Medically reviewed by Kristin Hall, FNP
Written by Our Editorial Team
Last updated 8/23/2020
Finasteride, the active ingredient in Propecia®, is an oral medication that’s designed to treat and prevent male pattern baldness.
Along with minoxidil, it’s one of two science-backed medications proven to help you keep and maintain your hair. In some cases, using finasteride may help you regrow hair in areas of your scalp that have been affected by hair loss.
If you’ve searched online for information about finasteride, you might have noticed that it’s sold in two different strengths: finasteride 1mg and finasteride 5mg.
Although these two medications contain the same active ingredient, they’re designed for slightly different purposes. We’ve explained the main differences between the 1mg and 5mg finasteride tablets below, along with information on which option is best for you.
Finasteride belongs to a class of medications called 5α-reductase inhibitors. It works to prevent hair loss by inhibiting the actions of 5α-reductase, an enzyme that’s responsible for converting a percentage of the testosterone your body produces into dihydrotestosterone, or DHT.
DHT is the key hormone responsible for male pattern baldness. If you’re genetically sensitive to DHT, the DHT produced through the 5α-reductase enzyme can target your hair follicles, causing them to miniaturize and stop producing new hairs.
Over time, this can result in everything from a receding hairline to complete baldness along your hairline and scalp.
We’ve covered this process in more detail in our guide to DHT and male hair loss. You can think of finasteride as a metaphorical shield that blocks DHT at the source, allowing you to block hair loss and maintain your hairline.
Although DHT is most commonly associated with hair loss, miniaturizing your hair follicles isn’t the only effect it has on your body. DHT also stimulates the growth of the prostate, leading to a condition called benign prostatic hyperplasia, or BPH, in many men.
BPH is relatively common, particularly in middle-aged and older men.
According to the National Institutes of Health, BPH affects about 50 percent of men aged 51 to 60, and as much as 90 percent of men aged 80 and older.
Since growth of the prostate is stimulated by DHT, finasteride is commonly used as a treatment for BPH. In fact, treating BPH was the original purpose of finasteride — it wasn’t until five years after it first came onto the market that it was approved by the FDA to treat hair loss.
Finasteride is most commonly used for hair loss at a daily dosage of 1mg. The vast majority of hair loss medications containing finasteride use this dose, including the original 1mg Propecia tablets.
Used daily, a 1mg dose of finasteride is highly effective at stopping hair loss from male pattern baldness. In a 2004 study published in Dermatology, finasteride 1mg used daily resulted in an increased intensity of hair in 80 percent of men with mild to moderate androgenetic hair loss.
There’s no need to take more than 1mg of finasteride every day — using a higher dose of the medication won’t improve your results, although it may increase your risk of experiencing side effects.
If you have benign prostatic hyperplasia (BPH) and you’re prescribed finasteride for treatment, you’ll likely receive the 5mg dose of the medication.
This dosage of finasteride is often sold under the brand name Proscar®. It’s intended specifically to control growth of the prostate and is not suitable for use as a treatment for hair loss.
Finasteride 1mg and finasteride 5mg both contain the same active ingredient, although they’re intended for different purposes. The first is designed to treat hair loss caused by DHT, while the second is designed to treat benign prostatic hyperplasia (BPH).
If you’re prescribed finasteride, make sure you only take the medication at the dose prescribed to you by your healthcare provider. Using a higher or lower dose of finasteride than recommended can affect your results and increase your risk of experiencing side effects.
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