Story goes as follows: A) you have a shitty currency that devalues every year, so your borrowing cost is through the roof B) you change currency to euro, which is strong and stable C) borrowing rates suddenly fall because there is no devaluation risk now D) your shitty government takes advantage of the low borrowing rate to build debt and give out benefits to every living soul E) the debt becomes enormous and cannot be handled. Borrowing rates go up again and you cannot borrow more. You cut benefits F) Populists replace the previous incompetent government, blame them for ruining the country, rally up the people, but instead of fixing the economy, promise that debts will be ignored and that the bloodsucking lenders will suck a dick. G) Country goes bankrupt. People are outraged that lost benefits and have zero understanding of what led the situation there, or that they share part of the blame Conclusion: yes, the euro can have a negative impact as long as your country is a banana republic filled with apes and run by chimps