It is not safe . I know a guy that took 3 pills and have been messed up for years. Check out a site called Propecia help and see the thousands of men there with horrific ongoing symptoms that have not went away even years after stopping this medication. I’ve read one guys post that says he would rather lose a limb than have post finasteride syndrome.
I have 25 years of experience prescribing finasteride so I know first hand what the risks have been. I have been managing finasteride with my patients and am always responsive when they develop side effects. I can’t explain why a man who took any drug that has a half life of 6 hours with just three pills, can have long term side effects, so I can’t help explain this to you.