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Doctors analyze testosterone levels in two categories: total testosterone and free testosterone. Most testosterone is attached to a protein called sex hormone-binding globulin (SHGB). A small amount of testosterone is free, and a small amount attaches and detaches itself from a protein called albumin regularly. Any testosterone that is not attached to SHGB is considered free testosterone.
Testosterone levels vary greatly in men depending on a number of factors including age, body mass index and ethnicity. However, testosterone levels generally decrease in men over time, decreasing on average one percent every year after age 30.
Testosterone gels enjoy the status as some of the most popular new products in terms of sales. These prescription drugs come in packets or pumps. Depending on the brand of medication, men (and some women) apply gels to arms, armpits, abdomen or the inside of the thigh.
In men, testosterone gels may decrease sperm count and increase the risk of prostate cancer. Women and children should not come in contact with gels because they can cause serious side effects, including mood swings, skin conditions and diarrhea (see more below). These drugs can also harm unborn babies.
Testosterone also comes in an injectable liquid form. Like gels, these drugs help men who no longer produce enough testosterone, but they are also prescribed to stimulate puberty in young men with a delayed onset of adulthood. Some women take them to treat certain types of breast cancer. One type of injectable, Testopel, is a pellet injected into the skin.
Doctors typically give injections in their clinics. Historically, these kinds of supplements were also the most abused.
The FDA warns that Aveed can cause serious allergic reactions. The most serious is the onset of serious breathing problems immediately after an injection. Patients who use Aveed should wait 30 minutes after receiving an injection before leaving their doctor's office. Certain blood thinners, oral steroids and diabetes medications can interact with these drugs in a negative way.
While gels and injections make up the bulk of the current testosterone market, the drugs also come up in patches, creams, nasal gels, capsules and tablets, known buccal systems. For this drug specifically, buccal systems are applied to the upper gum of the mouth.
Marketed as an herbal remedy to increase testosterone levels, this supplement has little solid scientific backing for those claims. Possible side effects include breast enlargement, cholesterol changes, prostate problems, and interactions with some heart, blood pressure and diabetes medications.
A precursor hormone that can be converted to testosterone or estrogen in the body, DHEA is often marketed as a means of boosting testosterone and muscle mass. Research on those claims is inconsistent. Side effects may include breast enlargement, cholesterol changes and hair loss.
While there is some evidence that large doses can increase testosterone, taking zinc at doses high enough to be effective can have side effects, including elevated cholesterol, increased prostate cancer risk, and liver or kidney problems.
An amino acid hyped as a testosterone booster, this supplement has little evidence to back its claims and has been associated with side effects that include increased prolactin levels and breast enlargement, bloating, anxiety, headaches and confusion.
Drugmakers often try to increase profits by creating new, unproven uses to piggyback on existing FDA approvals, putting patients at risk by making misleading statements about the drugs’ safety and effectiveness for those unapproved purposes.
It appears makers of testosterone therapies put a new twist on this marketing scheme. Manufacturers like Eli Lilly & Co. and Abbott Laboratories are riding on the successful marketing of Viagra and other erectile dysfunction treatments to encourage relatively healthy men to try testosterone therapy.
Erectile dysfunction drugs like Viagra found success in marketing strategies that promise to restore male youthfulness and vitality. Now drugmakers are using a similar approach to persuade men to ask their doctors about testosterone replacement.
Websites and TV ads show middle-aged men longing to rejoin sporting activities and ask men if they’ve lost their energy. Direct-to-consumer marketing quizzes set men up to believe that natural signs of aging point to a testosterone deficiency.
Marketing efforts suggest decreased energy levels are caused by Low T rather than by aging or any number of other factors. Once this energy-Low T connection is made, consumers are persuaded to visit their doctors seeking Low T therapy to help them regain vitality.
Eli Lilly & Co., AbbVie and other testosterone product manufacturers face criticism for these and other tactics. They created a $1.6 billion market for testosterone replacement drugs, and critics are they haven’t done enough to inform consumers and doctors about potential risks. Drugmakers have a legal duty to warn consumers and doctors about any known risks associated with their drugs.