Converting Animal Doses to Human Doses (Kratom)

Hint: you can’t just multiply the mg/kg given to a rodent and throw your own body weight in.

I’ve written this article about a million times. Other people have written this article. But with the recent Inverse article covering the newly-discovered LD50 for kratom, it warrants another visit. Simply stated, if a mouse receives 1mg/kg of kratom, and you weigh 100 kilograms, the equivalent dose for you isn’t 100 milligrams. There’s a formula:

Look confusing? Ok, here’s how it breaks down:

So to convert the oral mitragynine LD50 to a human equivalent, we multiply the dose (548mgs) by 3 (because they used mice), then we divide by 37. We end up with 44 milligrams per kilogram.

Dried kratom leaf contains about 1.2–2.1 mitragynine (it is the most abundant alkaloid, at 66%, but we are talking about content by weight, not alkaloid percent). So in a gram of powdered/dried kratom, there exists between 10 and 20 milligrams of mitragynine (no LD50 was discovered for 7-hydroxymitragynine).

So you would need to ingest at least two grams of kratom to arrive (ballpark) at our 44mgs of mitragynine (assuming your kratom is on the high end of mitragynine content) And you’d have to ingest those two grams multiplied by your body weight (in kilograms) to reach the LD50. So if you weigh 100kgs, you would need to ingest 200 grams of powdered kratom. If you’re the average American man (in kilograms) you need 180 grams of kratom to reach the LD50. For women, it’s about 150 grams.

That’s all assuming your kratom has the highest natural levels of mitragynine. If we assume it’s on the lower end, roughly double that figure: men would need 360 grams, women 300 grams. Splitting the difference, assuming average kratom with a medium mitragynine content, men are at 270 grams and women are at 225 grams.

If you’re unfamiliar with kratom and find yourself asking how dangerous or common this actually is, most people take a couple of grams at a time. Heavy use is considered anywhere between 15–20 grams daily.