The causes and symptoms of low testosterone

man running male fertility


Low testosterone, what’s the deal? We’re all probably aware that testosterone plays an essential role in making a baby. But how much do you know about this important male sexual hormone? And what can the impact of low testosterone be on your fertility and general health? 

Let’s start with the basics. Testosterone is a hormone produced in your testicles. It kicks in properly around puberty and is responsible for things like hair and height growth, increased muscle mass and all those annoying random erections you get during school years. 

Testosterone also stimulates sperm production as well as a man’s sex drive – hence why it is so important infertility. Read more about this in our blog article “Testosterone And Sperm Quality”.


Low testosterone – what causes it?


There are a few reasons that can be behind low testosterone – aka low T. 

One is age. We talk a lot about the decrease of female fertility after a certain age – but men are not immune to the tick of the biological clock. On average, testosterone actually decreases by around 1% each year after thirty,

However, there are a bunch of other things that can contribute to low T including injury, illness and hormonal imbalances. As there can be various causes it’s important to understand the signs you should be aware of – and when to reach out to your doctor. 


Low testosterone  – the symptoms


Low T and your sex life 


Noticeably low sex drive


It’s understandable if you’re not always up for sex, but if you’re noticing that your sexual desire is seriously plummeting, it might be a sign of low testosterone. Our sex drive fluctuates naturally all the time – if you’re tired, stressed or ill, or if your relationship is going through a rough patch, you’re less likely to be up for it. 

But when low sex drive is down to low testosterone, it tends to be noticeable. You may find yourself unable to get in the mood, even if everything else is great or that you are struggling to find the desire to do it in general, rather than occasionally. 


Difficulty with erections


But what if you want to have sex but have difficulty rising to the occasion? Difficulty with erections – or erectile dysfunction – is a key sign of low T. Testosterone alone doesn’t make erections happen, but its job is to stimulate receptors in the brain that makes nitric oxide. 

What’s nitric oxide I hear you ask. Nitric oxide is a molecule that helps trigger a chemical chain reaction that leads to an erection. If you’re dealing with low testosterone, you may have difficulty achieving an erection prior to sex, or in general (like when you’re sleeping). 

However, Low T is only one of the factors that contribute to erectile dysfunction and research is a bit inconclusive about whether testosterone replacement therapy can help. A review of studies that looked into the benefit of testosterone therapy for erectile dysfunction found that only half saw improvement. So whilst difficulties with erections can be a sign of low T, it may also be linked to other conditions or lifestyle factors including stress, smoking, diabetes or thyroid problems. 





Low T and your body 


Hair loss


Just like testosterone kick starts that body hair growth spurt during puberty, losing hair can be a sign that your testosterone levels are decreasing. Of course, balding is a natural part of ageing for many guys – and it might be something you’ve inherited. However, men with low T may lose the hair on the face and the body, as well as their head. 


Loss of muscle mass & increased body fat


In the same way, you grow body hair during puberty, this is also the time many guys fill out with muscle – and that’s largely down to testosterone. Men with low T might notice that their muscle mass goes down – although it may not be evident in the gym, as sources show that it doesn’t necessarily affect strength or function. 

Whilst muscle mass can go down, your body fat can go up. Of course, this can also be down to things like diet and lack of exercise, but if testosterone is the culprit, you might notice fat growing more around your chest. This is believed to happen if you have an imbalance between estrogen and testosterone. 


Smaller testicles


Whilst the size of your balls doesn’t always correlate with infertility or low T, the hormone does contribute to the development of the penis and testicles. Lower levels can contribute to smaller testicles – and sometimes penis – compared to a guy with average testosterone levels. 


Low T and your mental health 


Mood changes 


Something that’s interesting to note – is that many symptoms of low T are similar to depression. Men with low testosterone often report increased irritability and low mood and lack of focus. With any hormonal imbalance, mood swings can be common and research has even shown that low testosterone can contribute to mental health issues. If you’re struggling with your mental health in any way, never be afraid to reach out to your doctor. Even if low testosterone isn’t the cause, it’s important that you find out what is and get help.  




Men with low T may also experience a drop in energy levels or extreme fatigue. Try to ensure you’re getting at least 7-8 hours of sleep a night and exercising regularly, but if you find you’re still really tired – or don’t even have the energy to work out – it could be a sign your testosterone levels aren’t where you want them to be.  




Just like testosterone levels decline with age, so does brain function – especially memory – and doctors have theorised that there could be a link. Some small research studies have indicated that giving men a testosterone supplement can improve memory for men with low levels. 

Many of these symptoms can be attributed to things other than low testosterone, so that may not be the cause, but it’s always worth investigating, so speak to your doctor if you notice any of these symptoms. 


Low T and your fertility 


 If you do have low testosterone, don’t panic – this doesn’t always mean your fertility is going to be impacted. 

The fact is, that men with low T can still in theory produce healthy sperm and some men with high testosterone will not be able to. It is not the only hormone involved in sperm production, and there’s a delicate balancing act going on in there (read more about that here) so don’t automatically assume the worst. 

The main concern with low T is that it could reduce your sex drive and your ability to maintain an erection – but there is plenty of medical help available for symptoms like that. As with everything, when it comes to your fertility, being proactive is the best course of action, so don’t be afraid to investigate your testosterone levels if you’re concerned – it will give you plenty of time to get the support you need for your journey to fatherhood. 


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