I have previously taken a nortriptyline OD, so not amitriptyline, but very very similar. I think I took around 800 mg (not sure how toxicity differs between the 2), alongside minor amounts of citalopram, prochlorperazine and promethazine (aka different to the protocol). I took the overdose to self harm, not to ctb, so I can't advise on that aspect of it.
From what I remember, the taste was absolutely horrid (I had been taking it as migraine medication, and beforehand I was on amitriptyline, which iirc has a similar taste), to the point where I didn't finish taking the rest of the other medications I had as I felt so nauseous.
I was taken to the hospital probably just over an hour after I finished taking the tablets, so again, can't really say much about what the dying process is like, but I guess I can comment on the effects of an OD. Basically, I got taken to A&E, I remember not wanting to speak to the receptionist and asking my dad to do it whilst I went toilet. This was my last clear memory. I then vaguely remember waiting to be triaged as well as being called by the triage nurse, but after that I have no recollection of anything that happened until around 36 hours after.
From what I've been told, the second the triage nurse saw I had taken a tricylic antidepressant OD, I got sent straight through to treatment. During this time, I had moderately reduced consciousness, but with a normal brain CT scan. I did have a couple of grand mal seizures, which caused issues with my lungs. I did not have any issues with my kidneys. Other than some issues with malnutrition and inflammation caused by the OD, my bloods were fine.
My memories are patchy from just after the 36 hour point that I can't remember at all. I remember initially being completely unable to move because of how badly I was shaking (i.e. unable to control my whole body), including the fact I vaguely remember triggering a seizure because the nurse made me try get up to go toilet. If I wasn't trying to move, the shakes weren't an issue though. I was very much still out of it - I was still in A&E at the time, where you get moved around the different sections a lot and it felt like I would blink and find myself in a different area (as I was very confused and struggling to stay awake).
I was in A&E for 1 night (the bit I was unaware of), before being moved onto a ward shortly after I regained consciousness. The shakes quickly got better to the point where I was able to be transferred into a wheelchair some hours after and then stand with support for an x-ray. Probably at the 48 hour mark, I could walk again, but I was still very unsteady from the shaking and could only walk very short distances (i.e. from my bed to the bathroom directly opposite.)
I was on the ward for 2 more nights, as I had quite bad tachycardia (to be fair, this didn't have much effect on me as I wouldn't have realised my heart rate was off if I wasn't hooked up to a monitor). I remember it being very noisy (most of the other patients in my bay had dementia/delirium). The psych liason came to see me and cleared me to go home (luckily for me I have an EUPD diagnosis on my records, which in this case made my mh team view me as attention-seeking, so they refused to act on me harming myself).
I think the main effect on my health was the fact that the lung issues caused what the doctors treated as aspiration pneumonia. Again I didn't really notice this physically, but I did have to take stupidly high doses of several antibiotics for a bit after being discharged, which was horrid.
Being completely honest, if I hadn't thrown away my nortriptyline stockpile in a moment of wanting to recover from self-harm, I would probably do it again. For me, other than the complete loss of dignity from being completely reliant on others for a little bit, it allowed me to get the peace from my brain that I so desperately needed and I wasn't left with any physical harm after a week or so of recovery. However, there is always the risk of permanent damage when doing something like this (i.e. I could've gotten off lucky by not suffering long-term harm, you might not, especially as you wouldn't get prompt medical help like I did if you're trying to ctb). Also, the experience was deeply traumatic for those around me (especially in the 36 hours I was at my most unwell) and still affects them to this day over a year later - I'm unsure what your relationship with others are, but if they found you/saw you unwell from the OD, it would probably have a significant impact on your relationship. I personally had to stop taking promethazine afterwards because it reminded me too much of the OD (as it was the last tablet I took) and the smell of nortriptyline would give me flashbacks to taking the tablets.
Personally, I wouldn't recommend this as a method to ctb. The amount of time it takes to die is rather long, and if you were conscious, from the amount I suffered initially with prompt medical intervention, I can guarantee it really isn't going to be pleasant if you're waiting for it to kill you and will instead be very difficult to wait out. I would recommend taking time to research other options and see if there's anything that might be better.
I fear I may have gone on a bit too much and most of this is irrelevant given that I wasn't attempting suicide, but hopefully this gives some insight into what surviving a tricyclic antidepressant OD might look like :)
