Can low testosterone cause fatigue? What should I do about it?


What does testosterone do?

Testosterone is a hormone produced mainly by the testes in men. Women produce testosterone from their ovaries, but at much lower volumes. Testosterone production increases significantly when a boy reaches puberty, and plateaus until around the age of 30, where it may gradually begin to decline.

In an adult man, low testosterone is typically defined as anything under 300 ng/dL. Ng/dl is nanograms of the hormone per deciliter of blood, which is typically how testosterone is measured in blood tests. Testosterone variance is normal in men, with normal levels stretching anywhere between 300 and 1000ng/dL. When testosterone levels dip below the lower bounds of that normal range, men may begin to experience various symptoms which can be uncomfortable to deal with.

Testosterone plays many important roles in the body, including increasing sex drive, promoting bone density and muscle mass, and distribution of body fat. It is also involved in the production of sperm and red blood cells. Testosterone is known to affect men’s moods, and while high levels can promote energy, drive and aggression, low levels can leave men feeling sluggish, moody and depressed.


Can fatigue be caused by low testosterone?

There are quite a few symptoms of low testosterone levels in men, not all of which are experienced by every man with low levels. A very common symptom however, is fatigue. 

Fatigue involves a persistent feeling of tiredness or lack of energy. It isn’t the same as feeling occasionally tired. Other symptoms of fatigue may be difficulty concentrating, lack of motivation, low sex drive, and even depression. Being sleepy may be a symptom of fatigue, but it’s not the same thing. If you can’t shift the feeling of tiredness, even with proper sleep and regular rest, it may be fatigue.

Fatigue is a common symptom of many medical conditions , but also a natural result of some lifestyle choices, such as lack of exercise or poor diet.


What else can fatigue be caused by?

Feeling fatigued doesn’t necessarily mean you have low testosterone, and may also be caused by conditions such as:

  • Anemia.
  • Sleep apnoea.
  • Underactive thyroid.
  • Coeliac disease.
  • Chronic fatigue syndrome (CFS).
  • Diabetes.
  • Glandular fever.
  • Depression.
  • Anxiety.
  • “Long COVID”


Are fatigue and erectile dysfunction linked?

Possibly, but not in every case. For a man to achieve an erection, he has to become aroused. Fatigue as a result of low testosterone, or even fatigue in general, can inhibit a man’s “sex drive”, making it difficult to become aroused or sex-motivated in the first place.

Experiencing low sex drive and erectile dysfunction are also two symptoms of low testosterone levels, and although there are other factors at play, testosterone-related-fatigue is a major one. If low testosterone is the cause of these symptoms, and there are no other health-related causes, treating the testosterone deficit should treat the fatigue and ED. 11% of erectile dysfunction cases are caused by hormone imbalances in men, namely high prolactin or low testosterone levels.


What should I do if I feel fatigued?

Your first step should be to go and see your doctor. A quick and simple blood test can usually identify the source of your fatigue, and depending on the condition there may be a simple fix.

Your blood test will show your doctor your testosterone levels. If your levels are under 300 ng/dL your doctor might prescribe you medication to raise testosterone levels, such as intramuscular testosterone injections, testosterone patches or topical testosterone gel.

They are however, also likely to suggest lifestyle changes. There are many aspects of your lifestyle that may have a significant effect on your body’s ability to produce testosterone, and they work without potential side effects and risks of hormone therapy.

Lifestyle changes that encourage testosterone production include:

  • More exercise (particularly heavy weight lifting).
  • Eating a healthy and balanced diet.
  • Minimising stress.
  • Taking daily vitamin D supplements.
  • Getting high-quality sleep.
  • Reducing alcohol and/or drug intake.