Yes, that's why they make a 2.5 and 5 mg for just this reason; it's a very low dose.  The maker states men can actually take 10 mg daily and still be safe. The 20 mg can last an entire weekend with a decent half life. 
Remember, it's just an enzyme inhibitor and can be very good for cardiovascular health among other things like higher blood flow to your brain and organs.  I take 5 mg each night before bed (for a lot of good health reasons) and it works like a charm AND a big plus is the pump I get at the gym with crazy vascularity!!!  
Love the stuff
 
You can get the generic online and it's not expensive...think along the lines of costs for you supplements.