you can have a sudden drop in blood pressure depending on how close the dosage timings are from each other.
if 50mg has been working for you, then i would just stick with that. i've tried different dosages of viagra when i used to play around with it. I found that 50mg got the job done perfectly for me, however when i upped the dosage (did 75mg and 100mg ((thinking more is better)) ), the only difference i saw was the side effects were intensified. So, in other words, if 50mg gets the job done? then stick with that, otherwise your just asking for worse headaches and nasal congestion symptoms.