Losing interest in sex is one of the harder things to say out loud. Most men I see about it have waited months, sometimes years. Many arrive with a theory already in place: their testosterone must be low.
Sometimes that theory is right. Often it is only part of the story. And sometimes it points in exactly the wrong direction.
Here is the pattern I see in clinic. One man has a borderline testosterone result and a partner he no longer feels close to. Another has a perfectly normal result, a new antidepressant and a job that leaves him exhausted. Both say the same words: "I just don't want it any more." Both expect a hormone answer.
Desire is not a single switch. Specialists describe three parts to it. There is drive, which is biological. There is motivation, which is psychological. And there is wish, which is shaped by culture, upbringing and your relationship. In real life the three are tangled together.
Testosterone matters for desire. But the European Association of Urology makes a point that surprises many people. How much desire you feel does not track neatly with your testosterone level, especially as men get older. A number on a lab report is part of the picture, not the whole of it.
That is why I don't treat low libido as a blood test with a patient attached. I treat it as a question about your body, mood, medicines and relationship. The blood test is one of the tools we use to answer it.
This page walks you through what low libido is, what usually causes it, how testosterone fits in, what a proper assessment looks like, and what can actually help. It is part of my wider guide to sexual health and wellbeing.
Low desire or a low mood about sex — what counts as a problem?
There is no "normal" amount of sexual desire. It varies between people, and it changes across a lifetime. A drop in interest is only a medical problem if it bothers you, or it is causing strain in your relationship.
Doctors use the term low sexual desire for this. When it is persistent and distressing, the formal name is male hypoactive sexual desire disorder. That means a lasting lack, or absence, of sexual thoughts, fantasies and wish for sex. The judgement always takes your age and your life into account.
One distinction matters a great deal. Is loss of desire the main problem? Or is it a knock-on effect of something else, such as trouble getting an erection or coming too quickly? In my experience, men who struggle with erections often start avoiding sex, and that avoidance can feel exactly like low desire.