Whether it’s on Facebook, TV or even the local newspaper, guys constantly are bombarded by advertisements about testosterone.

These ads promise to cure everything that ails you—from boosting energy to waning sexual performance to dwindling muscle mass—simply by taking a pill. But do these hormone supplements actually work to tackle low testosterone levels, or are they just all hype?

Testosterone levels in men peak at about age 30 and begins to slowly decrease every year from there.

“The normal levels of testosterone fall in males by approximately 1.6% per year,” says Dr. John-Paul Rue, an orthopedics and sports medicine surgeon at Mercy Medical Center in Baltimore. “When your testosterone falls to a certain level, this can lead to hypogonadism—decreased libido, diminished erectile quality, mood changes, depression, skin changes, decreased body hair, decreased bone mass.”

It’s natural to want to counter these effects. That’s where testosterone supplements—which are mainly aimed at men—can come into play. But many medical experts are skeptical about their effectiveness.

“The supplements are essentially touted to boost your body’s production of testosterone, improve sexual performance and help build stronger and bigger muscles,” Rue says. “But they can’t do that. It’s not that simple, and the evidence is not there to support these claims.”

Dr. William Miller, who specializes in hormone replacement therapy in New Jersey, says that there’s only one real way to boost testosterone that is actually proven to work.

“Supplements bought over the counter do not replace testosterone deficiency,” he says. “The only way to boost testosterone is by using true testosterone itself—by injection, creams or pellets.”

It’s important to distinguish between testosterone supplementation and testosterone supplements.

Testosterone supplements are vitamins or pills—often sold over-the-counter or available to purchase via phone—that are advertised to boost your body’s own testosterone production. Experts like Rue and Miller say you should be wary of taking these, especially without consulting a doctor, as they might cause more harm than good.

A 2010 study in The New England Journal of Medicine showed that some men older than age 65 had an increase in heart problems when they used testosterone gel. A 2014 Endocrinology Society study in rats concluded testosterone supplementation was a “potent tumor promoter for the rat prostate.”

Testosterone supplementation is when you take additional testosterone because of a medical condition caused by low testosterone levels.

Testosterone supplementation is done under the guidance of a medical professional who can offer advice and prescribe testosterone-boosting therapies.

Men with a history of prostate cancer shouldn’t take testosterone supplements or additional testosterone supplementation, as they might increase the growth of prostate cells and worsen the disease, Rue says.

“Once you start taking testosterone as a supplement, your body will actually slow its natural production of it. This can lead to a cycle of needing to maintain hormone treatment,” Rue says.

You can boost your testosterone levels naturally. Make sure you’re getting enough sleep, maintain­­ a healthy weight, stay active and decrease stress, Rue says.

“Your body’s testosterone level can adapt to your body’s needs,” he says. “If you are not active, your body doesn’t need much testosterone, but if you are physically active, your body signals for more testosterone to be made. If you’re stressed, your body may actually make less testosterone as a result.”