Been on 5mg., once per day for over ten years. No neg. side effects. I believe the half life is 24 hours. Were I to cut them up and divide the doses my body would maintain a higher blood level, but I have not seen any studies that show that method would allow better results for my hair. Plus, I just don't feel like chopping those "non-easily-dividable" things up. They splinter and rarely if ever break into equal parts. I'd have to see some pretty convincing evidence on the efficacy of doing it that way to bother with it.