Defense Secretary Pete Hegseth announced on Wednesday a new mandatory screening program to test all service members over the age of 30, including women, for testosterone deficiency annually.
Hormone treatment for troops with low testosterone will be voluntary.
“Our most decisive tactical advantage will always be the individual warfighter,” Mr. Hegseth said in a video from his Pentagon office. “We have a sacred duty to maintain that advantage.”
The goal, he said in a social media message accompanying the video, was a “High-T Department of War,” Mr. Hegseth’s preferred name for the Defense Department.
Mr. Hegseth’s focus on testosterone levels at a moment when U.S. forces are ramping up attacks in Iran is unorthodox. Defense secretaries typically focus on larger strategic questions, involving alliances, war and weapons production.
But Mr. Hegseth, a former Army National Guard officer and Iraq war veteran, has not shied away from getting involved in the minutiae of service members’ lives, such as mandating new grooming standards for troops who, because of skin conditions, had previously been permitted to grow beards.
“No more beardos,” he proclaimed.
Troops under 30 can volunteer to be screened, and anyone with low hormone levels will have the option to receive testosterone replacement therapy, or T.R.T. “It’s about restoring and optimizing your natural capability,” Mr. Hegseth said.
The aim, he said, is to better prepare service members for a modern battlefield that Mr. Hegseth described as “brutal and unrelenting.”
A clinically low level of testosterone in men can cause muscle loss, fatigue, obesity and sexual dysfunction, and is linked to other serious health problems, including diabetes, osteoporosis and depression.
Stress, poor sleep and head injuries, which are part of military life, can also cause lower hormone levels. Recent studies have identified a condition called “operator syndrome,” in which troops who have served long stretches in special operations units are more likely to report medical problems including decreased testosterone.
Use of the hormone comes with health risks, most notably to fertility, shutting down sperm production. It can increase the risk of blood clots, and often causes acne and hair loss.
Because of ongoing stigma, many service members avoid screenings for low testosterone or seek out hormone therapy from direct-to-consumer or illicit sources, Dr. Theodore Crisostomo-Wynne, a urologist at the Madigan Army Medical Center, said at a F.D.A. panel in December.
“There are service members who work their entire careers to get these special duty statuses that are very highly sought after,” Dr. Crisostomo-Wynne said. “And they worry that if they get seen for this disease and treated for it, that they may lose that status.”
While women also produce testosterone, men produce it at 10 to 20 times higher levels. There is no F.D.A.-approved testosterone treatment for women.
Though T.R.T. has legitimate medical use, the hormone has also been skyrocketing in popularity in the United States as a lifestyle drug to build muscle mass. Demand has grown from fewer than 1 million prescriptions in 2000 to nearly 12 million in 2025.
Low testosterone most often impacts men as they age. Of late, though, T.R.T. use is rising most rapidly among younger men, many of whom do not have clinically low testosterone levels. Popular influencers including Joe Rogan and Andrew Huberman have spoken publicly about their own use of T.R.T., as has Health Secretary Robert F. Kennedy Jr.
Mr. Hegseth, as defense secretary, has sought to cultivate an image as a manosphere-friendly leader. He regularly exercises with troops. He has overseen a ban on transgender service members and has questioned whether women are a detriment to ground combat units. The defense secretary has repeatedly blocked the promotions of women to general and admiral rank, even after they were selected by boards made up of senior officers.
He has also embraced the manosphere’s vaccine skepticism. Earlier this year, he ordered an end to mandatory annual flu vaccines, calling the policy an “absurd, overreaching” mandate. Two months later, after a flu outbreak at Air Force basic training that sickened hundreds and killed one trainee, the military reversed course and began requiring flu vaccines for all troops and trainees at initial entry units.
Mr. Hegseth’s order could have implications for the order that he and President Trump issued last year banning transgender troops from serving in the military. The ban, which is being challenged in federal courts, is partially rooted in the Pentagon’s insistence that transgender troops might not be able to access hormone therapy in a war zone.
“The Armed Forces must adhere to high mental and physical health standards to ensure our military can deploy, fight, and win, including in austere conditions and without the benefit of routine medical treatment or special provisions,” the Trump administration’s January 2025 ban states.
The Pentagon has not said why providing hormone therapy would be a problem for transgender troops, but not the rest of the force, though the executive order instituting the ban said that “radical gender ideology” was harmful to troop cohesion.
“Mr. Hegseth’s recommendation that male service members take testosterone makes crystal clear that the policy banning transgender troops for taking the same medication is pure bias,” said Shannon Minter, the legal director for the National Center for LGBTQ Rights. “This is a blatant double standard and underscores the irrationality of the ban.”
Mr. Hegseth’s move is in line with a recent push by Mr. Kennedy to expand access to T.R.T. among American men. Studies in several countries have shown that testosterone levels, which decrease slowly with age, are lower among younger generations of men than historical averages.
While many researchers have argued that the trend is being driven by rising obesity and increasingly sedentary lifestyles, Mr. Kennedy has called declining testosterone an “existential” threat to humanity.
