Healthy 26-year-old had penis numbness, orgasm problems from popular drug — even a year and a half after he stopped taking it

Not all medications are medical marvels — some may do more harm than good.

A 26-year-old man reported sexual side effects like orgasm troubles after taking a hair loss drug popular among millions of men, according to a new case study.

Even after discontinuing it, his symptoms persisted for a year and a half.

Finasteride is a prescription medication that addresses benign prostatic hyperplasia and male hair loss. It is one of only two treatments approved by the FDA for male pattern baldness.

Unfortunately, a bevy of side effects — including sexual dysfunction — have been reported by patients.

The new case study, published in the Journal of Psychosexual Health, shared that the unidentified man had been taking a 1-milligram dose of finasteride to treat his hair loss.

He stopped the medication after six months due to side effects such as reduced ejaculation, significant loss of sexual pleasure and genital hypesthesia, or a loss of sensation in the penis.

He finally sought medical attention when his symptoms persisted for 19 months after quitting the drug.

Although many men have stopped losing hair or experienced visible hair regrowth with finasteride, there are potential side effects like erectile dysfunction, reduced sperm count and depression.

And while rare, post-finasteride syndrome (PFS) is when severe sexual, neuropsychiatric or physical side effects continue indefinitely even after the medication is stopped.

This often includes anxiety, suicidal ideation, brain fog, depression, fatigue, insomnia, decreased libido and testicular pain.

The only FDA-approved versions of the medication are oral tablets sold under the brand names Proscar and Propecia.

The FDA issued an alert last year about the potential risks associated with compounded topical finasteride.

The FDA warning followed a Wall Street Journal report detailing the severe side effects men reported after acquiring finasteride through telehealth platforms.

None of the 17 men the WSJ spoke to believe they were adequately informed of the potential pitfalls, as telehealth service providers aren’t obligated to disclose side effects and other risks in their advertising.

Former US Army Sgt. Mark Millich said he experienced anxiety, dizziness and slurred speech before his sex drive plummeted and his genitals shrank.

Another man detailed a nine-month struggle with PFS, noting the ups and downs in his libido and a sharp, burning pain in his pelvic area.