Testosterone

Primary Uses in Males

Testosterone is primarily prescribed for men and boys who do not produce enough of the hormone naturally. This condition, known as hypogonadism, can be caused by issues with the testicles, pituitary gland, or hypothalamus. It is used to help with:

• Normal sexual development and function.
• Maintaining bone density and muscle mass.
• Treating delayed puberty in adolescent boys.
• Addressing impotence or other hormonal imbalances.

Uses in Females

In some cases, testosterone may be used in women to treat certain types of breast cancer that have spread to other parts of the body. It is typically used as a secondary treatment when other options have not worked.

Usage Limitations

Testosterone replacement therapy is intended for individuals with confirmed medical conditions that cause low hormone levels. It is generally not recommended to treat the natural decrease in testosterone that occurs as a result of aging.

The Role of Testosterone

Testosterone is a naturally occurring hormone known as an androgen. It is primarily responsible for the development and maintenance of male sex organs and secondary sex characteristics, such as a deep voice and body hair.

How Replacement Therapy Works

When the body does not produce enough testosterone naturally, testosterone medication is used to bring hormone levels back into a normal range. It works by acting as a direct replacement for the hormone the body is missing.

Once administered, the medication enters the bloodstream and binds to specific androgen receptors located throughout the body. This process helps regulate several physical functions, including:

• Maintenance of bone density and muscle mass.
• Distribution of body fat.
• Production of red blood cells.
• Regulation of sex drive and sperm production.

The medication does not cause the body to start producing its own testosterone again; rather, it provides a steady supply of the hormone to alleviate symptoms associated with low levels.

Common Side Effects

Many people using testosterone experience mild side effects. These may include:

• Acne or oily skin
• Breast enlargement or tenderness
• Increased body hair growth
• Mood changes, such as irritability or nervousness
• Headache
• Weight gain
• Pain, redness, or itching at the site of injection or application

Serious Side Effects

Contact a healthcare provider immediately if you experience any of the following serious symptoms:

• Signs of a blood clot, such as pain, swelling, or warmth in the leg
• Chest pain, shortness of breath, or sudden dizziness
• Difficulty urinating or a frequent need to urinate, especially at night
• Swelling in the hands, ankles, or feet
• Yellowing of the skin or the whites of the eyes
• Changes in mood, such as depression or anxiety
• Worsening of sleep apnea, including loud snoring or gasping for air during sleep

Long-term use of testosterone may also lead to a decrease in sperm count or changes in the size of the testicles.

Boxed Warnings

Certain testosterone products carry boxed warnings, which are the most serious warnings issued by the FDA:

• Secondary Exposure: Topical gels and solutions can transfer to others through skin contact. Exposure in children can lead to premature puberty, enlarged genitalia, and aggressive behavior.
• Injection Reactions: Some long-acting injectable forms carry a risk of pulmonary oil microembolism (POME) or severe allergic reactions shortly after administration. These must be given in a healthcare setting with a post-injection monitoring period.

Cardiovascular and Blood Clot Risks

Testosterone replacement therapy may increase the risk of heart attack, stroke, or cardiovascular death. There is also an increased risk of blood clots in the legs (deep vein thrombosis) or lungs (pulmonary embolism).

Cancer and Prostate Concerns

Testosterone is contraindicated in men with breast cancer or known or suspected prostate cancer. Treatment may worsen symptoms of an enlarged prostate (benign prostatic hyperplasia) and may increase the risk of developing prostate cancer.

Other Serious Precautions

• Blood Count Changes: Treatment can cause an increase in red blood cell mass (polycythemia), which requires regular monitoring of hematocrit levels to prevent complications.
• Liver Health: Certain formulations, particularly some oral medications, have been associated with serious liver injury or toxicity.
• Fluid Retention: Edema (swelling) may occur, which can be dangerous for individuals with heart, kidney, or liver disease.
• Sleep Apnea: Testosterone may worsen pre-existing sleep apnea, especially in those with obesity or chronic lung disease.

Pregnancy and Exposure

Testosterone is not for use in individuals who are pregnant or may become pregnant, as it can cause harm to a developing fetus. Women and children should avoid contact with application sites or unwashed clothing that has touched the medication.

Pregnancy

Testosterone is contraindicated for use during pregnancy. Exposure to this medication while pregnant can cause a female fetus to develop male physical characteristics, a process known as virilization. If pregnancy occurs during treatment, the medication should be discontinued immediately and a healthcare provider should be consulted.

For those using topical forms of testosterone, such as gels or liquids, it is important to prevent accidental skin-to-skin contact with others. Pregnant individuals should avoid contact with the application sites on another person's body to prevent the drug from being absorbed through their own skin.

Breastfeeding

The use of testosterone is not recommended for individuals who are breastfeeding. It is not fully understood how much testosterone passes into breast milk or what specific effects it may have on a nursing child. Due to the potential for adverse effects on the infant's development, healthcare providers typically advise against using this medication while nursing.

Topical Formulations

Testosterone is frequently applied to the skin or mucous membranes. These forms include:

• Transdermal Gels: Applied daily to the skin, often available in metered-dose pumps or individual packets.
• Transdermal Patches: Applied to the skin once every 24 hours.
• Topical Solution: Applied specifically to the underarm area.
• Nasal Gel: Applied inside the nostrils using a pump.

Injectable Formulations

Injections are administered into the muscle or under the skin:

• Intramuscular Injection: Administered by a healthcare provider or self-injected, typically every few weeks.
• Subcutaneous Injection: Administered under the skin, sometimes using an auto-injector device.

Oral and Buccal Formulations

• Oral Capsules: Swallowed whole, typically with a meal.
• Buccal System: A tablet-like system that is applied to the gums above the teeth.

Subcutaneous Implants

Testosterone is also available as small pellets that are surgically implanted under the skin by a healthcare professional. These pellets release the medication slowly over a period of several months.

FDA Approval and Indications

The U.S. Food and Drug Administration (FDA) has approved testosterone replacement therapy for men who have low testosterone levels due to specific medical conditions. These conditions include:

• Primary hypogonadism: Testicular failure caused by conditions such as genetic disorders, injury, or chemotherapy.
• Hypogonadotropic hypogonadism: Failure of the pituitary gland or hypothalamus to signal the body to produce testosterone.

The FDA has clarified that testosterone products are not approved to treat low testosterone levels caused solely by aging, as the benefits and safety for this use have not been established.

Boxed Warnings and Safety Communications

Many testosterone products carry a Boxed Warning, the FDA’s most serious type of warning. For topical gels and solutions, this warning highlights the risk of secondary exposure, where the medication is accidentally transferred to women or children through skin contact.

The FDA also requires manufacturers to include information about the potential increased risk of heart attacks and strokes in patients using testosterone. Healthcare providers are advised to only prescribe testosterone for patients with confirmed laboratory evidence of low testosterone caused by an underlying medical condition.

Regulatory Classification

Testosterone is classified as a Schedule III controlled substance under the Controlled Substances Act. This classification is due to the potential for misuse, abuse, and physical or psychological dependence. The FDA has issued safety communications regarding the serious risks associated with the abuse of testosterone and other anabolic androgenic steroids, which can lead to heart, liver, and mental health complications.