I have similar (very little) recession at the corners of my hairline. It's been a slow moving backwards over these past few years (I'm 27 now). I wanted to nip it in the bud so I started on Rogaine Foam (5%) and finasteride about 7 months ago. I also tried 1% Nizoral, but found that it irritated my scalp far too much due to my generally sensitive skin.
My dermatologist prescribed me the finasteride and briefly mentioned that only a very slight percentage of men experienced some sexual side effects while on it. I didn't really give it much thought at the time because she made it sound so uncommon, plus I'm a young healthy person and hadn't ever dealt with any side effects while on any other type of medication.
Well, I can now say that I definitely experienced those side effects. At first, there was the slight testicular discomfort. Next, after about 2 months on the drug, I started noticing that my morning erections were gone. Also, my ejaculate had become more watery and overall there was just less of it. I've never had ANY sort of problem with being aroused before, so this started to concern me.
Over the next few months, I made sure to keep a close eye on these symptoms. I can honestly say I don't think there was any paranoia involved. I simply wanted to make sure this medication wasn't negatively affecting my ability to perform sexually. After the 5-month mark, I did notice that while I was able to still become aroused, I didn't have much of a sex drive the way I had in the past. I went through the breakup of a long-term relationship a few months before I started finasteride and didn't have a sexual partner over these months, but I noticed that my urge/desire to masturbate had also become nearly non-existent. Also, my erections weren't as firm and stable as they always had been.
It was at that point that I decided that it wasn't worth the risk and came off the drug. Thankfully, I have a ton of hair at the top and crown of my head now anyway. There is only some slight recession at the temples at this point. It's actually hardly noticeable anyway due to how I style my hair.
I've stuck with Rogaine and started applying topical spironolactone from this site as well over the past few months. I know it's a long shot for it to have much of an effect, but I'm glad that I'm at least fighting DHT in some form, even if it's not the most ideal way (finasteride). I don't think my recession in these areas has continued, but I also haven't really seen any regrowth either.
I'm not sharing this story to scare anyone out of trying finasteride, but I thought I'd share my experiences because everyone should know that the side effects of this drug can be very real and you shouldn't take the decision of starting to take finasteride lightly. I've read other research and am starting to think that the side effects are much more common than the "1-2%" figure that propecia throws out there.