I getting cautious in my old age... I don't know if these things are ever "safe". You never know if someone has an undiagnosed (or undisclosed) heart condition or epilepsy or something like that...
One thing I can tell for sure is that this thing would have to be battery powered for safety reasons.
Police tasers operate off of small batteries and once in awhile someone dies. Of course, your little circuit isn't supposed to as strong as a taser, but...
The regulations in most countries require anything over 50V to be insulated or enclosed so nobody can touch it. And, you usually can't feel 50V, although you can "feel" a 9V battery if you touch it to your tongue.
Here is something I found about electrical safety.
Those things are usually more than 1000V with limited current (so the voltage drops with a low resistance load). If you understand how an inductor works, it's not that hard to limit the current by limiting the amount of current that you "charge" the inductor with.