LD50 of Cannabis

The estimated LD-50 (lethal threshold) for marijuana,established in 1988 by the DEA’s appropriate fact-finder, is 1:20,000 or 1:40,000.


At present it is estimated that marijuana’s LD-50 is around1:20,000 or 1:40,000. In layman terms this means that in order to induce death a marijuana smoker would have to consume 20,000 to 40,000 times as much marijuana as is contained in one marijuana cigarette. NIDA-supplied marijuana cigarettes weigh approximately .9 grams. A smoker would theoretically have to consume nearly 1,500 pounds of marijuana within about fifteen minutes to induce a lethal response.


Page 1

Note: In Judge Young’s report cannabis is referred to as marijuana

Drug Enforcement Administration
In The Matter Of
Docket No. 86-22
Administrative LAW JUDGE.
FRANCIS L. YOUNG, Administrative Law Judge
DATED: SEP 6 1988

FRANCIS L. YOUNG, Administrative Law Judge


Part VIII.


With respect to whether or not there is “a lack of accepted safety
for use of [marijuana] under medical supervision”, the record shows the
following facts to be uncontroverted.

Findings of Fact

Point 3. The most obvious concern when dealing with drug
safety is the possibility of lethal effects. Can the drug
cause death?
4. Nearly all medicines have toxic, potentially lethal
effects. But marijuana is not such a substance. There is no
record in the extensive medical literature describing a
proven, documented cannabis-induced fatality.
5. This is a remarkable statement. First, the record on
marijuana encompasses 5,000 years of human experience.
Second, marijuana is now used daily by enormous numbers of
people throughout the world. Estimates suggest that from
twenty million to fifty million Americans routinely, albeit
illegally, smoke marijuana without the benefit of direct
medical supervision. Yet, despite this long history of use

Page 2

and the extraordinarily high numbers of social smokers,
there are simply no credible medical reports to suggest
that consuming marijuana has caused a single death.
6. By contrast aspirin, a commonly used, over-the-counter
medicine, causes hundreds of deaths each year.
7. Drugs used in medicine are routinely given what is
called an LD-50. The LD-50 rating indicates at what dosage
fifty percent of test animals receiving a drug will die as
a result of drug induced toxicity. A number of researchers
have attempted to determine marijuana’s LD-50 rating in
test animals, without success. Simply stated, researchers
have been unable to give animals enough marijuana to induce
8. At present it is estimated that marijuana’s LD-50 is
1:20,000 or 1:40,000. In layman terms this means that in
order to induce death a marijuana smoker would have to
consume 20,000 to 40,000 times as much marijuana as is
contained in onemarijuana cigarette. NIDA-supplied
marijuana cigarettes weigh approximately .9 grams. A smoker
would theoretically have to consume nearly 1,500 pounds of
marijuana within about fifteen minutes to induce a lethal
9. In practical terms, marijuana cannot induce a lethal
response as a result of drug-related toxicity.
10. Another common medical way to determine drug safety is
called the therapeutic ratio. This ratio defines the
difference between a therapeutically effective dose and a
dose which is capable of inducing adverse effects.
11. A commonly used over-the-counter product like aspirin
has a therapeutic ratio of around 1:20. Two aspirins are
the recommended dose for adult patients. Twenty times this
dose, forty aspirins, may cause a lethal reaction in some
patients, and will almost certainly cause gross injury to
the digestive system, including extensive internal
12. The therapeutic ratio for prescribed drugs is commonly
around 1:10 or lower. Valium, a commonly used prescriptive
drug, may cause very serious biological damage if patients
use ten times the recommended (therapeutic) dose.
13. There are, of course, prescriptive drugs which have
much lower therapeutic ratios. Many of the drugs used to
treat patients with cancer, glaucoma and multiple sclerosis
are highly toxic. The therapeutic ratio of some of the
drugs used in antineoplastic therapies, for example, are
regarded as extremely toxic poisons with therapeutic ratios

Page 3

that may fall below 1:1.5. These drugs also have very low
LD-50 ratios and can result in toxic, even lethal
reactions, while being properly employed.
14. By contrast, marijuana’s therapeutic ratio, like its
LD-50, is impossible to quantify because it is so high.
15. In strict medical terms marijuana is far safer than
many foods we commonly consume. For example, eating ten raw
potatoes can result in a toxic response. By comparison, it
is physically impossible to eat enough marijuana to induce
16. Marijuana, in its natural form, is one of the safest
therapeutically active substances known to man. By any
measure of rational analysis marijuana can be safely used
within a supervised routine of medical care.”



20 thoughts on “LD50 of Cannabis

  1. The only way to kill a rat with an LD50 test on marijuana is to get a big, big lump of resin and beat the poor animal to death with it ! I speak as a Pest Controller and a medical smoker, so I know abit about toxic substances and Rats!

    Posted by Rat King | July 14, 2013, 3:17 pm
    • Why do you smoke weed with the rats? Marihauna made my son commint double homicide. My older sister, bless her heart, died from smoking an entire bag of weed in a night. Marihauna is the devil’s invention. So you smoke your marihauna and get marihauna poisoning.

      Posted by Concerned parent | September 15, 2015, 9:02 pm
      • Marijuana does not affect the the heart or the respiratory system as they do not have cannabanoid receptors. It actually protects the brain by blocking access to new brain cells (thats why the short memory does not function, although this is just temporary).

        So you are either confused with another drug or you are full of shit.

        Concerned parent my @$$

        Posted by John | December 19, 2015, 3:53 am
      • You are so full of bovine excrement we can smell it over the internet.

        First, Marijuana did not MAKE your son do anything (he was a good boy, didn’t do nuttn, I know). He may have murdered someone FOR marijuana making the little angel a thief on top of a murderer. But weed didn’t MAKE him do it. Shitty culture may have encouraged it as well as other truly awful drugs.
        Pot moves people to lovers not fighters. You may call bs but I was there so suck it. (for all legal purposes this is a work of fiction). I arrived at a bar for a little social hour, Friday evening, 9ish. Took a bar seat and ordered a drink. Just finished a first sip. There were about 12 people in the bar. This guy (linebacker beefcake high test in need of a little cut darker than walnut and just as hard) walked up and wanted to start something because I was in his seat. “get the f%&* out of my seat” “come on you pinche (I live close to Mexico) cracker, get the f%^* up” “come on, outside now” (Oh crap, I f’ed up. Went to the wrong bar and now Jack Tatum look alike is going to wad me up). I got up and at a light pace made my way to the patio as I thought that was better than fully outside. As I crossed the threshold to the patio I removed and lit the dube in my cap, sparked it and took a long drag as I turned and handed it to the bastard. It was a big cone and it took 10-15 minutes of puff puff pass, all in silence to ash it out. … … …Me: “You ready for a drink?” him: “yeah, just another minute” me: “okay”.

        Second, there are four options that would cause your daughter to die from smoking “an entire bag of weed in a night”. First, the bag somehow got stuck over her head and being stupid or to ignorant to remove it (look at her brother and Concerned Parent, intelligence isn’t a theme in your family) was unable to find her way out and asphyxiated. Second, still related to her upbringing or education, she aspirated the bag and choked on it internally. Third, someone beat her to death for smoking their “ENTIRE BAG OF WEED IN A NIGHT”, least likely option. Fourth, If her bag contained 1,500 POUNDS and she smoked it by herself in 15 MINUTES she would have hit the LD50 dose where half of subjects would die. That’s not a bag, It is about 100 30 gallon rubber made containers of weed. While there are some that will smoke a 1/4 bag in a night (7 grams) they are usually wasting over half as many smokers mention a plateau where they just can’t get any higher no matter how much they smoke. The body only has so many receptors and once they are satruated you may be high longer but there is a point you peak out. Another “true story”, wax, oil, shatter, is refined THC, 70-90% THC, 5-10 times more pure than flower. A gram was packed into pipe, that’s equivalent to 5-10 grams of flower (a good sized bag). There was nothing to light it with so an industrial soldering iron at 650 F was resourced. One expected to smoke 20 or so drags out of the pipe over the next week. To my surprise 650 degrees on a large K tip iron vaporized the entire bowl nearly instantly in the first 2 seconds of the drag. That’s 14-20 joints in 2 seconds. Was it pleasant, no. Felt like someone had kicked a hornets nest in my chest and I barely made it the 4 steps from my bathroom to my bed. Did I die? No. Get sick? No. hang over, no. kill anyone, no. Rape, steal, cheat, abuse, no, no, no, no. Cough till I blew snot out of my nose for 5 minutes, yes.

        Third, “Marihauna is the devil’s invention”. First I thought you were ignorant, now… wow, how do you get your pants on in the morning? Gen 1:12 The land produced vegetation: plants bearing seed according to their kinds and trees bearing fruit with seed in it according to their kinds. And God saw that it was good. Gen 1:29 Then God said, “I give you every seed-bearing plant on the face of the whole earth and every tree that has fruit with seed in it. They will be yours for food. Isaiah 18:4-5 4 For so the Lord said unto me, I will take my rest, and I will consider in my dwelling place like a clear heat upon herbs, and like a cloud of dew in the heat of harvest. 5 For afore the harvest, when the bud is perfect, and the sour grape is ripening in the flower, he shall both cut off the sprigs with pruning hooks, and take away and cut down the branches. Mat 15:11 The apostle Paul wrote, I know, and am persuaded by the Lord Jesus, that there is nothing unclean of itself: but to him that esteemeth anything to be unclean, to him it is unclean (it is unclean to you because you esteem to to be, but it is only to you that it is unclean. You can’t make it unclean to me because you don’t like it. I know, I like something you don’t like, I must be evil.

        I mean, oh my god. 10s of thousands die from alcohol every year, hundreds die from aspirin, eating 10 raw potatoes is more dangerous than smoking a pounds worth of pot in a day. You might be stoned for a week but you wont get sick or die.

        Posted by Twoyearsoldbutihopeyoureadthis | August 18, 2017, 1:42 am
      • Dear Concerned Parent. I am deeply sorry for your loss. nobody should experience anything like that. I am also a concerned parent – but I know for a fact that no one wakes up one day, smokes a bag of weed, gets a psychosis and decides to go on a murdering rampage. Every story has got their untold side stories – and even if he was your nice boy – perhaps you should have asked him, why he went out on a killing spree. I can only say weed doesnt kill people. – people kill people. If all drugs were legal and if the states who sell guns to people, earning money on selling guns – while fighting drugs in a so-called drug war with weapons they made tax money with while selling those guns to the drug king pins – would put all the tax money they would receive out of the legalisation of drugs and put it into educational systems where people would be wise enough to not try everything they may do, than we would not be having the problems, we are having right now. Most likely your kid might have known her limits and your boy might have known that guns do no good to people.

        Posted by cannabiphil | May 21, 2018, 12:03 pm
  2. The federal government estimates the death toll of tobacco is 480,000 per year.

    Posted by Lynn Dorn | April 9, 2014, 3:44 pm
  3. The LD-50 tests I’ve seen all seem to focus on the amount of cannabis that must be smoked. Obviously, the body would simply pass out long before anything even remotely close to an LD-50 point was reached.

    But what about eating it in a concentrated form – say, in the form of hashish or hash oil? A huge amount of either of those could theoretically be ingested before their effects made continuing impossible.

    Posted by Etienne Regaj | September 30, 2015, 11:33 am
    • Hash oil can only be made to a maximum of 100% THC, whereas good marijuana is typically around 25%. So you would still have to ingest 375 pounds of 100% pure THC oil to reach the toxicity point. I don’t know about you but if I ingested 375 pounds of anything in 15 minutes I would die. Do some research people.

      Posted by Hunter Baker | February 19, 2016, 4:34 pm
      • Don’t forget you would have to buy that much and Idk about you but 375lbs of concentrates is far beyond most peoples ability to purchase at once XD

        Posted by Sean LeBlanc | September 30, 2017, 7:36 pm
      • Sorry to correct you here, Hunter Baker. THC is a crystal and not an oil. If you have an oil it is always a solution

        Posted by cannabiphil | May 21, 2018, 11:49 am
  4. 40,000 (large estimate for LD-50) x .9 grams (normal 15 minute dose) = 79 pounds (not 1500 pounds as claimed). It would still be a physical impossibility to achieve an overdose.

    Posted by Christopher H. Lawson | May 18, 2016, 9:53 am
  5. The LD-50 ratio is 40000:1. 40000 x the standard dose (.9 grams) = 36000 grams = 36 kilograms = 79.2 pounds.
    This is still impossible to consume within fifteen minutes but it is NOT “nearly 1,500 pounds”. Young’s math is wrong.

    Posted by Christopher H. Lawson | May 19, 2016, 6:19 am
  6. My back of the envelope calculations using .2 gm 100%THC as a base dose* yield 4-8 Kilograms as the LD50.

    Still and impossible amount to ingest, it would begin to make you physically(mechanically) ill trying.

    *5 people on a 1 gm bowl (20%THC) vs. the studies 1 person

    Posted by Charles Barnard | September 20, 2017, 2:27 pm
  7. I am quite sad they just assumed and pretty much helped perpetuate a rumor/troll….

    Posted by Virgil Mihalkovic | January 3, 2018, 1:17 pm
  8. So THC is not toxic, at least not really…

    Best regards from Switzerland,

    Posted by Sara Hofmann | May 20, 2018, 7:18 am


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