Gynecomastia Causes: What Causes Breasts to Form in Males?

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Because this is categorized as an endocrine condition, gynecomastia causes have to do with hormonal balance and the function of the endocrine system. As men age, hormonal changes occur. Testosterone levels may decrease, resulting in the formation of firm breast tissue. Some diseases that affect the endocrine system also cause this condition. Adrenal gland tumors, hypogonadism, hyperthyroidism, pituitary tumors, kidney disease, testicular tumors and liver failure all have the potential to cause gynecomastia.

Other gynecomastia causes include the use of prescription medications, illegal drugs and alcohol. Some drugs damage the endocrine system, which is what causes endocrine changes to occur. Examples of drugs that contribute to the development of gynecomastia include chemotherapeutic agents, anti-anxiety drugs, tricyclic antidepressants, drugs used to control AIDS, antibiotics and some of the drugs used to treat heart disease. Anabolic steroids, marijuana, heroin and amphetamines can also cause this condition.

Signs and Symptoms

The major sign of gynecomastia is the formation of firm breast tissue on a man or a boy. It’s important to note that the formation of fatty tissue is not a case of gynecomastia. Instead, it’s called psuedogynecomastia, and it occurs when fat deposits form on the chest tissue. Patients with this condition may also experience tenderness in the breast area.


Diagnosis of this condition starts with a physical examination and a review of your medical history. During the examination, your doctor will ask you when you first noticed the firm tissue and ask about other symptoms, such as tenderness. You will also discuss any recent illnesses, the use of prescription medications and other health issues. Based on the results of the physical examination, your doctor may make a diagnosis of gynecomastia or conduct further testing. Because this condition is common in male teens, teenage boys will most likely not need additional testing. If the condition occurs in a very young boy or an older man, the doctor might order lab tests to check hormone levels.


In many teenagers, the firm breast tissue goes away without intervention within two or three years. In the meantime, some doctors want to check the breast tissue and measure it every few months. For those who have gynecomastia related to the use of medications, stopping the medication may be enough to make the tissue go away. If a medical condition caused the formation of the firm tissue, your doctor will treat the underlying cause of the gynecomastia. Surgery is only needed in rare cases.

Cancer Concerns

Those who have male breast cancer risk factors, bloody discharge from the nipple or any other unusual breast symptoms, along with the development of new breast tissue, should make an appointment with a doctor for an examination and diagnostic testing. Gynecomastia does not cause bloody discharge or other possible cancer symptoms.


eMedicine: Gynecomastia Gynecomastia: When Breasts Form in Males

MedlinePlus: Gynecomastia

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