Testosterone is a sex hormone produced by the testes, the same reproductive gland that produces sperm. Testosterone plays an important role in puberty and in healthy sexual and reproductive functioning. Women also produce small amounts of testosterone. Supplementation is indicated for men with little or no testosterone production due to conditions such as pituitary gland dysfunction or testicular damage. Although testosterone gel may have benefits, side effects are possible.
Acne
Acne affects approximately 8 percent of testosterone gel users, according to Drugs.com. Testosterone gel can cause new acne to develop, or it may worsen existing acne.
Enlarged Prostate
Testosterone therapy causes enlargement of the prostate gland in 12 percent of users, Drugs.com says. Signs of an enlarged prostate include a weak urinary stream, urinary hesitancy and getting up at night to urinate. Testosterone therapy can also cause spontaneous and prolonged erections, testicular disorders, a low sperm count, reduced amount of ejaculate and testicular atrophy. An elevated prostate specific antigen, or PSA, level is also a possible.
Headache
Testosterone gel users can experience headache as a side effect of therapy. Other central nervous system side effects may also occur, such as depression, hostility, anxiety, difficulty sleeping, increased or decreased sex drive, and mood swings.
Gynecomastia
Gynecomastia, or the development of breast tissue in males, occurs frequently, Drugs.com says. Gynecomastia may persist after testosterone treatment ends.
Heart Problems
A study evaluating testosterone supplementation to increase muscle mass in frail elderly men was brought to an early halt due to the development of serious heart problems, according to a July 8, 2010 issue of the "New England Journal of Medicine." Compared to a group of men not taking testosterone, the men in the study suffered from a much higher incidence of heart attacks and other serious heart conditions. Increased respiratory and skin problems were also seen. The study concluded that elderly men with chronic diseases and limited mobility are at increased risk for serious side effects from testosterone therapy.
Fluid Retention
Fluid retention and swelling, or edema, is a serious side effect of testosterone therapy in users with preexisting liver, heart or kidney disease. Edema may be secondary to the development of congestive heart failure, or occur on its own. Testosterone should be used with caution in these patients and in those with other disorders worsened by fluid retention, such as epilepsy or asthma, according to Wolters Kluwer Health.
Harm to Close Contacts
The FDA requires the manufacturers of testosterone gel, which is applied to the skin, to warn users of the possibility for serious adverse effects in children who have close contact with the users. Testosterone on the skin can be transferred to others whose skin comes into contact with the application site or with hands that are not washed well after application. Transfer can also occur via linens and towels. Reports of children exhibiting premature sexual development and aggression prompted the FDA to require the warning. Women who are exposed may develop acne, changes in body hair or other signs of masculinization.
