I've always has a thick, healthy head of hair (still do)... I ran a number of cycles including de-ca, proviron, test... never had a single hair fall out... then when I ran a test, d-bol, proviron, and N P P cycle, I had the worst side effects, including hair loss... it came pretty suddently, absolutely no warnings...I'd notice 5-10 strands of hair fall out every time I showered, every day... that was a big deal for me because I've never lost a strand of hair in my life... of course I freaked... I immediately ordered some MinSaw-A topical lotion (minoxidil, Saw Palmetto, Retinolic Acid) as well as spirinolactone... I used them for several months.... to be honest, I don't know that I noticed a huge difference, but to be fair, you're supposed to run this stuff for long periods of time... I wound up buzzing my hair... didn't lose any hair after that.... it's been almost a year now since.... my hair is fully grown back, no more shedding...
Long story short, your hair will likely all come back... unless you're genetically predisposed to lose it anyway, then A A S will just speed that process along. If you already have hairloss issues, stay away from strong androgens (tr-en, proviron, etc)... and you may want to start running hairloss products before you start cycling, during and well after.