Is low blood pressure dangerous?

Depends: Low blood pressure is only dangerous if it is impairing adequate oxygen delivery to meet the needs of vital organs of the body, or if it signifies an underlying process that is dangerous if it worsens (e.g. Diffuse bacterial infection, or toxin poisoning). The actual number, in and of itself, is not dangerous if all organs remain working fine.

Yes: But only if it's really low. Another way to look at it is this: no one dies while their BP is high. All people who die have low BP at the end. That said, if you're otherwise healthy and your BP is on the low side, it's a sign of health, not disease!