To put it in Lord of the Rings terms, "you’ve heard whispers of a nameless fear". But if sexual side effects are really an issue, why are millions of men still taking finasteride? Let’s make you an expert on the subject.
Not all clinical studies are objective, so we’ll be primarily quoting double-blind placebo-controlled trials in this article. These are trials where both the researcher and subject don’t know who is receiving a placebo—a technique used to totally eliminate bias.
Double-blind placebo-controlled studies show us that there is little to no relationship between finasteride and sexual dysfunction (Source). For example, in three FDA-controlled clinical trials lasting 12 months, more men in the placebo group reported adverse effects than those actually taking finasteride. (1.6% vs. 1.4%) (Source). Officially, the FDA reports that approximately 0.3% of men discontinue finasteride due to potential sexually adverse effects. The good news is all controlled trials show sexual side effects go away if you stop treatment.
It's easy to blame finasteride for sexual dysfunction in online opinion pieces, but hard to blame it in controlled clinical trials.
To understand the side effects, you need to understand how finasteride works. Finasteride decreases DHT, a form of testosterone which is not used for sexual function in adulthood. Finasteride then increases testosterone levels slightly which improves both sexual function and mood (Source).
In a double-blind placebo-controlled study using nocturnal penile tumescence (NPT) as an objective method of assessing erectile function, 5mg of finasteride failed to suppress consistent sleep-related penile erections. This means that when taking 5 times the dose used for male pattern hair loss (MPHL), researchers concluded finasteride did not affect erections (Source).
Finally, a 2016 meta-analysis of 17,494 subjects from 17 randomized control trials found finasteride does not cause ED when taken to treat MPHL and only sometimes causes a small decrease in semen volume (Source).
According to FDA labeling, some men may see a hormonal effect initially as their system gets used to the medication—in most of these cases, sexual side effects completely disappear after a few days or weeks. (approx. 1.7% of men reported sexual dysfunction, but only 0.3% stopped taking the drug).
There's also the placebo effect...
In every major clinical trial on finasteride, a significant number of men in the placebo group believed they got sexual side effects—even though they were taking a sugar pill. These men fully believed a drug altered their sex life, even though they weren't taking a drug. This is not a knock on those men, it's just how fear works.
Studies suggest most sexual dysfunction from finasteride comes from either a nocebo effect (where worries about sexual dysfunction are what cause it), or simply a separate cause of ED, which affects 18.4 percent of U.S. men age 20 and older regardless of whether they take finasteride. Many men start losing their hair during the same stage of life where they start losing their libido—with the reasons behind it being broad—everything from stress & anxiety to relationship issues and lower testosterone.
The mental-health reasons behind sexual dysfunction in men are why it's easy to blame finasteride in online opinion pieces, but hard to blame it in controlled clinical trials.
It’s been well documented that the overall incidence of sexual dysfunction is higher in men who are focused on sexual side effects compared to men who are not (Source). Fear-mongering, both in the media and online, are the key causes of this, and it’s been found that the frequency of consultations for sexual side effects from finasteride parallels the respective media coverage (Source).
In every clinical trial on finasteride, a significant (and sometimes larger) number of men in the placebo group report sexual side effects. These men fully believe they have gotten sexual side effects from a sugar pill. This is not a knock on those men, it's just how fear works.
For instance, a case study reported an otherwise healthy 40-year-old man had a 12-year history of ED. The man had not used finasteride, and described normal functioning in regular sexual activity in many relationships from his late teenage years to age 28, at which point his ability to sustain an erection markedly and rapidly diminished across a period of a few months. Despite taking a whopping 1300mg of sildenafil (Viagra), he could only sustain an erection for about five minutes. (Source) The researchers identified psychogenic factors, such as anxiety, as the primary cause of his condition.
In men who don't use finasteride, ED can potentially last for years (Source). The duration of ED can vary widely and the severity can range from mild to severe, with the prevalence increasing with age.
A 1999 randomized, double-blind, placebo-controlled study of 79 healthy men found that taking 1 mg of finasteride daily did not alter spermatogenesis, semen volume, or sperm morphology. Despite lowering DHT levels, testosterone and gonadotropin levels remained normal—indicating that testosterone, rather than DHT, is the main androgen regulating sperm production. (Source)
A 2007 study of 99 healthy men found that finasteride had no meaningful effect on fertility, even at 5 mg—five times the usual dose. Semen volume (mostly prostatic fluid from finasteride slightly shrinking your prostate) dipped slightly at 26 weeks, but sperm counts, quality, and hormone levels remained normal. A statistically significant reduction occurred only in the dutasteride group; however, even those short-term declines stayed within the normal fertile range and were fully reversible. All parameters returned to baseline in both groups within six months of stopping treatment. (Source)
Research shows that men no longer need DHT for sexual development or muscle mass after puberty. A 20 week study that almost totally suppressed DHT in men ages 18 - 50 (using a whopping 2.5mg of dutasteride) found that lowering DHT (in men with normal levels of testosterone) didn’t change their fat-free mass, strength, or sexual function. (Source)
On the other hand, testosterone—which Locklab increases slightly—is universally understood to improve sex drive and mood. (Source)
According to the largest study conduction on Dutasteride—a 0.1mg dose of dutasteride (the standard formulation in Locklab) did not cause ED at all, since the same number of men in the placebo group reported ED as men actually taking dutasteride (7/7 out of 917). Of course, as always, you may increase your chances for side effects by adding more of any drug, but we believe the benefits to your hair (for men with aggressive hair loss) outweigh the very low likelihood of side effects. (Source)
200% more men take finasteride now than in 2015, this is partly due to a better understanding of how low-risk, or even nonexistent most of the sexual side effects actually are. Even with a large fear campaign online, the overwhelming majority of men who take finasteride keep their hair without side effects of any kind. And since our enjoyment of sex is highly linked to how we feel about ourselves, improved hair often improves your sex life.
