Finasteride and sexual side effects: what to know before you start

How finasteride works, and why it can affect sex

Finasteride blocks 5-alpha-reductase, the enzyme that converts testosterone into dihydrotestosterone (DHT). DHT drives the gradual shrinking of hair follicles in pattern hair loss, so lowering it can slow or partly reverse thinning.

DHT also plays roles in the prostate, genital tissue and possibly the brain. That is the likely reason some men notice sexual or mood changes, though the exact mechanisms of persistent symptoms are not well understood.

The side effects listed

MedlinePlus lists these possible effects of finasteride:

• Difficulty getting or keeping an erection
• Decreased sexual desire
• Ejaculation problems, including a lower volume of semen
• Testicle pain
• New or worsening depression, or thoughts of self-harm, which require immediate contact with a doctor

How common are they?

In clinical trials, a minority of men reported sexual side effects, and the rates were only modestly higher than in men taking a placebo. That means many men who notice changes on finasteride would have noticed them anyway, but some changes are clearly drug-related.

Expectation also matters. Studies of many medications show that people warned about a side effect report it more often. That is not a reason to dismiss symptoms; it is a reason to track them honestly and talk them through with your clinician.

When symptoms persist

MedlinePlus notes that sexual side effects may occur during treatment and after it ends. A small number of men report symptoms that continue for months or longer after stopping, sometimes called post-finasteride syndrome. How often this happens, and why, is not established, and research is ongoing.

FDA's April 2025 alert on compounded topical finasteride described 32 adverse event reports from 2019 to 2024, including erectile dysfunction, decreased libido, anxiety, depression, suicidal thoughts, brain fog, fatigue and insomnia. Most reports said symptoms continued after the product was stopped. Adverse event reports cannot show how common these effects are, but they are a signal worth taking seriously.

Who should be especially cautious

• Men with a history of depression, anxiety or suicidal thoughts
• Men already experiencing erectile or libido problems, so the baseline is clear
• Men actively trying to conceive, who should discuss timing with their clinician
• Women who are or could become pregnant, who must not use finasteride or handle crushed tablets because it can harm a male fetus
• Anyone whose partner or household members could be exposed to a topical product

Reducing risk and staying in control

• Note your baseline sexual function and mood before starting
• Start with the lowest effective approach your clinician recommends
• Check in at regular intervals, and report changes early
• Stop and contact your clinician right away for depression or thoughts of self-harm
• Remember that finasteride lowers PSA readings; tell anyone checking your prostate that you take it

Untangling other causes

Sexual changes in midlife often have more than one cause. Low testosterone, poor sleep, sleep apnea, heavy drinking, blood pressure and antidepressant medications, diabetes, relationship stress and simple aging can all affect libido and erections. If symptoms appear after starting finasteride, the timing is a useful clue, but it is still worth looking at the full picture.

Your clinician may suggest checking basic labs or addressing other contributors alongside, or instead of, stopping finasteride. If you have ongoing erectile problems, there are effective treatments, and erectile changes can sometimes be an early sign of heart or blood vessel disease worth discussing.

If you prefer to avoid finasteride

Minoxidil, applied to the scalp or taken by mouth at low dose under supervision, works through a different pathway and does not affect DHT. It is less effective for some men on its own, but it avoids hormonal side effects. Your clinician can discuss a formula without finasteride.

How HealifyMD approaches it

Your clinician reviews your mood history, sexual health and plans for children before prescribing, explains the trade-offs and schedules follow-up. You can stop at any time; hair gained on finasteride is usually lost within about a year of stopping. The 4-in-1 Hair Loss Treatment is $199 (one-time), confirmed after your eligibility review. It is a compounded formula: it is not FDA-approved, FDA has not reviewed it for safety, effectiveness or quality, and it is not equivalent to branded products such as Propecia or Rogaine.