Can you get prescription medications without a blood test? say zoloft, (sertraline) for instance. do i need a blood test to be prescribed that?

Probably not: Sertraline in conventional use does not necessitate blood work although a possible side effect is a phenomenon called hyponatremia that just means low sodium. If the amount of sodium in the serum of an individual that is taking sertraline were to decrease too much then harm may result that may not be completely reversible. Hyponatremia is diagnosed after blood work called a serum sodium level..

Blood tests: It is advisable to do baseline blood work prior to starting any medication, to make sure no abnormalities exist that could interfere with future treatment.