What are the signs and symptoms of low testosterone?

The most common signs of low testosterone are low sex drive, fatigue, loss of muscle and strength, low mood, and difficulty concentrating — usually several together rather than just one.

The symptoms tend to fall into three groups. Sexual: reduced libido, weaker or fewer erections, and fewer morning erections. Physical: persistent tiredness, loss of muscle and strength, increased body fat (especially around the middle), reduced stamina, and over time lower bone density. Mental and emotional: low mood or irritability, brain fog, poor motivation, and disrupted sleep. Many men also notice thinner body or facial hair.

The catch is that these symptoms are non-specific — they overlap with stress, poor sleep, depression, thyroid problems, and simply being run-down. That's exactly why symptoms alone can't diagnose low testosterone; they tell you it's worth investigating, and a morning blood test confirms it.

What to do: if several of these ring true — particularly low libido plus fatigue and lost strength — it's worth a morning blood test (total and free testosterone, plus SHBG). Meanwhile, the lifestyle basics that raise testosterone (sleep, losing excess fat, strength training, fixing deficiencies) are worth starting regardless. If symptoms are clearly affecting your life, see your doctor.