Why are doctors still prescribing Finasteride for hair loss? Is it worth the side effects?

 No question that Finasteride may cause some side effects in a very low percentage of patients. I prescribe the medication to my patients. It is the best oral medication for Male pattern Hair Loss and FDA approved. The other FDA approved medication with excellent results is topical Minoxidil 2 % and 5%. I will suggest you to schedule an appointment with a local hair loss specialist to review the possible hair loss treatments. 

Great question!
Not everyone experiences adverse side effects to Finasteride. Finasteride does demonstrate efficacy in regard to hair loss and has demonstrated efficacy in cases of enlarged prostate and recent clinical studies suggest it will help prevent most forms of prostate cancer. 
Thus, it appears to have its' place in conventional medicine until such time something better replaces it. Doctors attempt to strike a balance between benefit of treating the indication and side effects.       
Therefore, most doctors will prescribe and monitor patients for adverse side effects and when they occur the doctor will normally change you to something else.
Personally, Finasteride is certainly not my first go to medication for hair loss. This is demonstrated in the many times I have written on hair loss and Finasteride herein Realself. This is especially true for younger patients of childbearing years and women in general. 
Medications such as Finasteride and Minoxidil treat only the general symptoms of a problem. It is far better to accurately identify the root issues and specifically address them. Complementary Alternative Medicine and Precision Medicine as I practice, offer a wider array of solutions and produces greater efficacy with no to far fewer side effects.    
There are now many alternatives to Finasteride. For some, it may remain as easy as taking a pill a day, and for others its' a bit more complicated. Some alternatives are low cost and others are more expensive. Your individual condition is the determining factor.
There are treatments such as Bioidentical Hormone Replacement Therapy (BHRT) that not only safely provide good to great efficacy, but also improve one's overall health and wellness.
New peptides are now demonstrating good efficacy with no to far fewer side effects. Regenerative medicine techniques such as PRP (mild to moderate efficacy), PRP with cocktails of medications or biologics are demonstrating stronger efficacy than PRP alone with nearly zero side effects. 
Patient safety is always my first concern and then attempt to balance cost considerations with the budget of the patient. 
I hope I've helped answer your question.
Warmly,
Arbella Sarkis, MD