I tried to CTB with antifreeze in 2021. Here's my experience.
First thing to know: they add a "bittering agent" to stop kids and pets from drinking it. It tastes absolutely vile. Words can't describe how disgusting it is. I drank bleach as a teenager, and I can tell you antifreeze tastes worse. It's thick, toxic, and metallic... imagine drinking petrol.
I managed to down about a cup before I started vomiting it up again, from sheer physical revulsion.
So I asked myself "how can I get more of this into my body without triggering my gag reflex?" Luckily I used to be a heroin addict, so I had hypodermic needles in my closet, and I know how to IV inject. I filled up half a dozen syringes with antifreeze and injected them all. It felt like a cold burning in my veins. Very painful. After that I tried drinking it again. I mixed it with Monster Mango Loco to disguise the taste (it didn't work) and took small sips. Gagged a few times but no vomiting. Overall I couldn't tell you how much I ingested.
By this point I was super dizzy (it feels like being extremely drunk) and after about 5 minutes I was hit by an urgent, overwhelming feeling of dread and panic. Probably psychological. I suddenly and inexplicably decided I didn't want to die inside my apartment, so I went for a walk to a nearby park. It was night-time so I hoped I would fall asleep in the bushes and my body would be found in the morning.
Last thing I remember is staggering along a footpath feeling like I'd drank a whole bottle of vodka. Then I was in the ICU, hooked up to all sorts of medical equipment. They told me I'd lost consciousness and a member of the public called an ambulance.
Here's where it gets weird: the nurses brought me a bottle of Jack Daniels (with the label removed) and made me drink 6 shots in a row. Turns out the antidote to ethylene glycol (antifreeze) poisoning is ethanol, and the easiest way to get ethanol into the body is to drink hard liquor.
An hour later, they made me drink 2 more shots. An hour later, another 2. They made me drink shots every hour... hour after hour after hour. They'd wake me up during the night, every hour, to drink another shot. This went on for days.
They gave me alcohol poisoning to treat the ethylene glycol poisoning, then kept me alive by treating the symptoms of the alcohol poisoning.
They pumped me full of thiamine (and god knows what else) to protect my liver from the crazy amount of alcohol they were giving me. They gave me a constant supply of anti-convulsants, anti-emetics, heart medications, and naltrexone. Eventually, they intubated me and switched to intravenous ethanol.
While intubated, I was mostly unconscious, drifting in and out. Even once I sobered up and the tube was removed, I was delirious for days. Not sure why. Possibly the antifreeze itself was still in my system. My discharge summary says a social worker visited me and I spoke gibberish to her. I don't remember it. I barely remember anything after the second day.
I spent 11 days in the ICU before being transferred to the psych ward. They continued giving me thiamine infusions 3 times a day for several weeks (plus naltrexone and other stuff) until the cannulas started tissuing and a bunch of my veins collapsed because they were being stabbed so much. On two occasions the infusion was accidentally delivered directly into the muscle, which was a 9 out of 10 for pain.
5 years later, my kidneys are still damaged, but not catastrophically. My liver function was impaired for a couple of years but it's within the acceptable range now.
Verdict? It was a terrible experience. I didn't die, and my discomfort was intense and prolonged.
I'm just glad I avoided brain damage, which is supposedly common in this situation.
Don't try it.