Medical content in The Substance (SPOILERS)

(SPOILERS FOR THE WHOLE MOVIE)

I just recently watched The Substance, and I really enjoyed it, but something that rubbed me the wrong way was the medical content. I didn't really expect any of the medical stuff to be accurate- in TV/films it rarely if ever is- but what shocked me was the absolute lack of instruction that came with The Substance.

So i want to be clear- this isn't really a complaint about medical inaccuracy, this is me wondering out loud what's going on and if these artistic decisions were intentional (I assume they were) and what they mean.

There's a lot of mystery surrounding The Substance. You don't know who makes it, you never pay for it, you don't even know what it is, you just get notified to go pick up your supplies whenever they're ready. And I assume after you've been using for awhile you just know the drill, but when you're first starting, how the FUCK are you supposed to know what to do with any of the stuff?

The instructions are SO minimal. There's a starter kit. There are cards that say "you stabilize every day, you switch every 7 days, remember you are one". That's it. They give you a vial and a needle that says "discard after use". They don't tell you where to inject it, whether it's supposed to be intravenous or intramuscular, etc. How does Elisabeth know to inject the starter into her veins? I suppose because it came with a tourniquet?

They don't explain stabilization, they just give you a needle that looks like it's for drawing cerebral spinal fluid and 7 days of vials. How is Sue supposed to know how to draw CSF, how much of it to draw, and where to inject it? It looks like she is successful every time- she has no problem drawing and injecting into her muscle (which makes no sense but that's fine), but my problem is how did she know to do that?

The food package labeling also bothered me. Let's set aside for a second that it seems unclear whether that should be IV or feeding tube food, the labels are "food matrix" and "food other self". How are you supposed to know which one is for you??? Like which one is you and which one is your "other self"? Elisabeth and Sue seemed to just know. Perhaps the food bags are identical and it doesn't matter which you use for who, but what if they weren't??

I know this sounds nit picky, but it looks to me like the rest of the movie is VERY meticulously thought out, so I'm sure it's not just "we didn't pay attention to the science details, we just threw it together". I wanna know how the girls were just supposed to know what to do with The Substance and what that means in the greater context of the film. Like is it a metaphor for women just knowing what they need to do to be beautiful for society without really needing to be told?

Like, everything else is very intentional. The way Sue treats Elisabeth's body with absolutely no respect, and even with disgust from the very beginning. All intentional. So what is the meaning behind the substance having no instructions, being free, etc?

I get the meaning behind the half door- you go to great lengths for beauty. I see the meaning behind technically having the choice but feeling like you're not able to stop. I'm wondering what the other pieces are here that I'm missing