He added that most men who want to supplement their levels have no need for it, especially patients under 40. Most are after muscularity, he said.

“Young guys get this idea in their head, and they’re totally uninterested in what their physician has to say about it,” Dr. Welliver said. “Everybody wants to think they’re the biggest, toughest dude. The guys reading this stuff online come in with these weird treatments where they say their testosterone has to be at 5,000, when the normal is 400.”

The Supplements

There’s a long list of supplements that claim to boost T, all with little — or unknown — scientific backing. DHEA , a hormone naturally produced by the adrenal glands, can be taken as a supplement, though its ability to improve one’s sex life is unproven.

Another popular supplement is deer antler, a traditional Chinese medicine touted by athletes and Instagram fitness gurus for its T-enhancing powers, despite the lack of research to back that claim. Deer antler spray has been banned by the National Football League and Major League Baseball because it contains insulin-like growth factor 1, or IGF-1, which is considered a performance enhancing drug.

In 2013, seeking to lift heavier weights, Peter, then a 29-year-old technical recruiter from New York, began experimenting with supplements. He bought a 500 gram tub of API Health Deer Antler Manuka Honey, a mixture of honey native to New Zealand and deer antler extract. It was an impulse buy, he said, prompted by internet research and reports of deer antler’s curative powers by the N.F.L. star Ray Lewis.

Peter noticed no increased anabolic output and hasn’t used the supplement in years.

“ There are no studies that show any effectiveness of these supplements, and they’re certainly a cause for concern for safety and toxicity,” said Mark Peterson, who researches the relationship between testosterone deficiency and muscle strength at the University of Michigan. “If you’re taking an obscure supplement bought online and not even in a health store, you’re taking a chance.”