The value of a virtual currency I have acquired has dropped below the purchase price and I exchanged them for euros at a loss. May I deduct the losses in taxation?

Yes. If the result of your use of a virtual currency is a loss, the Tax Administration will primarily deduct it from your capital gains, if any. If such gains do not exist, the deduction will be made from all of your capital income. If you have no capital income or if said income is lower than the losses to be deducted, the deduction will be carried forward to the following 5 years.