Number Needed To Treat

In March, news came out that LSD was an effective way to treat alcoholism. (The thinking is that the profound hallucinogenic experience changes one’s view of the world, kind of like a spiritual awakening. Hallucinogenics have been shown to also reduce the rate at which criminals return to crime.) But how effective is LSD as an alcoholism treatment? The answer is 6.

That’s a measure called Number Needed To Treat (NNT), and it’s the number of people that will statistically be treated in order for one person to benefit from the treatment. So if 6 drunks are treated with LSD, 1 will give up the bottle. That works out to about 16% effectiveness, which means 84% of alcoholics would take LSD and the only thing they would get out of it is a psychedelic trip.

LSD is a highly-concentrated liquid, commonly distributed on the backs of stamps which are then placed on the tongue for absorption


Sounds like pretty meager results, but it turns out that medicine is a pretty poor science, and 16% effectiveness is actually pretty high. Things are so bad, that if the NNT is below 10 — that’s benefits for just 1 in 10 patients, or 10% effectiveness — that’s considered a very successful drug or treatment. Keeping in mind that an NNT of 1 means everyone treated will benefit and that the higher the number, the less effective the treatment, here are the NNT numbers for some well-known treatments:

A related measure is the Number Needed To Harm (NNH), which is complementary to the NNT. For example, the drug Vioxx had a great NNT of 2.2, but it’s NNH of 42 was a little too low for comfort, so it was pulled from the market. The moral of the story: find out the NNT and NNH of the drugs and treatments you’re prescribed.

In the meantime, LSD is still classified in the “most dangerous drugs” category by the UN and US, along with drugs like heroin and cocaine. This, in spite of the fact that LSD has yet to cause a single death, which is more than can be said about many legal drugs, like Vioxx. In fact, LSD is a fairly safe drug and was only banned as a backlash to its use by the counterculture of the 1960s, and in particular, by its leading proponent, Harvard psychologist Dr. Timothy Leary. The graphic above shows a rating of common legal and illegal drugs done in 2007 by a team of scientists; the drugs are ranked by how much harm they have the potential to do to society: LSD was on par with Ritalin, and both were well below alcohol and tobacco.

And below, a very interesting video of a 1950s housewife tripping on acid in a clinical setting at the Veteran’s Administration, back when it was legal.

See also:


From NPR


  1. Medical-Grade Ecstasy Is Perfectly Safe | Apt46 - pingback on June 15, 2012 at 8:42 pm

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