Fluctuations in your libido are expected, especially as you get older.

While lifestyle, medications, and stress can affect your sex drive, physiology can also be a factor. Testosterone, the hormone that boosts sexual desire, sperm production, bone density, and muscle mass, could be the culprit (1, 2, 3, 4, 5).

You might experience less interest in sex as the level declines, or you might not perform as well as you’d like sexually. A dip in sexual desire can cause depression and could affect intimate relationships. It’s natural to want to do something about it (6).

If you’re considering testosterone therapy to help improve your sex drive, here’s a look at the research.

Testosterone and estrogen are your primary sex hormones. Both men and women produce testosterone, but men make more. Alternately, a woman’s body creates more estrogen than a man’s (7).

Testosterone increases as a boy matures. It’s responsible for the maturity of sex organs, increased body and facial hair, bigger muscles, and deeper voices. It also promotes sperm production.

Testosterone levels vary throughout the day, usually peaking early in the morning. Additionally, levels fluctuate over your lifespan and decline every 10 years, usually 1–2 percent per year after age 30 (8, 9, 10).

This could mean you have less interest in sex later in life and possibly fewer firm erections, as well as softer muscle tone.

Aside from aging, there are several other causes that can result in lowered testosterone. They include:

Hypogonadism is a condition that occurs when the body doesn’t produce enough testosterone on its own. Testosterone replacement therapy is usually used to treat hypogonadism. However, it’s unclear whether supplements can help.

The Endocrine Society recommends offering testosterone therapy to people with symptoms of testosterone deficiency. In men over 65, treatment should only be initiated on an individual basis and after consultation with the person regarding risks and benefits. (11).

Furthermore, an analysis of 156 controlled trials between 1950 and 2016 where participants were given supplements didn’t find benefits for sexual, physical, and cognitive function, mood, or cardiovascular health.

But since the study also includes individuals without hypogonadism, the results may offer an unclear picture (12).

In fact, testosterone supplements might cause more problems than they solve. Studies have suggested a connection between supplements and heart problems. One found that some men over age 65 had increased heart problems when they used testosterone gel (13, 14, 15).

Another study involving a group of men under 65 who had a history of heart problems and a group of heart-healthy older men showed that both groups had a greater risk for heart attacks when taking testosterone supplements (16).

Furthermore, while there are contradictory findings, the use of testosterone replacement therapy may increase your risk for prostate cancer and cardiac issues (17, 18, 19).

Like other supplements and medications, testosterone therapy comes with risks and possible side effects. This is particularly true if you try to take it for normal aging rather than to treat a condition.

The effects that these supplements may have on your heart and prostate can lead to some potential issues. Complications include:

While low testosterone is a common cause of low sex drive in men, there are various other possible causes.

Psychological causes can contribute to low libido. These include:

In addition to low testosterone, various other physical causes can result in a decreased sex drive. Some of these reasons include:

Your healthcare provider can help you determine what’s causing your low libido. And they may recommend counseling if they believe psychological factors are contributing to it.

Testosterone therapy isn’t for everyone. There are also natural remedies available that you can try:

  • Get enough zinc, which one study has found to be essential in helping to regulate serum testosterone levels in men. You can add zinc to your diet by eating whole grains and shellfish, or through supplements.
  • Potassium aids in testosterone synthesis. Add potassium-rich food into your meals like bananas, beets, and spinach.
  • Get more exercise, which naturally increases testosterone.
  • Reduce the amount of sugar you consume.
  • Get more sleep.
  • Reduce the stress in your life, or learn stress management techniques.

There can be many reasons for a drop in your sex drive. Decreasing testosterone levels could be the source, but so could life stresses or relationship problems.

Testosterone supplements can boost sex drive for some, but ask your healthcare provider for testosterone testing to determine whether supplementation is the best option for you, as they have been linked to prostate cancer and cardiovascular issues.