Testosterone’s heart scare has eased, but its fertility catch has not

Key takeaways

• U.S. urologists define low testosterone as symptoms plus a level below 300 ng/dL on two early-morning blood tests taken on different days⁵.
• In a 2022 secret-shopper test, 6 of 7 online clinics offered testosterone to a 34-year-old man with a normal level who said he wanted children someday¹.
• The Endocrine Society says testosterone therapy suppresses sperm production and advises against it for men planning a pregnancy soon⁶.
• In February 2025, the FDA ordered heart-risk language taken out of testosterone’s boxed warning, its most serious alert, while requiring blood pressure warnings on every product⁹.
• For women, the only use with solid trial support is distressing low sexual desire after menopause, and the FDA approves testosterone products only for men⁹¹³.

In 2022, a doctor at Northwestern Medicine in Chicago went shopping for testosterone online. Dr. Justin Dubin played a 34-year-old man who felt tired and had little interest in sex. He also said he hoped to have children someday¹².

His total testosterone was a normal 675 ng/dL, well inside the lab’s range of 264 to 916¹.

Six of the seven online clinics he tested offered him testosterone anyway¹. Only one asked about his heart history or his plans for children. By the authors’ count, half of the clinics that offered treatment named a target of 1,000 ng/dL or more without discussing the risk to fertility¹.

That silence matters. The Endocrine Society, a major professional group of hormone specialists, says testosterone therapy suppresses sperm production⁶.

Regulators eased testosterone’s label in 2025 and asked for more changes in 2026⁹¹⁰. Here is what the hormone does, what “low” means by guideline, what the biggest safety trial found, and the catch many men never hear about.

Testosterone shapes energy, muscle, bone and sex drive

When testosterone runs truly low, the American Urological Association (AUA) lists the signs. They include less interest in sex, erection problems, low energy, fatigue, and loss of muscle or bone⁵.

The AUA calls these signs nonspecific, which is why a blood test has to back them up⁵.

Extra testosterone can push red blood cell counts too high, a condition called polycythemia. That’s why the AUA asks clinicians to check a blood count before treatment starts⁵.

Levels drift down with age. Normal aging lowers testosterone about 1% to 2% a year, according to a 2011 research letter in JAMA¹⁴. The Endocrine Society says the fall is gradual, differs from man to man, and runs faster in men with more body fat or chronic illness⁶.

There’s a twist. Much of your testosterone travels in the blood attached to a carrier protein called SHBG. That protein rises with age, so “free” testosterone, the unattached share, falls faster than the total⁶.

Women make testosterone too, in much smaller amounts. Their levels decline across the reproductive years and drop after the ovaries are removed¹³.

“Low T” takes symptoms plus two morning blood tests

Two professional groups set the U.S. rules, and they mostly agree.

The AUA’s 2018 guideline, reviewed and reconfirmed in 2024, treats a total testosterone below 300 ng/dL as a reasonable cutoff⁵. Ng/dL, or nanograms per deciliter, is the unit on most lab reports.

The test must be done twice, on separate days, both in the early morning⁵. A man also needs symptoms. A drop with age, on its own, doesn’t count as a deficiency⁵.

The Endocrine Society’s 2018 guideline asks for symptoms plus levels that are clearly and consistently low, confirmed with a repeat fasting test in the morning⁶. Its lower limit for healthy young men is 264 ng/dL. That figure comes from four large U.S. and European study groups, with labs matched to a CDC reference method⁶.

So a man at 280 ng/dL could look low by one standard and normal by the other.

The Endocrine Society also advises against routinely prescribing testosterone to every man 65 or older with a low number, and suggests deciding case by case⁶.

The AUA asks clinicians to measure one more hormone, luteinizing hormone (LH), the pituitary signal that tells the testes to work⁵.

Prescriptions soared, crashed, and are rising in the news again

Testosterone use climbed fast in the 2000s. A team led by Jacques Baillargeon tracked nearly 10 million men aged 30 and older with commercial insurance³.

In 2002, 0.52% of those men used testosterone. By 2013, 3.20% did³. By our math, that’s a jump from about 5 men in 1,000 to 32 in 1,000, roughly a sixfold rise.

Advertising helped. A 2017 study in JAMA, funded by NIH, tied TV ads to more testing and more new prescriptions in the 75 largest U.S. media markets⁴.

The link showed up before 2012, when most ads were unbranded “low T” campaigns about the condition rather than a named product⁴. AbbVie, the company that later led the funding of the biggest testosterone safety trial, paid for those early ads⁴⁸. Each month’s ad exposure had a tiny effect, about 0.05 extra new prescriptions per 10,000 men⁴.

Then came reports of heart attacks and strokes. Prescribing fell after the FDA’s January 2014 safety bulletin³. In March 2015, the FDA required label changes and urged caution about treating low testosterone caused by aging⁹.

By 2016, use had dropped to 1.67%, and new prescriptions had fallen 62% from their 2013 level³.

In July 2026, the Department of Defense announced yearly testosterone screening for active-duty service members 30 and older, Urology Times reported¹¹.

A big trial eased heart fears, and labels followed

In 2014, an FDA advisory committee recommended a large safety trial run by the industry⁹. The result was TRAVERSE, published in the New England Journal of Medicine in 2023⁷.

The trial enrolled 5,246 men aged 45 to 80 at 316 U.S. sites⁷⁸. All had symptoms, two fasting testosterone levels below 300 ng/dL, and either heart disease or a high risk of it⁷.

The men used a daily testosterone gel, adjusted to keep levels between 350 and 750 ng/dL, or a placebo gel⁸.

Over about 33 months, 182 men on testosterone and 190 on placebo had a heart attack, a stroke or a heart-related death⁷. That’s essentially a tie.

Atrial fibrillation (an irregular heartbeat), sudden kidney injury and blood clots in the lungs were more common on testosterone⁷. Our guide to longevity clinics lists the rates.

Read the fine print, too.

• Who paid. A group of testosterone makers led by AbbVie funded the trial⁷⁸.
• Time on treatment. Men used their assigned gel for an average of 21.7 months, well short of the 33-month follow-up⁷.
• What it tested. TRAVERSE was designed to check safety, not to prove benefit⁸.
• Who it applies to. Dr. A. Michael Lincoff of the Cleveland Clinic, the paper’s first author, warned against reading the results as permission to treat any man who feels tired or less interested in sex. The reassurance fits closely monitored men like those in the trial, he said⁸.

Labels changed in 2025, and more changes were requested in 2026

On February 28, 2025, the FDA told makers of every testosterone product to update their labels⁹. The changes:

• add the TRAVERSE results;
• remove boxed-warning language, the label’s most serious alert, about higher risk of heart and blood vessel problems;
• keep a “limitation of use” for low testosterone due to aging;
• add blood pressure warnings, because monitoring studies the FDA required in 2018 found that testosterone raised blood pressure across every type of product⁹.

On June 18, 2026, the Department of Health and Human Services announced that the FDA was asking for more changes¹⁰. The requests would drop the age-related limitation and narrow the prostate cancer restriction to cancer that has spread¹⁰. Screening and monitoring advice would stay¹⁰. The FDA noted that prostate cancer can take many years to develop, so some uncertainty remains¹⁰.

The American Urological Association described these as proposed changes, the start of a relabeling process¹⁰. We found no final labels as of October 2026, so ask your pharmacist which version your product carries.

The fertility catch many men never hear about

The Endocrine Society says testosterone therapy suppresses sperm production, and it recommends against the therapy for men planning a pregnancy in the near term⁶. Its guideline adds that men unsure about future children may want to bank sperm first⁶.

The AUA agrees. Men trying to conceive shouldn’t get testosterone, and men who may want children later should first hear about its long-term effect on sperm⁵. The CDC lists exposure to testosterone among the things that can harm male fertility¹⁵.

That’s what made the secret-shopper results worrying. None of the seven online clinics followed the guideline step of repeat morning testing¹. Consultations were run by nurse practitioners, physician assistants and, in some cases, a person with no medical license¹. Some offered a long menu of extras, from desiccated thyroid to peptides¹.

TCTMD’s report on the trial made a related point: many clinics don’t test testosterone before treatment or check it during⁸.

The Northwestern team suggests seeing a urologist, an endocrinologist or a primary care clinician². If children are anywhere in your future, say so before any prescription. Our companion article on fertility beliefs explains how often men are part of the picture.

For women, testosterone has one evidence-based use

In 2019, the Endocrine Society and 10 other medical groups backed a global consensus on testosterone for women, written by a task force of the International Menopause Society¹².

Its conclusion was narrow. The only evidence-based use is hypoactive sexual desire disorder, meaning low desire that causes distress, in women after menopause. Even then, it calls for a full look at physical, emotional and relationship factors first¹³. Co-author Susan Davis said the evidence doesn’t back testosterone for any other symptom or medical condition¹².

The statement drew on a review of 36 trials with 8,480 women. Testosterone added about one satisfying sexual event every four weeks¹³. It showed no benefit for mood, thinking, well-being, muscle or bone density¹³.

At doses meant to match younger women’s natural levels, the main side effects were acne and extra hair growth. There’s no safety data beyond two years¹³. The statement advises against custom-compounded testosterone¹³.

No blood level reliably marks which women have low desire. A baseline test mainly helps avoid overdosing¹³.

In the U.S., the FDA approves testosterone products only for men with low testosterone and a related medical condition⁹. Any prescription for a woman is off-label. Later articles on midlife sexual health go deeper.

What sleep, weight and daily habits can do

Lifestyle isn’t a side note here. The Endocrine Society describes “functional” low testosterone: levels pushed down by another condition and potentially reversible when that condition is treated⁶.

Its list includes severe obesity, some sleep disorders, heavy alcohol or marijuana use, opioid and steroid medicines, anabolic steroid use, poor nutrition and excessive exercise⁶. The guideline adds that managing obesity may bring health benefits beyond the hormone number⁶.

Sleep has the clearest experiment. In 2011, University of Chicago researchers had 10 healthy young men sleep about five hours a night for a week. Their daytime testosterone fell 10% to 15%, and they felt less vigorous¹⁴.

By our math, using the 1% to 2% yearly decline the authors cite, that’s 5 to 15 years of aging packed into a week. The study was tiny, and every man went through the same fixed sequence, so treat it as a strong hint, not proof¹⁴.

The Endocrine Society also recommends against using testosterone to improve blood sugar in men with type 2 diabetes⁶.

This approach fits natural-health values. If your level is low because of weight, sleep, alcohol or a medicine, the guideline’s own framework points first at that cause⁶. You don’t have to choose between habits and medicine. You can ask which one fits the cause.

Supplements sold to raise testosterone get their own article later in this series.

How strong is the evidence?

Claim	Rating	Why
Testosterone therapy suppresses sperm production	Strong evidence	Both U.S. guidelines and the CDC say so5615
Testosterone gel didn’t raise heart attacks, strokes or heart deaths in high-risk men with confirmed low levels	Strong evidence	TRAVERSE, 5,246 men; funded by makers78
Testosterone raises blood pressure	Strong evidence	FDA-required monitoring studies found it across products9
Testosterone gives a small sexual benefit to women with distressing low desire after menopause	Strong evidence	36 trials; about one extra satisfying event a month; no safety data past two years13
Testosterone for women’s mood, thinking, well-being or bones	Evidence says no, or unsafe	Trials found no benefit1213
Testosterone to control blood sugar in type 2 diabetes	Evidence says no, or unsafe	The Endocrine Society recommends against it6
Treating obesity, sleep problems or heavy drinking to lift functional low testosterone	Promising but early	A guideline category; we found no large trials to cite here6
Enough sleep to protect testosterone	Promising but early	One small, week-long study14

The testosterone question checklist, and when to get help

Stage	What to ask	Why it matters
Before testing	Could sleep, weight, alcohol, opioids or steroid medicines explain my symptoms?	These can lower testosterone in ways that may reverse6
Before testing	Can we book an early-morning blood draw?	Both guidelines rely on morning levels56
Reading the result	Was the low number repeated on a second morning?	One reading isn’t a diagnosis56
Reading the result	Which cutoff are we using, 300 or 264 ng/dL? Was LH checked?	The groups differ slightly, and the AUA asks for LH56
Risks to discuss	How will we track my blood pressure and blood count?	Labels warn about blood pressure; thick blood is a known risk59
Risks to discuss	What about my heart rhythm, kidneys, clot history and prostate?	TRAVERSE found more irregular heartbeat, kidney injury and lung clots; proposed labels keep prostate monitoring710
Risks to discuss	If I use a gel, how do I protect my partner and children?	The AUA asks clinicians to counsel about skin-to-skin transfer5
Fertility	Do I want a child in the next year, or ever?	Testosterone suppresses sperm; guidelines say avoid it if pregnancy is planned soon56
Follow-up	When do we recheck, and when do we stop if nothing improves?	The AUA suggests rechecks every 6 to 12 months, and a talk about stopping if symptoms don’t improve within 3 to 6 months5

When to see a clinician:

• Before starting anything. Get symptoms evaluated and testosterone tested twice in the morning, as the AUA advises⁵.
• If you use testosterone. Keep your scheduled checks of hormone levels and blood count, and watch your blood pressure⁵⁹.
• If you use testosterone and want a child. Tell your clinician now, and don’t stop or change a hormone on your own⁵⁶.

If you think a testosterone product harmed you, the FDA asks patients and clinicians to report it through MedWatch⁹.

Questions readers ask

The bottom line

Testosterone matters for energy, muscle, bone and sex drive, and it falls slowly with age. By guideline, “low T” means symptoms plus repeated low morning tests, not a single number or a birthday. For men with confirmed low levels and high heart risk, the biggest trial so far found no rise in heart attacks or strokes, and labels shifted to match, though blood pressure, heart rhythm and blood counts still need watching.

The catch is fertility. Prescribed testosterone can shut down sperm production, and some online clinics skip that conversation. If a child might be in your future, say so first. Ask whether sleep, weight, alcohol or a medicine is the real cause before you treat the number.

Keep exploring: is hormone therapy safe, hormone changes by age and testosterone booster supplements.

Related reading

• Fertility beliefs put to the test, starting with the fact that men play a part in about half of couples’ struggles
• How to sort longevity clinics that mix proven care with pricey experiments
• Real hormone problems have names and tests, which “balance your hormones” claims lack
• Ashwagandha lowers a stress hormone, and regulators are now splitting root from leaf
• Short sleep blunts insulin and stokes appetite, and adding sleep cut calories

Sources

1. Dubin JM, Jesse E, Fantus RJ, et al. “Guideline-Discordant Care Among Direct-to-Consumer Testosterone Therapy Platforms.” JAMA Internal Medicine, 2022;182(12):1321–1323. pubmed.ncbi.nlm.nih.gov
2. Northwestern Medicine. “Direct-to-Consumer Online Platforms Expand Access, but Often Fail to Convey Risks of Testosterone Therapy.” News release, January 5, 2023. news.feinberg.northwestern.edu
3. Baillargeon J, Kuo YF, Westra JR, Urban RJ, Goodwin JS. “Testosterone Prescribing in the United States, 2002-2016.” JAMA, 2018;320(2):200–202. pubmed.ncbi.nlm.nih.gov
4. Layton JB, Kim Y, Alexander GC, Emery SL. “Association Between Direct-to-Consumer Advertising and Testosterone Testing and Initiation in the United States, 2009-2013.” JAMA, 2017;317(11):1159–1166. jamanetwork.com
5. American Urological Association. “AUA Releases New Clinical Guideline for Diagnosis and Treatment of Testosterone Deficiency.” Press release, April 10, 2018; and “Evaluation and Management of Testosterone Deficiency” guideline page (published 2018, reviewed and validity confirmed 2024). auanet.org and auanet.org
6. Bhasin S, Brito JP, Cunningham GR, et al. “Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline.” Journal of Clinical Endocrinology & Metabolism, 2018 (Endocrine Society page and full-text copy hosted by the Alabama Board of Medical Examiners). endocrine.org and albme.gov
7. Lincoff AM, Bhasin S, Flevaris P, et al. “Cardiovascular Safety of Testosterone-Replacement Therapy.” New England Journal of Medicine, 2023;389(2):107–117 (abstract via Ovid). ovid.com
8. Cox CE. “Testosterone Doesn’t Cause CV Events in High-Risk Men With Hypogonadism.” TCTMD, June 16, 2023. tctmd.com
9. U.S. Food and Drug Administration. “FDA Issues Class-Wide Labeling Changes for Testosterone Products.” February 28, 2025. fda.gov
10. Urology Times. “HHS Requests Testosterone Therapy Label Updates, Citing New Safety Data.” June 19, 2026 (trade press); and American Urological Association. “HHS Announces Updates to Testosterone Replacement Therapy Labeling.” June 2026. urologytimes.com and auanet.org
11. Clarke H. “Testosterone Deficiency: FAQs From the AUA Guideline.” Urology Times, July 30, 2026 (trade press; used only for the Defense Department announcement). urologytimes.com
12. Endocrine Society. “Coalition Issues International Consensus on Testosterone Treatment for Women.” Press release, September 3, 2019. endocrine.org
13. Jang C, Boyle JA, Vincent A. “Global Consensus Statement on Testosterone Therapy for Women: An Australian Perspective.” Medical Journal of Australia, 2020;213(10):449–452. mja.com.au
14. Leproult R, Van Cauter E. “Effect of 1 Week of Sleep Restriction on Testosterone Levels in Young Healthy Men.” JAMA, 2011;305(21):2173–2174. pubmed.ncbi.nlm.nih.gov
15. Centers for Disease Control and Prevention. “Infertility: Frequently Asked Questions.” Published May 15, 2024, accessed October 2026. cdc.gov