Are lampreys dangerous

No, lampreys are not dangerous. Though you may see people coming out of lakes or freshwater ponds with them attached to their body, it does not harm you. Sometimes lampreys attach to objects to fight the current, it is not sucking out your blood. I imagine that humans don't taste very good to lampreys as they suck the blood of FISH. Not humans. Though I do have to say they look pretty scary... hope this helped!