Propecia (finasteride) is a drug used to treat male pattern baldness (i.e. androgenic alopecia) and is fairly effective at both reducing hair loss over time and increasing hair count (at least initially).
On average, after starting Propecia, it takes around 3 months of daily use to begin seeing benefits and it must be continued for these benefits to remain.
Your question deals with what happens if you stop Propecia and the answer is, unfortunately, that it stops working.
You likely won't notice anything occurring only 11 days after stopping the drug but over time, your hair will return to what it looked like before you started therapy (and likely even worse since a period of time has passed since the time you started the drug and male pattern baldness continues to progress as time goes on.)
The prescribing information for Propecia discusses this specifically:
In general, daily use for three months or more is necessary before benefit is observed. Continued use is recommended to sustain benefit, which should be re-evaluated periodically. Withdrawal of treatment leads to reversal of effect within 12 months.
So, there you have it. When you stop Propecia, you will likely see a reversal of any hair growth seen from the drug within 12 months and clinical trials for Propecia have shown this.
In one such study, men who were treated with 1 mg daily of Propecia saw a significant increase in hair growth after being assessed 12 months later (a difference of 107 hairs per one-inch diameter circle when compared to placebo).
However, when this same group of men stopped Propecia, after 12 months (from discontinuation) hair counts were below what they were when they first started therapy. This essentially means that the effects of the drug had completely worn off in the 12 months since stopping and the condition (male pattern baldness) had continued to progress, which is what we would assume.
Based on how Propecia works, which I discuss briefly in the section below, you wouldn't expect to see a dramatic change all at once when you stop it (or in 11 days as per your question). Rather, you are simply going to see a slow progression of hair loss back to your original starting point and the condition will continue to gradually worsen.
How Propecia Works
Propecia doesn't directly stimulate hair growth, and its effects take time to see (whether you are looking at the effects of starting it or stopping it).
The drug is classified as a 5-alpha reductase inhibitor. 5-alpha reductase is an enzyme that converts testosterone to dihydrotestosterone (also known as DHT).
Increased levels of DHT in the scalp and hair follicles are strongly associated with hair loss. Therefore, one way to reduce hair loss is to decrease levels of DHT, which is exactly what Propecia does.
Since Propecia inhibits 5-alpha reductase, less testosterone is converted to DHT and thus, there are lower DHT levels in the blood and scalp. This results in a reduction of hair loss (i.e. shedding).
Advantages And Disadvantages
As is the case with all drugs, you need to weigh the potential benefits of therapy with the negatives (e.g. side effects etc...).
This is a discussion best had with your doctor, but I can certainly discuss a few points here.
The obvious advantage of using Propecia is that it will, at least initially, likely result in hair growth. Additionally, it will slow the progression of hair loss over time.
In one clinical study for Propecia, men who used Propecia for over 5 years had more hair than what they initially started with (i.e. at baseline), which is pretty great seeing how male pattern baldness just gets worse over time.
The negatives of the drug include:
- You need to take it every day and consistently over time for sustained benefit
- Concerns over side effects
When it comes to side effects, most concerning for men are the sexual ones. Potential side effects include:
- Decreased Libido: 1.8% incidence rate
- Erectile Dysfunction: 1.3% incidence rate
- Ejaculation Disorder (Decreased Volume of Ejaculate): 1.2% incidence rate
As you can see, these side effects aren't overly common, but certainly something to be aware of.
Overall, Propecia is effective and relatively well tolerated, although some people may experience sexual side effects.
Whether or not you want to continue on the drug is up to you (and your doctor of course).If you do stop the drug, as discussed in this answer, you'll see a reversal of the effects it has had within 12 months.
Propecia is a drug used to treat male pattern baldness. It must be taken every day to see benefits (which are typically seen after 3 months of consistent use). After stopping Propecia, you can expect a reversal of its effects within 12 months, but it will be gradual. Studies show that 12 months after stopping Propecia, hair volume will likely be less than what it was before you started the drug in the first place simply due to the progression of the condition (male pattern baldness), which gets worse over time.