When a man turns 30 his testosterone levels peak, and with each passing year, testosterone levels diminish. At first, you might not notice any symptoms or side effects due to reduced testosterone and for some men, the most common symptoms never appear. However, for other men, the early signs of low testosterone levels can cause significant concern even in men who have no idea their symptoms are associated with decreasing testosterone.

What are the symptoms of low testosterone?

If you are experiencing one or more of the following symptoms, it may be time for you to get your testosterone levels tested:

• Fatigue: You feel tired more often than you used to. This is a common symptom of aging and increased stress, but it could also mean your testosterone levels have fallen.
• Poor sex drive: Testosterone is the sex hormone – so less testosterone means fewer a lower drive. 
• Erectile dysfunction: Believe it or not, low testosterone levels can affect erection strength and the ability to keep an erection. There are some who believe this is the natural life cycle in motion and that once a man’s testosterone levels reach a certain low, the body knows he will no longer produce children and thus production is “turned off.” 
• Depression: Low testosterone levels can affect your mood similarly to the way diminishing estrogen levels can affect moods in menopausal women.
• Weight gain: Testosterone plays an important part in metabolism. As your testosterone levels drop, you could notice increased fat stores and weight gain. Your doctor may ask you to adopt a healthier diet and exercise program before testing testosterone levels, in some cases. 
• Loss of strength: Testosterone is responsible for muscle growth and maintenance. If you have less muscle, you are bound to be less strong.
• Hot flashes: You may begin to have hot flashes when testosterone levels start to drop.

Decreased testosterone levels are a normal part of a man's aging, but there are ways to help. Many symptoms of low testosterone are often cured with hormone replacement therapy.