Second experience with Tramadol / Paracetamol (Ixprim) : BAD.
This time I tried it after a nocturnal ejaculation (well, it was 8 am). After maybe 20 minutes I became more and more nervous. Around 10 am, as this nervosity was becoming greater and unpleasant, I was somewhat suspecting that Tramadol was not working as well as with the last orgasm, which was voluntary, maybe because the neurotransmitter cocktail was different in both cases (something with noradrenaline or serotonin, as Tramadol has SNRI properties). I decided to try being aroused and found something for this on the internet. I don't know if it was because of that or if it was simply the logical continuation of what I was enduring since 8.30 am, but after not more than 1 minute of mild arousal, things became very very bad. I started a big anxiety crisis, had important shivers, tachycardia, difficulties speaking and also a beginning of tetany but I managed to stop it. As it was quite frightening, I called the emergency medical service, the doctor (who also seemed to know POIS, apparently) told me it was a typical serotonin syndrome due to Tramadol. Now it's almost 2 pm in my country and most symptoms have vanished, though I'm still a bit nervous.
I suspect that I had several mild serotonin syndromes in the past, more or less linked to POIS. In particular, in september I tried to take 100 mg of L-theanine before sexual arousal (it's in Quantum's and nanna1's prepacks in higher quantities), and it gave me quite the same symptoms (though before that, it calmed me down and allowed me to masturbate a little without the immediate symptoms I usually encounter - maybe because L-theanine has both GABAergic and serotoninergic effects, or because it's a mast cells stabilizer).
I've read that some other people have experienced serotonin syndromes linked to POIS (notably berlin1884, if I remember well ?).
As for Tramadol, I'll definitively not re-use it, but this episode leads me to think that the benefits of my first trial were due not to the SNRI effect but to other properties of the opioids in it (well, it's not 100% sure, I guess). Also, I still don't have the usual post-orgasmic fatigue and this kind of thing. EDIT : I had absolutely no symptom remaining 24h later.