Editorial
Written byMen's Health Istanbul Editorial Team
Medical reviewer (awaiting sign-off)Prof. Dr. Bülent Alıcı
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The short answer
Low testosterone most typically shows up in your sex life: a lower sex drive, fewer or weaker morning erections and difficulty getting or keeping an erection. Many men also notice tiredness, low mood, poorer concentration, less muscle strength and more body fat, although these symptoms have many other causes. Because the symptoms overlap with stress, poor sleep, weight gain and depression, low testosterone cannot be diagnosed from how you feel alone. Doctors confirm it with blood tests taken in the morning, repeated on a second day, alongside your symptoms.
Key takeaways
- The symptoms most closely linked with low testosterone are low sex drive, fewer morning erections and erectile difficulties.
- Tiredness, low mood and weight gain are common with low testosterone but have many other causes.
- Diagnosis needs both symptoms and repeated morning blood tests showing low levels.
- Genuine late-onset testosterone deficiency is less common than online adverts suggest.
What are the first signs of low testosterone?
For most men, the clearest signals are sexual. The European Male Ageing Study, a large study of men aged 40 to 79 published in the New England Journal of Medicine in 2010, looked at which symptoms genuinely tracked with low testosterone levels. Three stood out:
- Fewer morning erections. Waking with an erection becomes noticeably less frequent.
- Lower sex drive. Less interest in sex, fewer sexual thoughts, less initiating.
- Erectile difficulties. Erections that are harder to get or keep.
Men often describe the change as gradual rather than sudden: sex slipping down the list of priorities over months, without an obvious reason.
Does low testosterone make you tired?
It can. Clinical guidelines list tiredness, reduced energy, low mood, irritability and poorer concentration among the possible symptoms. Some men notice they lose muscle strength more easily or put on fat around the middle.
The difficulty is that these are some of the most common complaints in adult life. Poor sleep, long working hours, stress, depression, alcohol, an underactive thyroid, anaemia and weight gain can all cause exactly the same feelings. In the European Male Ageing Study, general symptoms such as fatigue were much less specific to low testosterone than the sexual ones.
How common is low testosterone?
Less common than advertising suggests. When the European Male Ageing Study defined late-onset testosterone deficiency strictly, as the three sexual symptoms together with a low blood level, it applied to only about 2% of men aged 40 to 79. Levels do tend to drift down with age, but in many men the bigger drivers are weight, long-term illness, certain medicines and sleep.
How is low testosterone diagnosed?
Both the American Urological Association and the Endocrine Society set out a similar approach:
- Symptoms first. A doctor asks about sexual function, energy, mood and general health.
- Morning blood tests. Testosterone is normally highest in the morning, so the test is taken early.
- A repeat test. One low result is not enough; levels vary from day to day, and a second test on another day is needed.
- Looking for a cause. Further hormone tests help show whether the problem starts in the testicles or in the brain's signalling, which changes how it is managed.
A single test from a gym, a supplement website or a home kit is not a diagnosis.
Does testosterone treatment help?
In men with confirmed deficiency, treatment can help some symptoms. The T Trials, published in 2016, studied men aged 65 and over with low levels and found modest improvements in sexual function and mood, but no benefit for vitality or walking distance. Treatment has side effects to monitor, and it suppresses sperm production, which matters for men who may want children. A doctor decides whether it is appropriate and how it is given.
For men with normal levels, testosterone is not a fix for tiredness or a low mood.
When to see a doctor
See a doctor if you have noticed a lasting drop in sex drive, fewer morning erections or erectile problems, especially together with tiredness or low mood. It is worth going even if testosterone turns out to be normal, because the same symptoms can point to other treatable conditions. Our male sexual health guide explains how these problems are assessed.
Questions men also ask
What time of day should testosterone be tested?
Guidelines recommend an early morning blood test, when levels are normally highest, and a repeat test on another day to confirm a low result.
Can low testosterone cause depression?
Low testosterone can be associated with low mood and low energy, but depression has many causes. A doctor will usually look at both rather than assume one explains the other.
Is low testosterone just part of getting older?
Levels tend to drift down gradually with age, but most older men do not have testosterone deficiency. Weight, illness, medicines and sleep often matter more than age alone.
Sources & further reading
- New England Journal of Medicine Identification of late-onset hypogonadism in middle-aged and elderly men (opens in a new tab) (2010) Wu FCW, et al.
- Journal of Urology Evaluation and Management of Testosterone Deficiency: AUA Guideline (opens in a new tab) (2018) Mulhall JP, et al.
- Journal of Clinical Endocrinology & Metabolism Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline (opens in a new tab) (2018) Bhasin S, et al.
- New England Journal of Medicine Effects of Testosterone Treatment in Older Men (opens in a new tab) (2016) Snyder PJ, et al.
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This article is general health information. It does not replace an individual medical consultation, examination or diagnosis. Read our editorial policy and medical review policy.
