Your teen years may be behind you, but that doesn’t always mean so is acne, especially if you’re a woman. The usual treatment for stubborn adult acne is a course of oral antibiotics. However, the acne usually comes back and one course can lead to many—which ends up being a lot of antibiotics and is very bad for your health. There is a better option, according to a new study.

Although dermatologists as a group prescribe more antibiotics than any other kind of doctor—especially for repeated flare-ups of acne—some dermatologists have been successfully treating their female acne patients with the blood pressure drug spironolactone (Aldactone). Besides being a diuretic (a drug that removes water from the body), which is partly why it’s prescribed for high blood pressure and heart failure, spironolactone blocks the effects of the hormone androgen, a primary underlying driver of acne in women. Although androgen is chiefly a “male” hormone, women also have some in their bodies.

Spironolactone is not FDA-approved to treat acne, but dermatologists know it works in women with acne and prescribe it for that purpose “off label,” usually only after multiple rounds of antibiotics have failed. (Blocking androgen in men does not help acne and may result in larger breasts.)

Researchers at Perelman School of Medicine in Philadelphia wondered whether spironolactone should be the go-to first treatment when a drug is needed to treat a woman’s acne. So they looked at six years of medical records of more than 6,000 women who had taken spironolactone for acne and more than 30,000 women who had taken tetracycline, the antibiotic most commonly prescribed for acne.

Results: Tetracycline and spironolactone were equally effective. Meanwhile, their safety profiles—at least as far as how they’re used to treat acne—are not equal. Long-term use of oral antibiotics, including tetracycline, has been linked to lupus, inflammatory bowel disease, colon cancer and breast cancer. In contrast, side effects of the low doses of spironolactone that are prescribed for acne, such as breast tenderness, gastrointestinal upset, menstrual irregularity, fatigue and headache, are mild and temporary.

Important: Before starting spironolactone, women must first have blood tests, including one to check that their potassium levels are normal. Because the drug causes water loss (you’ll urinate more), it can raise potassium levels in the body. Although dangerously high potassium levels are rare, patients need to be vigilant about staying hydrated.

Also, spironolactone doesn’t work as quickly as antibiotics do. For women with acne, starting treatment with both drugs and then stopping the antibiotic (so it is not used long-term) is one way around this.

Without major studies showing that it works for women’s acne, the FDA has not yet approved spironolactone for that condition. The researchers said that they hope their work will help change that.

Bottom Line: If you’re a woman struggling with acne and your doctor is writing out yet another scrip for antibiotics, ask whether spironolactone might be better. You can bring this article with you.