Thammika Songkaeo knew instantly her husband was the one when they met in 2011.

The pair connected almost immediately and married two years later, welcoming a daughter into the world together.

Despite the deep emotional connection between them, Songkaeo always carried a troubling thought: her husband lacked interest in sex.

Upon meeting initially, her now ex-husband disclosed to Songkaeo about his low libido and erectile dysfunction, conditions he attributed to the use of finasteride, a medication prescribed to many men for hair loss prevention.

But she dismissed his problems as ‘something temporary’. When he struggled to perform in the bedroom, she got him to take Viagra.

Feeling apprehensive about being judged as a ‘sex addict,’ she refrained from confiding in her friends. However, this avoidance led to a sense of isolation, descent into depression, and eventually thoughts of suicide.

After seven years, she ended the relationship and filed for divorce.

Finasteride is sold by telehealth companies for as little as $30 for a month’s supply, with doctors saying it can prevent hair loss with little more than a pill a day.

The drug was originally developed for men with an enlarged prostate, but it has since become a popular hair loss treatment.

Around 2.6million men in the US take the drug.

It works by blocking the conversion of the male hormone testosterone into dihydrotestosterone (DHT), a compound thought to cause hair loss by shrinking hair follicles on the scalp.

But DHT is also crucial for sexual arousal, erectile function, and genital tissue health, and its reduction. 

While the drug shows a remarkable ability to promote hair growth, some men pay a steep price.

Some say the drug ruined their sex life, genitals and relationships — even long after they stopped taking it.

Songkaeo’s husband was prescribed the drug by an unnamed health clinic and took it before they met.

Doctors believe he was suffering from post-finasteride syndrome, a condition of persistent sexual, neurological, physical and mental adverse reactions in patients after they take finasteride to treat hair loss.

Her experience inspired her to write a book about a woman stuck in a marriage with an asexual husband in Singapore, titled: Stamford Hospital. It was launched in the US on April 15 this year.

Speaking to DailyMail.com, Songkaeo said her husband told her he was suffering from side effects of the drug after they became a couple.

‘We noticed… that there was something off about the physical intimacy,’ she said. ‘There just wasn’t the amount or intensity that there would be in my experience of a relationship.’

She added: ‘I thought it was something that could be overcome, as in I did not think it would be a lifelong thing — and from what I understood from my ex-partner there was no way for him to know if it would be a lifelong thing.

‘I thought, “maybe it will be ok. Maybe what it is will be ok “. It turns out, it was not ok.’

The couple met on the East Coast, and initially dated there before moving to Singapore together.

Songkaeo said in an interview with Moral Medicine — which raises awareness over harms caused by finasteride — that the couple tried Viagra to help with intimacy.

But after the birth of their daughter, she felt that what physical intimacy there was had now almost gone — and that there was just too little in the relationship.

‘I felt extremely lonely at that point,’ she told this website, ‘I’ve never felt that kind of loneliness in my life and never knew loneliness like that could be possible.

‘It felt like a loneliness that had no place on this Earth. It was very intense and harrowing.

‘And became like something that I could not live with, because it became very intense and harrowing.’

After speaking to her husband about their differences, the pair decided to amicably end the relationship.

Songkaeo said she experienced opposition from her family, who are from Thailand, when she revealed she was ending her marriage over intimacy problems.

But since the relationship was resolved, she and her husband have remained best friends — and now happily co-parent their daughter.

She would never, however, re-enter the relationship.

Finasteride works by blocking the enzyme that converts testosterone into DHT, which — according to the Cleveland Clinic — is typically found in the genitals.

About two to three percent of finasteride patients experience side effects, doctors say — with the most common being problems getting an erection, less interest in sex and problems with ejaculation, such as little or no semen.

Doctors tend to tell patients that these will subside after they stop taking the drug.

Giving other women advice on how to handle the issue, she said: ‘Letting compassion for both people guide the conversation leads to the best results. A conversation that is led by love and understanding for both people.

‘I really don’t think that people who suffer from post finasteride syndrome should be treated as anything other than victims of a very dangerous drug in terms of the side effects it can give.

‘At the same time, I don’t think that any partner needs to endure the effects as if they were inconsequential. 

She added: ‘I think that if both parties arrive at the conversation and carry the conversation with love, care, respect and empathy… even the way the relationship dissolves can become a beautiful part of a couple or ex-couple relationship.’