Tadalafil (Cialis)
Long-acting PDE5 inhibitor. 24-36 hour duration. Daily low-dose option for spontaneity.
PDE5 inhibitor with extended duration vs sildenafil. As-needed 10-20mg or daily 2.5-5mg. Daily low-dose is popular — allows spontaneous activity, also treats BPH. Side effects: back pain, muscle aches (slightly more than sildenafil).