Doctors Warn About Rare Side Effects of Hair Loss Medication Finasteride

By: May Man Published: Jun 10, 2024

An increasing number of young men are taking a medication to prevent hair loss, raising concerns about rare but potentially long-lasting side effects. According to a report by Epic Research for NBC News, the number of men in the U.S. with finasteride prescriptions has surged nearly 200% over the past seven years.

“It’s like water in my clinic,” said Dr. Jerry Shapiro, a dermatologist at NYU Langone Health. “I’m prescribing it all the time.”

Younger Men Seeking Treatment to Prevent Hair Loss

Although the Epic report focused on men aged 25 and older, Shapiro and other doctors have noticed more young men, including some in their late teens, seeking treatment early to prevent hair loss.

man grooming hair looking into mirror

Source: Freepik

The rise in prescriptions is partly attributed to telemedicine companies like Hims, Keeps, and Ro, which heavily advertise the drug, noted Dr. Maria Colavincenzo, an associate professor of dermatology at Northwestern Feinberg School of Medicine.

Promoted by Social Media Influencers

Social media influencers also promote finasteride, sharing their hair loss and regrowth journeys. A popular Reddit community called tressless frequently discusses the drug.

A close-up of a person’s phone open to many social media apps.

Source: Julian Christ/Unsplash

“People are interested in treating it a little bit younger than what I saw before,” said Colavincenzo.

Potential Long-Term Impotence

Doctors affirm that the daily pill is safe but emphasize that it must be taken continuously to maintain its effects. Controversy surrounds the drug due to the potential for long-term impotence even after discontinuation.

Two doctors go over the information in a laboratory

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Finasteride, originally developed for treating an enlarged prostate and known by the brand name Propecia, has been FDA-approved for hair loss for nearly 30 years. It is a daily pill that slows androgenetic alopecia, or male-pattern baldness, which affects about half of men by age 50.

It May Lower Risk of Early Balding

Though no conclusive evidence guarantees that starting the drug early prevents baldness, doctors suggest it lowers the risk. Finasteride works by blocking the 5-alpha reductase enzyme, preventing testosterone from converting to dihydrotestosterone (DHT), which is believed to shrink scalp hair follicles and shorten the hair growth cycle, leading to hair loss.

A balding African-American man sits using a laptop computer.


“If you block that signal telling the hair to shrink, then the hair doesn’t shrink, and it might even unshrink a little bit,” Colavincenzo explained.

Determined by Genetics

Genetics largely determine why some men with high DHT levels don’t go bald, a subject of ongoing research.

3D representation of DNA

Source: Freepik

Most men taking finasteride successfully slow their hair loss.


Drug is More Effective at Prevention

Studies indicate the drug has an 80% to 90% success rate in preventing further hair loss, according to Shapiro. Starting early is key, as the drug works better at prevention and becomes a lifelong commitment.

Doctor holding out hand full of blue and white capsules

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“Most things in medicine are lifelong,” said Shapiro, who also advises Keeps, a company selling the drug online. “If you have high cholesterol you have to be on medication forever, or if you have high blood pressure you have to be on medication forever.”


Dermatologist Says Drug is “Very Effective”

Dr. Carolyn Goh, a dermatologist at UCLA Health, noted that while long-term data on finasteride’s efficacy is limited, existing data shows its benefits are maintained over time. A recent Korean study published in the Journal of Dermatology found that nearly 100% of men retained the same or more hair after five years on the drug.

A patient shakes the hand of his doctor during an appointment

Source: Freepik

“It’s very effective,” she said. “Although the response may be just keeping the hair from getting worse rather than necessarily growing hair, it works quite well.”


Less Successful at Regrowing Hair

Another study from Italy, which followed over 100 patients on finasteride for 10 years, found that 86% experienced no change in hair loss.

man looking into mirror suffering from hair loss

Source: Freepik

Despite its effectiveness in preventing hair loss, finasteride is less successful at regrowing lost hair. It is often combined with minoxidil, a topical drug that stimulates hair growth.


Hard to Gauge Effectiveness

Colavincenzo noted that patients using finasteride for about a decade have had success, though it’s difficult to gauge the drug’s effectiveness. “The hard thing is you often don’t know how well it’s working,” she said. “Even if your hair is just not getting worse it’s a success.”

An image of several doctors looking over reports during a meeting

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Since male-pattern baldness is considered a cosmetic issue, finasteride is typically not covered by insurance. Available as a generic since 2006, it usually costs less than $100 per month.


Possible Suicidal Behavior

In 2022, the FDA required prescription labels to warn of possible suicidal behavior in men taking finasteride, following advocacy by a patient group. A 2023 article in the International Journal of Impotence Research sparked online debate over post-finasteride syndrome, linked to decreased libido, erectile dysfunction, and cognitive difficulties.

A man sitting on a couch with his head in his hand.

Source: Nik Shuliahin 💛💙/Unsplash

Common side effects include reduced sex drive, difficulty maintaining erections, and decreased semen production, affecting fewer than 5% of men. There’s also a possible link to mental health issues, such as depression, though it’s unclear if the drug is the direct cause.


Proceed with Caution

“Certainly the vast majority of my patients have no such side effects and are fine and do pretty well with it,” said Colavincenzo. For men already experiencing sexual issues, Colavincenzo advises against finasteride.

Caution signs

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“I’m very cautious if a person tells me they’re having issues with sexual function,” she said. “I usually say I don’t think this is a good idea and I wouldn’t recommend it for them.” Shapiro emphasized that the risk of permanent side effects is “so, so rare. I’ve never seen it in a patient, and I’ve treated thousands of patients,” he said.