It´s illegal, but also it´s not something the police list as something they really care about, if the find it they will take it and give you a fine. The customs are getting quite strict, so be careful to order from outside EU.
You have to be taken with huge amounts before facing jail time, most get a house arrest and still it´s because of bigger amounts. If you keep under 2500 units as they call it, it will be looked at as personal use. 1 unit can be 1 pill, 1 vial and so on. So injects are better to get caught with than pills