Reasons for allowing and refusing generic substitution and factors determining the choice of an interchangeable prescription medicine: a survey among pharmacy customers in Finland.

GS is a common practice in Finnish community pharmacies. The price of the medicine was the most important factor affecting customers' decision to allow or refuse GS and the choice of an interchangeable prescription medicine. Thus, customers should receive information about medicine prices at the pharmacy in order to help them make their decision. However, individual needs should also be taken into account in counselling because customers regard several factors as important in their choice of an interchangeable medicine.