It is recommended that you do NOT drink alcohol whilst taking Spedra.
However, it is not dangerous to drink alcohol at the same time as taking Spedra. Drinking alcohol and taking Spedra amy increase your heart rate and lower your blood pressure. You might also feel quite dizzy (especially when standing up), have a headache, or feel your hear beating particulary quickly. or strongly in your chest (palpitations).
Drinking alcohol amy also reduce your ability to achieve an erection, meaning drinking alcohol may have a counter-productive effect when taking Spedra.