I have found though the rules are most mentally ill can donate blood some areas have limited certain psychotropic drugs and problems because the process is one where the blood is filtered through a machine and then a portion of that is returned back to the body.

with some medications the machines end up removing the meds. from the persons body and then it doesnt get returned.

think of it like if you pour salt into water, then you filter that water because of iron or lead content. some or all of that salt is removed along with the iron and lead. the water that is returned doesnt have as high dosage of salt left in the water.

some meds end up getting removed in the process that is used when giving blood which means a mentally ill person who needed that medication may end up going into active symptoms and problems mode because their medication isnt there in their body any more or at a smaller amount.

to find out if your meds prevent you from giving blood based on your locations donation facility rules contact your donation center.