Is it ok to have low blood pressure? how low can it go until its serious

Low BP is OK...: If you are otherwise healthy, and not acutely ill (in the hospital or icu), "low bp" is of no consequence. When you are critically ill, low BP can be a sign of shock, which is fatal if untreated.

OK: Usually low blood pressure is ok as long as you are not experiencing dizziness or passing out. Make sure to stay hydrated and see your doc if you feel any dizziness with your low blood pressure.

Depends : If you low blood pressure from having diarrhea and have dizziness it is a sign of dehydration. Which could be dangerous. You need immediate rehydration and electrolyte replacement.