Hi. Can tamoxifen have this side effects if uset by male for gyno, water retention, acne and weight gain?

why use Tamoxifen. Tamoxifen has no serious side effects like you have described. It is very well tolerated drug in general. But who do you have to use it in the first instance? It is only useful for treating breast cancer both in females and in males who suffer from cancer.
Hey man... Outpatient surgery for gynecomastia is a much better option than medication that is going to make you sick. You describe yourself as having gained weight as well -- you might instead / also have psedogynecomastia, which tamoxifen won't touch and which a surgeon / liposuction person can treat easily. This may be the boost you need to get your life turned around. Best wishes.