Several years ago drug testing was introduced to major international kendo competitions. To the best of my knowledge there have been no positive tests. I am not even aware if anyone has actually been tested.
It is however interesting to reflect what benefit drugs could bring to kendo performance. I have asked more knowledgeable individuals about this and the only consistent answer I get is that as with many sports, steroids can be used to train through injury, thus reducing down-time.
To the best of my limited understanding, drugs and blood-doping are used in many sports to affect various elements of performance. Amphetamines are used to speed reaction times, in the case of precision sports like shooting, beta-blockers are used to slow them down. Steroids, testosterone and growth enhancers are used to increase muscle mass; blood doping is used to extend endurance and stamina. I cannot personally understand how any of these can on its own improve kendo performance.
Kendo relies on the ability to react quickly at the right time, so it calls for a combination of calmness, concentration and the ability to use fast-twitch muscle action only when it is required. Give or take the occasional long encho, it is not an endurance sport; so outside the realm of normal fitness training, stamina enhancement is not a pre-requisite.
Excessive upper body strength would appear to hinder rather than benefit kendo. Although it could be used in tsubazeriai and taiatari, it is more likely to lead to hansoku than ippon and it is obviously detrimental to achieving a smooth, fast cutting action.
Now it is probably obvious by now that this is a subject that I know very little about; but in my view because kendo is not only a competitive sport, but a way to discipline the mind and body, drugs are totally out of place.
Quite a few kendoka are however partial to the odd beer. From a kendo perspective, my only advice is to do this after keiko not before. For more specific advice on how alcohol relates to your health , you will get more reliable information from your doctor.
On a more serious note I would welcome your thoughts on whether or not drugs can be used in kendo and the effects they may have.