Toxicology of George's Marvellous Medicine

Just how bad for you is the famous medicine from Roald Dahl's book?
22 December 2020

Interview with 

Graham Johnson, University of Nottingham


A bottle marked with a skull and crossbones, and the word poison, containing a dark purple liquid


In Roald Dahl’s famous book “George’s Marvellous Medicine”, a young boy called George decides to make his grandma less cranky and horrible by replacing her usual medicine with his own invention. His improvised concoction uses items from all over his house, from shampoo and toothpaste, to floor polish, engine oil and antifreeze. When his gran drinks it, she grows as tall as the house, a result that real-world paediatric doctors Graham Johnson and Patrick Davies decided needed checking. And so, helped by their own kids, they’ve analysed George’s recipe, as Graham explained to Phil Sansom…

Graham - He wasn't quite as scientific as we would have liked him to have been. He didn't write it down. And that means he comes a bit unstuck when grandma becomes really invigorated and grows enormous. And his father is really excited by that because he thinks, "Oh, wow, we can make a lot of money out of this." And because he hasn't been systematic and noted everything down, medicines two, three, and four have very, very different effects.

Phil - Right. Obviously we frown on that kind of process, not scientific. So what's the right way to do it? What did you do?

Graham - We employed five very junior researchers.

Phil - How junior?

Graham - Well, the youngest was seven and didn't have his school pen license at the time. They worked in three different groups, and they went through the book, writing down every single ingredient. Then we compared those groups. So there's three independent groups that they were in. We made sure that all their results were the same, which they were, and went to the national poisons information service website called TOXBASE, and looked up all the different ingredients, and what possible toxic effects that they would give.

Phil - All sounds very rigorous, all sounds very above board.

Graham - I'd like to think so.

Phil - What did you find?

Graham - Uh.

Phil - You're making noises that make it sound not good!

Graham - There was quite a lot to find. So, basically grandma would not have been very well at all. Actually some of Roald Dahl's descriptions were really accurate. So she talks about how her stomach's on fire. There are lots of ingredients that might cause indigestion, or nausea, and vomiting, and gastric ulcers, and things, sheep dip in there, and shoe polish. She starts to swell and there were a few ingredients in there that might cause some foaming in particular in there, in that things like the shampoo. Then there's, she has this sudden sharp twist and jerk and flips herself out of the chair. There were several ingredients that would cause convulsions. But from there, she starts to grow, and she becomes invigorated, and she bursts through the roof of the house. That's not really what would have happened, unfortunately. There are several ingredients in there that would make her very sleepy. In addition to the convulsions, she might have stopped breathing, developed kidney failure. There were several ingredients that would cause vomiting. And then these erosions in her oesophagus, and maybe through to her aorta and all sorts, you'd have been in a right mess.

Phil - This is not looking good for grandma.

Graham - Not at all.

Phil - What do you predict would have happened to her?

Graham - It is highly unlikely that she would have survived such a toxicological insult.

Phil - It's interesting. Because it's very different from the results reported in the book.

Graham - It is.

Phil - I'm just wondering maybe, are there some interactions maybe that you don't have in your database, something like that, that make a person become giant?

Graham - Yeah, that's possible. I mean, we weren't able to reproduce the singing and the chanting, and obviously we are just extrapolating from known results, and we haven't recreated making this medicine.

Phil - It's not really a way around that is there?

Graham - Not so much. No.

Phil - If I want to tinker with the recipe myself, what do I have to do? Do I have to go through the rigmarole of what you did, and go through the database or do I have to make one or what?

Graham - Well, we've tried to make this easier for you, or the BMJ have. So if you go to the and look for George's Marvellous Medicine and our paper is there, they have made a simulator so that you can mix all the different ingredients from around the house, and see how poorly that they would make you. And there are some little Easter eggs in there as well, that are not on the achievements board. So please go and have a look at that and have a play.

Phil - If I unlock any of those Easter eggs, do I become an honorary marvellous medical doctor?

Graham - Absolutely. I would be delighted if you tweeted both me and Patrick Davies, if you managed to unlock one of the three Easter eggs, you'll know that you've found one because I'll give you a little clue, a chicken appears, a certain chicken. So please tweet me if you managed to find out one of those.


Add a comment