Nectar is the drink of gods. It is also used for healing by demigods. If a mortal eats it, they would be incinerated. A demigod can eat a little, but taking an overdose could make them feverish. A huge overdose would cause them to incinerate as a mortal would.
When mixed with any kind of alcohole any person will instantly black out after one drink. This will wipe they're memory.