Millions of men around the world are using testosterone therapy to treat many symptoms that accompany aging in men, including erectile dysfunction, weight gain, and depression, but does this treatment even work? Some are casting doubt on that idea.

Researchers at Brigham and Women’s Hospital in Boston conducted one of the largest double-blinded studies of such therapies ever, and they have found some unfortunate results for the men who are taking testosterone treatments, according to a Huffington Post report.

A team led by endocrinologist Dr. Shalender Bhasin gave testosterone gel or a placebo to 306 men over 60, all of whom had either low or normal levels of testosterone. They did this every day for three years, and found that those who got testosterone had no improvement in sexual function or quality of life than those who got the placebo.

The findings indicate that increasing testoterone levels above the lower limit of the normal range doesn’t improve sexual function.

Still, that doesn’t mean it doesn’t work for men who have extremely low testosterone due to testicular or pituitary issues. Bhasin said that there was no question it works in those cases, according to the report.

Instead, the findings show that middle aged and older men who want to solve more minor problems when they are slightly in the lower-than-normal range probably won’t benefit at all.

It’s a multibillion dollar industry that has catered to men seeking to solve problems in the bedroom and with other aspects of their lvies as they get older. Pharmaceutical companies have been convincing relatively healthy men that they need these supplemental hormones, when in reality it’s not really helping, the findings indicate.

There was some silver lining to the study for testosterone users: it’s at least not harmful for the heart, indicating that earlier studies that said such therapy could result in a higher risk of cardiovascular problems or a heart attack may not have been accurate.