Testosterone is a hormone made by the testicles. It is important for a man's sex drive and physical appearance.
Certain health conditions, medicines, or injury can lead to low testosterone (low-T). Testosterone level also naturally drops with age. Low testosterone can affect sex drive, mood, and changes in muscle and fat.
Treatment with testosterone therapy may help reduce symptoms.
How Testosterone Affects Health
Testosterone makes a man look and feel like a man. In a man, this hormone helps:
- Keep bones and muscles strong
- Determine hair growth and where fat is on the body
- Make sperm
- Maintain sex drive and erections
- Make red blood cells
- Boost energy and mood
Causes of Low Testosterone
Beginning around age 30 to 40, testosterone levels may start to slowly decrease. This occurs naturally.
Other causes of low testosterone include:
- Medicine side effects, such as from chemotherapy.
- Testicle injury or cancer.
- Problems with glands in the brain (hypothalamus and pituitary) that control hormone production.
- Low thyroid function.
- Too much body fat (obesity). Ask your doctor whether you need a test called free testosterone.
- Other disorders, chronic diseases, treatments, or infection.
Some men with low testosterone do not have any symptoms. Others may have:
- Low sex drive
- Problems having an erection
- Low sperm count
- Sleep problems such as insomnia
- Decrease in muscle size and strength
- Bone loss
- Increase in body fat
- Trouble concentrating
Some symptoms may be a normal part of aging. For example, it is normal to feel less interested in sex as you get older. But, it is not usually normal to have no interest in sex.
Symptoms may also be caused by other conditions, such as high blood pressure or diabetes. If any of these symptoms are bothering you, talk with your health care provider.
Your provider will likely have you get a blood test to check your testosterone level. You will also be checked for other causes of your symptoms. These include medicine side effects, thyroid problems, or depression.
If you have low testosterone, hormone therapy may help. The medicine used is man-made testosterone. This treatment is called testosterone replacement therapy, or TRT. TRT can be given as a pill, gel, patch, injection, or implant.
TRT may relieve or improve symptoms in some men. It may help keep bones and muscles strong. TRT seems to be more effective in young men with very low testosterone levels. TRT can also be helpful for older men.
TRT has risks. These may include:
- Enlarged prostate leading to difficulty urinating
- Blood clots
- Worsening heart failure
- Sleep problems
- Cholesterol problems
At this time, it is unclear whether TRT increases the risk of heart attack, stroke, or prostate cancer.
Talk with your provider about whether TRT is right for you. If you do not notice any change in symptoms after treatment for 3 months, it is less likely that TRT treatment will benefit you.
If you decide to start TRT, be sure to see your provider for regular checkups.
When to Call the Doctor
Call your provider if:
- You have symptoms of low testosterone
- You have questions or concerns about treatment
Male menopause; Andropause; Testosterone deficiency; Low-T; Androgen deficiency of the aging male; Late-onset hypogonadism
Allan CA, McLachlin RI. Androgen deficiency disorders. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 139.
Morgentaler A, Zitzmann M, Traish AM, et al. Fundamental concepts regarding testosterone deficiency and treatment: international expert consensus resolutions. Mayo Clin Proc. 2016;91(7):881-896. PMID: 27313122 pubmed.ncbi.nlm.nih.gov/27313122/.
U.S. Food and Drug Administration website. FDA drug safety communication: FDA cautions about using testosterone products for low testosterone due to aging; requires labeling change to inform of possible increased risk of heart attack and stroke with use. www.fda.gov/drugs/drugsafety/ucm436259.htm. Updated February 26, 2018. Accessed July 6, 2021.
Review Date 5/13/2021
Updated by: Brent Wisse, MD, Board Certified in Metabolism/Endocrinology, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.