How long after having Serotonin Syndrome/Poisoning can I have another Avanza tablet? I had 90mg Avanza, as prescribed by my doctor, which was far too much, which I didn't know, on Sunday evening and spent 2 nights in hospital due to the poisoning. I have had hardly any sleep since Sunday, and want to know if I can take one of my 45mg tablets of Avanza to sleep tonight?