What is testosterone?



Testosterone is one of the hormones needed for sexual development and is present in everyone. Testosterone is mostly made in the testicles, which are part of the male reproductive system. But small amounts are also made by the ovaries, which are part of the female reproductive system, and the adrenal gland. Testosterone is considered an androgen, which is a male sex hormone.

Testosterone helps strengthen bones and muscles. During male puberty, testosterone signals the body to lower the voice, grow facial hair, and develop male sexual characteristics. Testosterone is also one of the hormones needed by the testicles to make sperm.

Testosterone is also a medicine made in a lab. It may be prescribed by a doctor to treat medical conditions, such as when a person's natural level of testosterone is too low. This type of testosterone is also used in gender-affirming care.

What are some examples of testosterone?

Here are some examples of testosterone. For each item in the list, the generic name is first, followed by any brand names.

  • testosterone (Androderm, AndroGel, Delatestryl, Depo-Testosterone)
  • methyltestosterone (Android, Testred)

This is not a complete list of testosterones.

What are some cautions about taking testosterone?

Cautions about taking testosterone include the following:

  • Taking testosterone may cause symptoms of an enlarged prostate, such as trouble urinating.
  • Experts don't know for sure if taking testosterone affects the risk of prostate cancer.
  • Testosterone can lower your fertility while you're taking it.
  • Taking testosterone can cause your body to make too many red blood cells. This can cause blood clots and other problems, such as heart attack or stroke.
  • Taking testosterone can cause birth defects. If you could get pregnant and are taking testosterone, birth control is recommended.

Why is testosterone used?

Testosterone may be used to:

  • Increase testosterone levels when the body isn't making enough.
  • Improve sex drive.
  • Increase muscle mass.
  • Prevent bone loss.
  • Provide gender-affirming care.

Testosterone should not be used unless tests have shown that testosterone levels are low.

What are the side effects of testosterone replacement?

Side effects of testosterone replacement may include:

  • Your body making too many red blood cells. This may cause blood clots and other problems.
  • Headaches.
  • Blisters, itching, or redness on the skin under the testosterone patch.
  • Soreness in the breasts.
  • Symptoms of an enlarged prostate, such as trouble urinating.
  • Sudden, dramatic mood swings.
  • Hair loss.
  • Sleep apnea.
  • Acne.

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