The symptoms of low testosterone are sometimes obvious, but they also can be subtle.

Testosterone levels decline naturally in men as they age. However, certain conditions can also lead to an abnormally low level. Symptoms of low testosterone include:
• Low sex drive (libido)
• Erectile dysfunction
• Fatigue and poor energy level
• Decreased muscle mass
• Body and facial hair loss
• Difficulty concentrating
• Depression
• Irritability
If a man has symptoms of low testosterone and tests show he has an abnormally low testosterone level, his physician may suggest treatment. Testosterone replacement therapy is available in several forms.