You're better off telling them you are really nervous, and asking them to prescribe you one Valium beforehand. Alcohol won't do what you want it to do, and if you appear for the biopsy smelling like you've been drinking, that is not what you want the doctor to write in your file. (The sweat glands in your crotch region will give you away if your breath doesn't.) And yes, some medications do conflict with alcohol.