Is spironolactone a safe treatment for hirsutism? does it cause weight gain and harmful side effects?

Yes: This drug has some activity in blocking the male hormone receptors and is moderately effective for hirsutism. At the usual doses it has no major side effects and does not cause weight gain. If it does not help you, you could ask your doctor to try a drug called flutamide which is somewhat more potent but with a risk of liver side effects.