What Is Gynecomastia and Which Medications Can Cause It in Men?

As most people know, medications can cause side effects. For some men, this includes breast development (gynecomastia) — a side effect that can impact confidence and self image.

Here, we’ll talk about gynecomastia. We’ll cover what it is, which medications could cause it, and if you can take action to prevent or treat it.

What is “gyno” (gynecomastia)?

Gynecomastia, sometimes referred to casually as “gyno,” is the technical term for men developing enlarged breasts. Although it can be concerning to notice extra breast tissue, the condition is usually physically harmless.

Aside from being a somewhat rare medication side effect, breast growth can be a normal part of some stages of life. For instance, some newborn babies have breast development and leak a milk-like fluid from their nipples — regardless of sex. This breast development typically goes away as the baby grows.

Males can also experience some breast development during puberty. In fact, as many as 50% of males experience breast growth during this stage. But this breast development also usually goes away over time. 

Similarly, men over the age of 50 can experience breast development due to natural changes in hormone levels that can happen with age.

What are common symptoms of gynecomastia?

Swollen and tender breasts are the most common symptoms of gynecomastia. At first, you may notice a lump appear under the nipple. It may show up in one or both breasts. And it’s not unusual for one breast to be larger than the other.

Gynecomastia doesn’t usually represent a medical problem, although it can lead to unwanted appearance changes in the chest. However, if breast enlargement is accompanied by sudden pain or other concerning symptoms, it’s important to reach out to your healthcare provider for guidance.

Which common medications can cause gynecomastia?

Several medications that impact certain hormones in the body can cause gynecomastia. Some of these medications cause high levels of certain hormones, while others cause low levels of other hormones. The hormones most often at play are prolactin, estrogen, and androgens.

Some of these medications, which have been grouped together by the three main hormones involved, are discussed below. This isn’t an all-encompassing list. So talk to your healthcare provider or pharmacist if you are curious about whether the medication you take can cause gynecomastia.

1. High levels of prolactin

Both men and women naturally make prolactin, which serves many important roles in the body. But if a person’s prolactin levels are too high, they might have hyperprolactinemia. When this happens to men, it’s possible to develop symptoms like gynecomastia and erectile dysfunction.

Many things — including some health conditions — can elevate prolactin levels. The medications that can have this effect include:

• Haloperidol (Haldol)

• Risperidone (Risperdal)

• Chlorpromazine

• Fluphenazine

• Metoclopramide (Reglan)

• Methyldopa

• Certain antidepressant medications, like fluoxetine (Prozac), sertraline (Zoloft), and amitriptyline

• Opioid medications like morphine

2. Estrogen-like effects

When women develop breasts, estrogen plays a key role. This is also true for men. So anyone who takes a medication that raises the amount of estrogen in their body can experience gynecomastia as a possible side effect. 

Some medications that can have this effect are:

• Anabolic steroids like oxymetholone (Anadrol)

• Diazepam (Valium)

• Digoxin (Lanoxin)

• Phenytoin (Dilantin)

• Human chorionic gonadotropin (Novarel, Pregnyl)

3. Anti-androgen effects

Androgens are a category of hormones that include testosterone and dihydrotestosterone (DHT). Androgens play many roles in the body, including blocking the effects of estrogen.

However, some medications interfere with androgens like testosterone and DHT. When this happens, they’re not able to block estrogen’s effects as well.

As mentioned, estrogen is a key hormone for breast development in both women and men. So when estrogen is less restricted by androgens, a person may be more likely to develop gynecomastia. 

Medications that can have anti-androgen effects include:

• Spironolactone (Aldactone)

• Finasteride (Proscar)

• Cimetidine (Tagamet)

• Ketoconazole

• Certain medications that treat prostate cancer, like bicalutamide (Casodex) and flutamide

How likely are these medications to cause gynecomastia?

Some medications are more likely to cause gynecomastia than others.

For example, some medications that treat prostate cancer — like bicalutamide and flutamide — have a high risk of this side effect. Research shows that up to 70% of people taking these kinds of medications develop gynecomastia over time.

Another medication that’s known for causing this side effect is spironolactone. This medication is approved to treat multiple conditions, including swelling due to fluid buildup. In clinical trials, about 9% of men who took spironolactone developed gynecomastia. But other studies have found that it may affect up to 29% of men who take the medication.

Certain antipsychotic medications are also commonly linked to gynecomastia. This includes medications like haloperidol, fluphenazine, and risperidone. The specific level of risk is different for each medication.

In other cases, a medication may have some risk of causing gynecomastia, but the risk is low. For example, sertraline is a common antidepressant used to treat several mental health conditions. It’s been linked to gynecomastia, but this side effect is thought to affect less than 1% of people who take sertraline.

Your risk of developing gynecomastia also depends on your health, your medication dose, and other medications you take. For more detailed information, talk to your healthcare provider.

Which medications are used to treat gynecomastia?

Medications that treat gynecomastia are usually used off-label. If you want or need treatment, your healthcare provider can walk you through your options. These include:

• Dopamine agonists: These include medications like bromocriptine (Parlodel) and cabergoline, which may help manage high prolactin levels.

• Selective estrogen receptor modulators (SERMs): Tamoxifen, one type of SERM, helps lower the amount of estrogen in the breast tissue. So it can also help treat gynecomastia. Raloxifene (Evista) may also be an option.

• Androgens: DHT may help treat symptoms caused by little-to-no testosterone in your body. However, there’s not a lot of supporting evidence for their use.

Aside from medications, surgery is also a way to reduce breast size. But whether surgery, like medication, is an option will depend on your situation. Talk to your healthcare provider for more personalized advice.

Can I prevent gynecomastia?

Sadly, there aren’t a lot of well-researched ways to prevent gynecomastia.

Usually, the first step is to stop taking the medication that’s causing gynecomastia. And, over time, gynecomastia symptoms may resolve on their own. But it’s important that you only stop taking medication if your healthcare provider has given you the OK to do so.

However, if you’re being treated for prostate cancer, your cancer specialist may give you a medication to prevent gynecomastia. This could include tamoxifen or an aromatase inhibitor like anastrozole (Arimidex). Early research shows these medications may help prevent gynecomastia for people being treated for prostate cancer.

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Written by:

Nathan Williams, PharmD, RYT

Nathan is a clinical pharmacist, certified yoga instructor, and medical content writer. His clinical practice has spanned several sub-specialties including: emergency medicine, nutrition, and pediatrics.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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