The symptoms that point most strongly towards low testosterone are sexual: lower sexual desire and fewer spontaneous or morning erections. Fatigue, low mood, reduced strength and increased body fat are common but have many other causes. Symptoms alone are not enough; blood testing is needed for confirmation.
What symptoms can occur with low testosterone?
Sexual
Persistently reduced sexual desire, fewer spontaneous or morning erections and, in some men, erectile dysfunction.
Physical
Reduced muscle mass or strength, increased body fat and less body hair. Longer-standing deficiency can also contribute to anaemia or lower bone density.
General
Fatigue, lower motivation, difficulty concentrating or mood changes. These are very non-specific symptoms.
Source: EAU 2026.
Which symptoms are more suggestive?
The EAU considers sexual symptoms more specific for late-onset hypogonadism. A persistent fall in sexual desire or spontaneous erections carries more weight than isolated fatigue, although neither proves the diagnosis.
Erectile dysfunction may also justify cardiovascular and metabolic assessment when the context suggests it, because vascular, medication-related and psychological causes are common alongside hormonal causes.
Why is tiredness not enough?
Fatigue, poor concentration and low mood can be caused by sleep apnoea, depression, anaemia, hypothyroidism, diabetes, chronic illness, alcohol, medicines or simply too little sleep. Assuming testosterone is the cause can delay finding the real problem.
What physical changes can occur with longer-standing deficiency?
Longer-standing testosterone deficiency can be associated with loss of lean mass, increased body fat, lower bone density and anaemia. These findings are useful only when they fit the history and blood tests; they are not a home test for low testosterone.
Can an online questionnaire tell me if my testosterone is low?
No. Questionnaires can organise symptoms but do not reliably distinguish who has biochemical deficiency. A high score does not prove hypogonadism and a low score does not exclude it. Confirmation requires clinical assessment and appropriately timed blood tests.
When does it make sense to speak to a doctor?
Seek medical advice if symptoms persist, are new, worsen or affect daily life. It is particularly reasonable when sexual symptoms occur alongside testicular or pituitary history, opioid or anabolic-steroid use, fertility difficulty or an illness that may affect hormones.