Scientists have discovered a potential method to predict which patients are most likely to experience sexual problems as a side effect of widely prescribed antidepressant medication. This breakthrough could help doctors personalise treatment for depression and improve patient outcomes.
The Challenge of SSRI-Related Sexual Dysfunction
Selective serotonin reuptake inhibitors (SSRIs), a common class of mood-stabilising drugs, are known to cause sexual side effects in a significant number of users. These can include a loss of libido, difficulties with arousal, and an inability to reach orgasm. These issues affect 40–70 per cent of patients treated with SSRIs for depression, according to research. Such side effects can severely impact self-esteem, relationships, and quality of life, often leading patients to stop taking their medication altogether, which risks a relapse of their depression.
A research team from the University of Copenhagen in Denmark set out to investigate if they could identify vulnerable individuals before they started treatment. They recruited 90 participants aged 18 to 56 who had been diagnosed with major depressive disorder but were not on medication. The group consisted of 66 women and 24 men.
Serotonin Levels Hold the Key
Before prescribing the SSRI escitalopram (sold as Cipralex in the UK) for an eight-week period, the scientists measured the participants' baseline brain serotonin activity using a simple electroencephalogram (EEG) scan. Serotonin, a crucial neurotransmitter for regulating mood, also plays a role in sexual function. The participants' sexual health was also assessed before and after the course of medication.
The findings, published in the Journal of Psychiatric Research, were revealing. The study concluded that individuals with higher pre-treatment levels of serotonin activity were more likely to develop sexual side-effects from the SSRI, particularly struggling to achieve orgasm.
After eight weeks, 65 per cent of patients reported some form of sexual problem linked to the drug. Doctors clinically assessed that 47 per cent had SSRI-induced sexual dysfunction, with 17 per cent (9 women and 4 men) describing their symptoms as severe and distressing. Overall, sexual function across the group declined by nearly a quarter (23 per cent).
Implications for Treatment and Ongoing Concerns
The researchers hope their work will encourage clinicians to consider measuring serotonin activity before prescribing SSRIs, allowing for more informed treatment choices. However, they acknowledged study limitations, including a gender imbalance in participants and the fact that women more commonly experience sexual dysfunction before starting antidepressants.
The research comes amid growing patient reports of post-SSRI sexual dysfunction (PSSD), a rare and contested condition where sexual issues persist long after stopping the medication. While not currently recognised by the NHS, a review in European Psychiatry notes 'growing evidence' for its existence. Advocacy groups report symptoms like genital numbness and a complete loss of libido.
The NHS does acknowledge sexual side effects during SSRI use. With antidepressant prescriptions rising—286,799 people aged 5 to 19 were prescribed them in 2024, up from 242,629 in 2016—finding ways to mitigate these distressing effects is increasingly urgent. Common SSRIs include citalopram (Cipramil), fluoxetine (Prozac), and sertraline (Lustral).
