medicine with potentially harmful side effects for cosmetic purposes

I have a halachic question. I am 22 years old and am begining to lose my hair. In order to slow down the process I am thinking of starting the drug Propecia (Finasteride).

However there appears to be some side effects from the treatment, among them (as extracted from a website on its side effects):

"Less common or rare

* Abdominal pain; back pain; decreased libido (decreased interest in sex); decreased volume of ejaculate (decreased amount of semen); diarrhea; dizziness; headache ; impotence (inability to have or keep an erection) "

[http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202649.html]

My questions are as follows:

1) Is one allowed to take a medicine with potentially harmful side effects for something that is purely cosmetic? Although there is an emotional and self confidence issues as well, it is clearly not an issue of life and death.

2) Some of the side effects in particular seem to effect the male reproductive organs. Are any of these side effects problematic from the perspective of Jewish Law? In particular I was concerned about this one "decreased volume of ejaculate". I am aware in Jewish law that there is a problem of "destroying seed". Would this potential side effect be included among that prohibition?