After taking combination therapy (5 mg amlodipine +10 mg lisinopril)my blood pressure fall to 85/55 is this ok or dangrous?

Not perfect: That level of drop in bp, from what i assume was a number that was abnormally high, is greater than it should be, and suggests that you are on more therapy than you need. Sometimes, with the first dose of a vasodilator, the drop is higher than it will be on subsequent doses, but it still suggests you are on more medicine than you need. Dehydration can also cause this type of response.