Medical facts:
1) Leeches are not harmful. They are good actually. They will only suck your dirty blood and leaves your clean blood alone.

2) If you donate blood, it doesn’t mean your red blood cell decrease. Your bones will regenerate new red blood cells and your body will be even more energized. But blood donations requires some stuffs like your body must weigh 45kg or more, sleep more than 6-8 hours and eat before donate…idk if this is correct.

Damn, I saw some people used the same cup to suck dirty blood that it bring diseases.