I'm 19 and want to start taking Finasteride to combat receding hairline but I don't know if this would be the best option.

This needs an in-person evaluation. I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

In  my opinion, finasteride is the single best agent to prevent future hair loss and possibly obtain regrowth in a 19 year old with androgenic alopecia. It blocks conversion to DHT. We have also found the addition of PRP to be a helpful addition. Find a hair loss expert. Ask to see photos.

Finasteride has been known to cause various side effects after using the product, which are the result of hormone imbalances caused by standardized dosing of those medicines in oral form.
I would recommend a personalized medicine that is catered to your specific biochemistry that can solve the underlying cause of your hair loss.Any medicine that actually can make changes inside your body, are required under the FDA to be available by prescription only. This therefore means that it is not possible for anything that does not require a prescription to cure or prevent hair loss or regrow thinning hair. Thus, a personalized medicine will be the best choice because instead of a "one size fits all" approach, you will be taking something which is truly catered to your body's needs.
The treatment is out there. Good luck on your search.

Before staring the drug finasteride, I always perform a HAIRCHECK which shows in great accuracy the amount of hair lost at the time the drug is started. IF no hair is lost, I advise against the drug. If hair is lost, then I remeasure the patient one year later to see the value and the benefit, if any.For young men with a history of Gynecomastia, the drug finasteride is not any more risk in your situation than any other young man your age