WARNING: This story discusses depression, suicide and suicidal ideation.

Two months ago, at his best friend's wedding, Andre Eid was doing a last-minute run-through of his speech when he felt a sinking feeling in his stomach.

"I was like, f***, I really hope I don't get the urge to panic. If I do, it's all on camera and I've f***ed up this whole wedding," he says.

The 28-year-old says this never would have happened three years ago.

"I was the guy who had charisma; I would carry the room," Andre says.

Finasteride has been on the market for hair loss since the 1990s. (ABC News: Rachel Clayton)

"I was a very extroverted person socially, but it's now accompanied with this anxiety."

Andre believes the change can be attributed to finasteride, a hair loss medication he used for three weeks in 2022.

The drug works by inhibiting the conversion of testosterone to the hormone dihydrotestosterone (DHT).

DHT is responsible for shrinking hair follicles, which can lead to baldness.

For the majority of users, finasteride is safe and effective, but a vocal minority say the drug can cause serious, long-term side effects.

Andre is one of half a dozen Australian men who have told Background Briefing the side effects of finasteride were not properly explained to them, and they are now paying a heavy price.

When doctors would not take his symptoms seriously, Andre turned to social media. (ABC News: Liam Patrick)

Some patients say they were never warned about side effects

Andre was prescribed topical finasteride when he was 25 from Ashley & Martin, a hair loss company he knew from television ads.

"I left that place thinking this is great, I'm sorted. I've tackled it early," he says.

But his elation quickly turned sour.

Within a few weeks, his nipples enlarged, he felt numb, tired and sexually muted.

"When I reached the point of climax, I realised that there was no pleasure. It was very bland."

Andre cancelled his prescription and threw away the remaining medicine.

Andre does not have a lot of hope a solution to his symptoms will be found. (ABC News: Liam Patrick)

But instead of improving, he says he developed psychiatric side effects like anxiety. His sexual symptoms worsened, too.

In a statement, Ashley & Martin said patients were provided with a treatment agreement that detailed potential adverse m