Testosterone is the hormone responsible for developing and maintaining male sexual characteristics, leading to the development of features like a deep voice and body hair beginning in puberty. It helps to maintain muscle and prevent bone loss and is necessary for natural libido and sexual function in men. However, as we age, our testosterone levels naturally decline — testosterone levels can begin dropping as early as 35 years of age. This decline can lead to a reduction in libido, energy and strength, along with symptoms like erectile dysfunction and difficulty concentrating. Hormone replacement therapy can be an effective treatment for the symptoms of low testosterone. Testosterone can be supplemented via injection, but for patients seeking a less invasive option, topical testosterone cream offers a painless solution to get you back to feeling like your younger self.