To guarantee the quality of our analyses, you must observe some rules before any sampling.
First, check if you have to be fasting for the sample (for 8 hours before the blood draw).
In general, smoking should be avoided.
It is not forbidden to take medication before a blood test, except when this blood test is used to dose the drug (Digoxin, Elthyrone, ...) or when your doctor does not advise you expressly..