Developing a Tolerance to Minoxidil and Propecia?

Hello Dr. Rassman,
I understand that your overall opinion on askdocweb isn’t too good.. however, I read something on their website that I thought I should consult you about.

The “doctor” mentioned that it is possible for users to develop a tolerance towards minoxidil and propecia. Is it true? Also, this “doctor” mentioned that the FDA reports stated that hair regrown by minoxidil does not last more than 48 weeks. Is that true as well? Here’s the link: AskDocWeb

Thank you, Doctor! Best Regards

Minoxidil, originally and still used for the treatment of hypertension, was incidentally found to increase hair growth and is now used in products such as Rogaine. When used as an antihypertensive, it has been shown in one study published in the Journal of Cardiovascular Pharmacology (J Cardiovasc Pharmacol. 1980;2 Suppl 2:S93-106), that there was no development of tolerance if it was administered long term. I would suspected that the same may be the case for topical minoxidil, but have not seen any evidence to support this.

The same can be the case for Propecia. Propecia (finasteride) has been used by urologists for the treatment of benign prostatic hyperplasia (BPH), and is currently the only FDA approved medication to treat hair loss by decreasing the levels of DHT, one of the key cause of male pattern baldness. In a recent study published in the Journal of Urology in July of this year, the authors noted that “long-term (more than 4 years) treatment with finasteride … led to a consistent, clinically significant reduction in total prostate volume compared to placebo in patients“. Again, extrapolating this information to the hair transplant/treatment arena, we can suspect that the same may be true for hair regrowth.

As for whether minoxidil hairs don’t last more than 48 weeks — read this study from Journal of the American Academy of Dermatology. The trial was 48 weeks long, and I’m guessing this other site you referenced either got confused or they’re making stuff up.