Symptoms of low testosterone in men under 30 include erectile dysfunction, decreased libido or sexual activity, infertility, and hair loss.

When you think of declining levels of testosterone, you might think of middle-aged or older men. But men under 30 can also experience low testosterone, or “low T.”

According to the Mayo Clinic, testosterone levels tend to peak in men during adolescence and early adulthood. Those levels typically decline by about 1 percent each year, starting around age 30. But in some cases, you may experience declining testosterone at a younger age.

Low T is a medical condition where your body doesn’t produce enough of the hormone testosterone. Both men and women produce testosterone, but it’s called the “male hormone” because men produce a lot more of it. It’s critical for many male characteristics, including the maturation of male sex organs, sperm development, muscle mass development, voice deepening, and hair growth. Low T can cause a variety of symptoms, including erectile dysfunction, infertility, muscle mass loss, fat gain, and balding.

If you think you might be experiencing low T, make an appointment with your doctor. In some cases, it is caused by unhealthy lifestyle habits that you can change. In other cases, it is caused by an underlying medical condition that requires treatment. Your doctor can help you identify the cause of your symptoms and learn how to manage them.

Some advertisements for testosterone replacement products may lead you to believe that simply feeling tired or cranky is a sign of low T. In reality, symptoms tend to be more involved than that. Regardless of your age, low T symptoms can include:

  • erectile dysfunction, or problems developing or maintaining an erection
  • other changes in your erections, such as fewer spontaneous erections
  • decreased libido or sexual activity
  • infertility
  • rapid hair loss
  • reduced muscle mass
  • increased body fat
  • enlarged breasts
  • sleep disturbances
  • persistent fatigue
  • brain fog
  • depression

Many of these symptoms can also be caused by other medical conditions or lifestyle factors. If you’re experiencing them, make an appointment with your doctor. They can help you identify the underlying cause and recommend a treatment plan.

Low T is less common among men under 30, but it can still occur. Contributing factors include:

  • high cholesterol levels
  • high blood pressure
  • being overweight or obese
  • drinking excessive amounts of alcohol
  • using illegal drugs
  • using anabolic steroids
  • taking certain prescription medications such as steroids and opiates, especially in excess

Some cases of low T may be linked to other medical conditions, such as:

  • hypothalamic or pituitary disease or tumors
  • injuries, tumors, or other conditions affecting your testicles including inflammation related to childhood mumps
  • inherited diseases, such as Kallman’s syndrome, Prader-Willi syndrome, Klinefelter syndrome, or Down syndrome
  • diabetes, liver disease, or AIDS
  • cancer treatments such as radiation and chemotherapy

If you suspect that you might have low T, make an appointment with your doctor. They can use a simple blood test to determine your testosterone level.

If your doctor finds that your testosterone level is lower than normal, they may order additional tests or do an exam to investigate why. Your treatment plan will depend on your diagnosis and medical history. Your doctor may recommend lifestyle changes or testosterone replacement therapy.

You should always talk to your doctor before taking new medications, including testosterone replacement therapy and supplements. According to research published in PLOSOne, testosterone therapy may increase your risk of heart attack, particularly if you already have heart disease. Your doctor can help you understand the potential benefits and risks of different treatment options.