It is best to be on the safe side
Possible interpretation: 1) Don't take risks. Be careful and cautious. 2) It's best to be sure. It's best to be absolutely certain.
- My doctor says he doesn't think I've broken any bones but it's best to be on the safe side and have an x-ray.
- I feel pretty healthy but just to be on the safe side I asked my doctor for a check-up.
"It is best to be on the safe side" just to