10 Medicines That Can Give You Manly Breasts

So here’s a fun one. You are a guy. You take a prescription for something perfectly reasonable – blood pressure, hair loss, heartburn – but after a few months your chest starts to look a little… different. It’s gynecomastia, the medical term for enlarged male breast tissue, and one of the more unpleasant side effects that no one seems to warn you about at the pharmacy.

While the condition can resolve on its own, an increasing number of men are turning to plastic surgery to manage it. It appears most often during hormonal periods such as puberty, but a surprising number of daily medications can also trigger it. Here are 10 of them.

1. Risperidone (Risperdal)

Of all drug-induced gynecomastia cases reported to the FDA, risperidone — an antipsychotic for schizophrenia and bipolar disorder — accounted for over 80 percent of the total. It blocks dopamine receptors, which spikes prolactin, which suppresses testosterone, which lets estrogen run the show. It is the ideal hormonal environment for breast tissue to grow.

2. Spironolactone (Aldactone)

Spironolactone treats high blood pressure and heart failure by helping your body excrete excess fluid. It also, less helpfully, pushes androgen away from its receptors and increases estrogen production at the same time. One drug, two hormonal problems.

3. Finasteride (Propecia, Proscar)

Prescribed for hair loss and enlarged prostate, finasteride works by blocking testosterone from converting to DHT. Helpful. Except when you mess with DHT, it can throw your hormone balance sideways, and clinical trials found gynecomastia in 4.5 percent of users compared to 2.8 percent on placebo. Small number. It would still have been nice to know.

4. Anabolic steroids

The compounds bodybuilders use to get bigger can also make their breasts bigger—and not in the way you want. Synthetic testosterone floods the body with androgens, some of which are converted to estrogen. Enough estrogen, and breast tissue follows. The irony is almost poetic.

5. Bicalutamide & Flutamide (Casodex, Eulexin)

These drugs block testosterone and DHT from promoting prostate cancer cell growth. By interrupting the activity of testosterone, they allow estrogen to dominate and stimulate breast tissue growth. For men battling prostate cancer, it’s often a trade-off worth making — but worth knowing going into it.

6. Haloperidol (Haldol)

Used for schizophrenia and Tourette syndrome, Haldol works in the same basic way as risperidone – dopamine blockade, prolactin spike, testosterone suppression and breast development. Same frustrating result, different pill.

7. Ketoconazole (Nizoral)

Primarily prescribed for skin conditions such as ringworm and jock itch, ketoconazole has a less advertised effect further down the body. It inhibits the body’s production of testosterone. Lower testosterone tips the balance towards estrogen and your breast may become a little “fuller”.

8. Cimetidine (Tagamet)

This common GERD medication reduces stomach acid and also has weak anti-androgenic properties. It interferes with the liver’s hormone processing, allowing estrogen to accumulate. One study found that users had a gynecomastia risk that was more than seven times higher than non-users, and it scaled with dose.

9. Diazepam (Valium)

Prescribed for anxiety, muscle spasms and seizures, Valium calms the nervous system by boosting GABA. In some cases, it has been linked to gynecomastia through interference with hormone regulation, although the exact mechanism is still not fully understood. One of the less predictable on this list.

10. Metronidazole (Flagyl)

An antibiotic and antiparasitic agent for infections of the stomach, skin and reproductive system, Flagyl works by entering bacteria and damaging their DNA. It has also been associated with impaired testosterone synthesis and, in rare cases, gynecomastia. The science of exactly why is still incomplete, but the cases are real.

If you notice swelling or tenderness in your chest after starting any of these, talk to your doctor before stopping anything. Most are prescribed for real reasons, and there are often alternatives with fewer hormonal side effects.