It is not only European Central Bank stimulus that has the potential to hurt the euro.

From the possibility that Britain might leave the European Union and the impact of refugees flooding the region, to concerns over the economic outlook and political turmoil in Ireland as well as Spain, the euro is facing a slew of hazards. Set alongside economists' expectations for lower interest rates and more asset purchases from the ECB, investors are wondering how low it can go.

"There are monetary policy risks, there are political risks within the EU, there's the geopolitical risks from outside with migration, and underlying it all you've got a pretty lackluster growth picture," said Frances Hudson, an Edinburgh-based global thematic strategist at Standard Life Investments, which oversees $356 billion. "You could quite easily see a negative spiral developing."