances having "psychic effects," because the substances improve mental states including the reduction of pain, relieving headache, and getting to sleep. These are indeed not the more spectacular effects that we usually associate with psychoactive substances.

My primary reason for including aspirin (and also coffee/caffeine) in the list was to provide a popular, common reference for the various toxicities. In the year 2000, there were over 15,000 emergency department visits in which aspirin was involved.

Robert Gable, Psychology Department, Claremont University

March 12, 2002

A very interesting article with some not so very new conclusions. Without this study most of us can use common sense to sort the "men from the boys" as far as recreational drugs are concerned, and some of us have already done so. Especially those of us in constant pain on a drug regime that affects almost every part of our being, reducing appetite, causing dizziness, and a whole list of other symptoms which make us undesirable in the workplace or behind the wheel of a car.

It is obvious to me as an arachnoiditis sufferer that my prescription drugs carry some very hairy and unfortunate side affects addiction being one, lethality being another. We know that the relief we get from the unprescribed drug "Marijuana (smoked)" [as a chart in Gable's article called it] is sometimes much better than dihydrocodeine or any of the other opiates, and is much safer which this article underlines. It also boosts our lost appetites, which means we are well nourished and, as such, better placed to fight our daily bouts of pain.

If the figures were ever calculated, they would probably show I am more likely to die of liver failure because of my prescription drugs than I am to die from smoking marijuana. If I was able to obtain marijuana on prescription, in the form of tablets with the hallucinogens taken out, then the great remaining risk, cancer, would not be there at all and I might be able to get back to work.

Here in the UK, police are discouraged from pursuing individuals who are carrying marijuana for their own use or smoking it on their own premises. This is not folly, as some bigoted non-thinkers would have us believe; it is plain common sense, and the sooner that is realised worldwide the better.

Robert Gable's article underlines all that I claim and should be waved under the noses of law enforcement officers who think that catching anybody with the drug on them creates another gold star on their records. Leave these individuals alone. Legalise cannabis and marijuana and, to the chagrin of all those who currently shout such theories down, violent offences will fall.

I would never encourage the use of any of the harder drugs in anything other than a medical setting and I cheer on the efforts of those guys in blue all over the world who are trying to jail the thugs who peddle them. If we take the restrictions away from the softer drugs, the sellers of hard drugs would almost certainly have to find other markets for their products. Across-the-counter sales of their former gateway product would also cut out a great deal of their market share because they could no longer use it as a lever to get people to try stronger substances. Legalisation would also cut their routes of communication to our kids, wherever we live.

The police, with less to worry about, would also have more time on their hands to fight the battle against the stronger substances and the thugs and parasites who peddle them.

Mike Feehan

August 15, 2002

I too am curious about the table. I'm surprised to find alcohol listed as having moderate to high acute lethality and nutmeg as having high acute lethality. How are these levels defined? I would think they should be defined either in terms of the ratio of lethal dose to effective dose, or in terms of the incidence of acute lethality in relation to use.

An effective dose of alcohol is two to four drinks, at which point the subject is more or less pleasantly high. The lethal dose must be at least five to ten times as much; does that constitute moderate to high lethality? And nutmeg has a pretty strong taste, so I doubt that anybody seeking a gustatorily-effective dose of nutmeg would use enough to kill.

As for the incidence of acute lethality, the chronic effects of excessive alcohol use are well known, but I don't often hear of acute alcohol lethality, considering the number of people who use alcohol. And I have never heard of death from acute nutmeg poisoning.

So how were the gradations of acute lethality determined?

By the same token, what were the criteria for grading addiction potential? The word "potential" suggests "capture ratio" rather than "physical dependence" or "psychological dependence" (to use the author's terminology). But then why is alcohol rated high in addiction potential when the author cited it as having a low capture ratio?

Alternatively, addiction potential might be defined as the probability that a user, once started at a low level, might still be using and unable to stop a few months or years later. That would be a composite of capture ratio and the two aspects of dependence. But then alcohol should be rated low to moderate, rather than high, because of its low capture ratio. In fact, for each addicted alcoholic, there are many, many people (like me) who use alcohol in moderation and can stop whenever they have a reason to.

So, how were the gradations of addiction potential determined?

Martin B. Brilliant
Holmdel, NJ

January 9, 2004

An interesting article. The only comment I have is about lethality and less serious "harm" from drugs. In your discussion, it appears that you have only included physical damage. Surely psychological damage is very likely, particularly from apparently harmless (by your categorization) drugs like LSD and cannabis (a link between this drug and schizophrenia has been proven). I have never been convinced of the vector, that is, that drugs cause psychological problems. I would always say that drugs are taken because someone has psychological problems.

David Scott