Does spironolactone damage kidneys? Is it okay to take spironolactone for 6 months or for 1 year?

Thank you for your question. You’re asking if spironolactone damages your kidneys, and if it safe to take for 6 months to a year. Your question is appropriate for female pattern hair loss, and is a common question often discussed in our practice with patients with this condition.
A little of my background: I’m a Board-certified cosmetic surgeon and Fellowship-trained oculofacial plastic and reconstructive surgeon. I have been in practice in Manhattan and Long Island for over 20 years. I am the founder of TrichoStem™ Hair Regeneration Centers, based on a system we developed for men and women with androgenetic alopecia using Acellular matrix and platelet-rich plasma (PRP). We’ve doing this treatment since 2011, and developed a system that is working both with patients who are already on spironolactone, as well as with most of our female patients who have never been on spironolactone.
To understand the logic behind the use of spironolactone, when I see patients who have female pattern hair loss, typically a dermatologist prescribed spironolactone as a way to block testosterone. Their working diagnosis is androgenetic alopecia is due to testosterone sensitive hair follicles, so they suppress the testosterone. It is known that this drug is a diuretic, so it works in the kidneys. I think the way this question is most appropriately answered is to discuss the impact of spironolactone on the kidneys with your doctor. It is routine to have lab tests done to check kidney function. I can tell you that I have patients who have been on spironolactone for years. In fact, many birth control pills have spironolactone to help, for example, patients with acne. Acne is also associated with an imbalance in testosterone, and testosterone blockade has certainly helped patients with acne.
From a clinical perspective when we treat patients with Hair Regeneration, and to go back to the origins of this treatment, we developed it after using a material called extracellular matrix with platelet-rich plasma (PRP) to help patients with hair transplants have better healing. We wanted the donor area to heal better and we wanted the hair grafts to survive. As a positive side effect, this stem cell-based technology also resulted in thinning hairs becoming thicker.  
Hair Regeneration has been a significant benefit for our patients who come to us from around the world with female pattern hair loss. Until this point when we’ve taken on this challenge, there really was not much available for female pattern hair loss treatment. Besides the use of spironolactone, there was also minoxidil, but I can tell you that most of our female patients who have tried minoxidil didn't find much value in it.
For the effectiveness of spironolactone, anecdotally from the feedback I get from my patients, there’s a large percentage on the drug who aren't sure if it is helping. There’s a certain percentage of patients who say they did see an improvement being on spironolactone. Since I don't prescribe spironolactone, I leave it up to their dermatologist to decide whether or not to continue the drug, and I don't interfere with that process.
Hair Regeneration is an injection treatment that has consistently resulted in regrowth of hair, thickening of thinning hair, and prolongation of the hair growth cycle. With data now going beyond 7 years, it has had a very high success rate of about 99.9% or more for female pattern hair loss. It was a challenge for both male and female pattern hair loss to develop an algorithm, a system of dosing, and placement to get good results. With women we had many challenges in the early years, but ultimately it’s become really gratifying to help our patients treat a condition, which unfortunately there’s no other medical intervention in contrast to men who can take finasteride.
There is an opportunity for you to discuss your concern about kidneys with your doctor, and about the dosage. Since spironolactone is a diuretic, a lot of our patients mention they had to get up at night frequently to go to the bathroom, while others felt that they can tolerate the drug without any problem. This is also in context of your general medical profile, with routine lab tests to see kidney function, and also monitor that effect.
It’s important to explore other options for the treatment of female pattern hair loss. As I said, we’ve made a big impact with Hair Regeneration, and with a long history of experience, it is  very straightforward, with the exception of some diagnostic unknowns where patients appear to have female pattern hair loss, but also other conditions where we still have to do biopsies and look at other possible causes. However, for androgenetic alopecia, Hair Regeneration has worked out very well, and has been a sustainable approach without the use of other drugs. It doesn't mean there isn't value because I also explain to our female pattern hair loss patients that women’s scalps are particularly sensitive to hormones; and hormone balance where testosterone, estrogen, progesterone as well as thyroid and other important variables in the blood such as iron levels, and Vitamin D. Further, women appear to be sensitive to stress-induced hair shedding which is a distinction from genetic pattern hair loss.
It’s important to have a team approach when it comes to managing hair loss. That means being followed by a medical doctor, OB-GYN in terms of hormone levels and optimizing hormone therapy, if appropriate an endocrinologist, and a dermatologist. From our end, we can stimulate hair growth with Hair Regeneration, and we have a certain understanding of the predictability based on a patient’s profile. Spironolactone may have a value in your situation depending on your doctor’s opinion of the impact of testosterone on your hair loss. I hope that was helpful, I wish you the best of luck and thank you for your question.

Spironolactone acts on the kidneys but does not cause kidney damage in young healthy individuals. The concurrent use of drugs that affects kidney function or affect hydrational status can sometimes impair renal function. Please speak to your physician if you have specific concerns.