Do Finasteride and Dutasteride Affect Libido or Erections?

Some men do notice lower libido, difficulty getting an erection, or changes in ejaculation after starting finasteride or dutasteride. These side effects are real, but they were uncommon in clinical trials and also occurred in men taking a placebo. There is no need to panic, but the possibility should not be dismissed either.

This article looks at finasteride 1 mg and dutasteride 0.5 mg, the oral doses commonly used for male pattern hair loss.

How common are sexual side effects?

One-year trials of finasteride 1 mg reported the following results.^{propecia-label}

Symptom	Finasteride	Placebo
Lower libido	1.8%	1.3%
Erectile dysfunction	1.3%	0.7%
Ejaculation disorder	1.2%	0.7%

At least one of these problems was reported by 3.8% of men taking finasteride and 2.1% taking placebo. That is a difference of about 1.7 percentage points. The difference is real, but most men taking finasteride did not report a sexual side effect.

In a small 24-week trial of dutasteride 0.5 mg, sexual side effects were reported by 16% of the dutasteride group and 8% of the placebo group. The study included only 117 men, and all reported symptoms resolved either during the study or after treatment ended.^{dutasteride-rct}

An analysis combining 15 trials and 4,495 men found that sexual side effects were 1.57 times as likely with finasteride or dutasteride as with placebo.^sexual-meta This does not mean that 57% of users had a problem. It means that a relatively low starting risk increased somewhat.

Do these drugs remove male hormones?

No. Finasteride and dutasteride do not block testosterone itself. They reduce the conversion of testosterone into another hormone called DHT. DHT plays an important role in the gradual shrinking of hair follicles in male pattern hair loss.

Libido and erections are not controlled by a single hormone. Stress, poor sleep, depression or anxiety, alcohol, smoking, diabetes, high blood pressure, relationship concerns, and other medicines can all have an effect. A change after starting hair-loss medication is not automatically caused by the drug, but it should not be ignored either.

Is finasteride or dutasteride safer?

Current research cannot clearly say that one is safer for sexual function. Studies directly comparing the two drugs found no clear difference in lower libido, erectile dysfunction, or ejaculation problems.^{head-to-head-meta}

That evidence included only three studies, 576 participants, and 24 weeks of follow-up. Dutasteride reduces DHT more broadly, but that does not automatically prove that it causes more sexual side effects. Switching from finasteride to dutasteride also cannot be assumed to solve a problem.

Can worrying about side effects make them feel more likely?

It may contribute. This is called a nocebo effect: expecting a side effect can make a person more alert to changes that might otherwise go unnoticed.

In one study of men with enlarged prostates taking finasteride 5 mg, those who received detailed information about sexual side effects reported more symptoms than those who did not.^nocebo The study used 5 mg, however, rather than the 1 mg dose used for hair loss.

A possible nocebo effect does not mean that symptoms are imaginary. The medication, anxiety, general health, and other factors may all play a part.

Do symptoms improve after stopping?

In clinical trials, most sexual side effects improved while treatment continued or after it was stopped.^{propecia-labeldutasteride-rct}

There have also been reports of lower libido, erectile dysfunction, or ejaculation problems continuing after finasteride was discontinued. Persistent symptoms are therefore included in product information and regulator warnings.^{mhra-2026propecia-smPC}

The available reports cannot tell us exactly how often this happens or prove that finasteride caused every case. It would be wrong to say that persistent symptoms never happen, but there is also not enough evidence to describe them as common.

What should you do if something changes?

Start by writing down what changed and when. Note when you started the medication and any changes in desire, morning erections, erections during sex, or ejaculation. This makes a medical conversation more useful.

Talk to the prescriber rather than reducing the dose or switching to alternate-day use on your own. Whether to continue, pause, or change treatment depends on how troublesome the symptom is and how much benefit the medication provides. Sleep, stress, mood, alcohol, medical conditions, and other medications may also need review.

Do not add an erectile-dysfunction medication without medical advice. This is particularly important for anyone with cardiovascular disease or taking nitrate medication.

The UK's medicines regulator advises patients to contact a healthcare professional if sexual problems develop while taking finasteride or dutasteride. Anyone taking finasteride 1 mg who develops depression or suicidal thoughts should stop the medicine and seek medical help promptly.^mhra-2026

Frequently asked questions

Can erections worsen even if libido is unchanged?

Yes. Desire, erection, and ejaculation are related but separate functions. Clinical trials recorded them separately.^{propecia-label}

Should I stop as soon as a side effect appears?

That depends on how severe it is, when it began, and whether another cause is likely. Discuss stopping or changing treatment with the prescriber rather than deciding alone.

Will stopping the drug make my hair suddenly worse?

The benefit maintained by finasteride can fade within about 12 months after stopping. This is generally a return to the underlying course of hair loss, not proof that the drug causes hair loss to rebound beyond where it would otherwise have progressed.^{propecia-label}

Bottom line

Finasteride and dutasteride can affect libido or erections in some men. In studies, however, only a minority reported these problems, and most symptoms improved during treatment or after stopping. Current evidence does not establish that one drug is safer than the other.

There is no need to exaggerate the risk or pretend that it does not exist. If you notice a change, the most practical next step is to discuss possible causes and the benefits and drawbacks of treatment with the prescriber.

Sudden shedding, patchy hair loss, scalp pain, inflammation, or scarring should not simply be blamed on medication. These changes warrant an evaluation by a dermatologist.