Men's Sexual Health

How Do You Know If You Have Low Testosterone?

Linda Girgis | MD

Medically reviewed by Linda Girgis | MD, Girgis Family Medicine on August 21st, 2026.

Low testosterone symptoms include fatigue, decreased libido, erectile dysfunction, and reduced muscle mass. Blood tests measuring total testosterone levels below 300 ng/dL typically indicate low testosterone, though symptoms matter more than numbers alone. Common signs include difficulty building muscle, increased body fat, mood changes, and poor sleep quality. Men over 40 experience a natural 1-2% annual decline in testosterone production. Additional symptoms may include brain fog, irritability, and decreased motivation. If you're experiencing multiple symptoms, consult a healthcare provider for proper testing and evaluation of your hormone levels.

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