Welcome to Testosterone HQ—Men’s Health‘s guide to the exciting, complicated, and revolutionary world of testosterone. For everything you need to know about T, click here.
TESTOSTERONE IS CRUCIAL for building muscle and fueling your sex drive. It’s also essential for maintaining bone mass, producing red blood cells, and other bodily functions. Receptors for the hormone actually exist throughout your body, from your brain to your bones to your blood vessels.
So if your levels are low, also referred to as having low T, the health consequences could extend far beyond the gym and the bedroom, says UW Medicine endocrinologist Bradley Anawalt, M.D., who’s a spokesperson for the Endocrine Society.
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While most men see their testosterone drop a bit with age, you could experience low T in your 20s or 30s. “Testosterone deficiency is considered a medical condition and is different than an age-related decline in testosterone levels,” says Darshan Patel, M.D., assistant professor of urology at the University of California San Diego’s Men’s Health Center.
To diagnose low T, doctors find out what symptoms you’re experiencing (more on that in a minute). Then, you’ll need two blood tests (each on a different day), performed in the morning when testosterone is at its peak. The American Urological Association says that a total testosterone level of 300 nanograms per deciliter (ng/dL) or lower is a reasonable cutoff for suspected testosterone deficiency. Some experts suggest the cutoff could be as low as 264. Either way, the recommendation for testosterone replacement isn’t just based on that number; it’s based on whether you have symptoms, too.
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Low T affects people in different ways. It can manifest in physical, cognitive, and sexual ways, Dr. Patel explains. “Most men don’t experience them all, but rather a select few.”
The 13 symptoms that follow aren’t proof of low testosterone on their own, either. You need those blood tests, too. If low T is truly to blame for what you’re feeling, many of the health side effects of low testosterone can be reversed, or at least improved, with testosterone therapy.
1. Low testosterone symptom: Your libido drops.
Perhaps the most common effect of low T is low libido, says urologist Philip Werthman, M.D., director of the Center for Male Reproductive Medicine and Vasectomy Reversal in Los Angeles.
Nearly every patient who comes to his office with known or suspected low T complains of a lack of sexual appetite. Besides wanting less sex, men with low T may also masturbate less and report fewer fantasies and erotic dreams.
Brain areas involved with sexual desire, including the amygdala, are packed with testosterone receptors, says S. Adam Ramin, M.D., urologic surgeon and medical director of Urology Cancer Specialists in Los Angeles. The hormone fits inside them like a lock inside a key, lighting them up to arouse you. Without it, you’re missing a critical step in the turn-on process.
2. Low Testosterone Symptom: You might struggle to get an erection.
“Testosterone is necessary for the development and maintenance of erectile function in men,” says Brian Black, D.O., osteopathic board-certified physician in family medicine.
Testosterone helps you achieve and maintain an erection by signaling the brain to trigger the chemical reaction that helps you get and stay hard. Low T might make it difficult to get an erection, or you might have spontaneous erections.
But the relationship between testosterone and erectile function is complicated. Some men don’t have any trouble getting an erection when their testosterone is low. In addition, your quality of orgasm or ability to achieve orgasm can suffer.
Erectile dysfunction can also be a sign of many chronic conditions, like heart disease, obesity, and diabetes.
3. Low testosterone symptom: Your muscles shrink.
Ample testosterone puts your body in an anabolic, or muscle-building, state by helping your body produce and assemble proteins that form the building blocks of lean mass. When your testosterone levels drop, your body turns catabolic instead, breaking down muscle tissue instead of building it up, Dr. Werthman says.
At first, you might notice that it’s tougher to push as much weight at the gym or build muscle, he notes. And after a few weeks of low T, you can expect to lose muscle mass, Dr. Anawalt says. In one Japanese study, men with low free testosterone levels—a measure of the amount of hormone that’s not bound to receptors—had double to triple the risk of muscle loss with aging as those with normal levels.
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4. Low testosterone symptom: Your penis may get smaller.
Without a steady flow of testosterone, the tissues in your penis, scrotum, and testicles can atrophy, or shrivel, says Dr. Ramin. As a result, your penis might lose length and girth. You may notice your balls shrink, too—they often shrivel to half the size and turn squishy instead of firm, he says.
Though testosterone replacement therapy won’t bring back your testicular volume, when it comes to your penis, the treatment “has a good chance of restoring its glory,” Dr. Ramin says.
5. Low testosterone symptom: Your belly grows.
Even as you lose size where it counts, you gain it where it hurts, Dr. Anawalt says. A while back, Australian researchers saw men with prostate cancer gain 14 percent more body fat and 22 percent more visceral fat than they had at the start of the study after one year of androgen deprivation therapy, a treatment which turns off testosterone’s effects.
Visceral fat is the deep abdominal fat that forms around your organs and increases your risk for diabetes and heart disease.
The link between obesity and low testosterone is a “vicious cycle,” says William Nall, D.O., owner of Village Osteopath in Noblesville, Indiana, and an osteopathic board-certified physician in neuromusculoskeletal medicine.
“Low testosterone lowers your motivation to go out and do things, which might cause you to put on weight,” Dr. Nall says. Excess body fat can, through a complex interaction of hormones and enzymes lower testosterone levels.
6. Low testosterone symptom: You develop brain fog.
Trouble with thinking and memory often occurs in men with low T, Dr. Werthman says. In addition to the amygdala, areas of the brain important for memory and attention—such as the cerebrum—also have testosterone receptors. When there’s not enough of the hormone available to those receptors, your brain cells may not be able to function as well.
7. Low testosterone symptom: Your mood tanks.
Some of the side effects of low testosterone—such as sexual dysfunction and weight gain—can bring on the blues. But there’s also evidence of a more direct effect of low testosterone on mood, and empty testosterone receptors in brain areas linked to mood are likely responsible for your depressed state, Dr. Ramin says.
What’s more, mood disorders like depression or anxiety can kick off a troublesome cycle, he notes—depression can suppress your testicles’ ability to produce testosterone, worsening the problem.
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8. Low testosterone symptom: Your bones weaken.
Bone is actually living tissue, constantly broken down and rebuilt, Dr. Ramin says. When testosterone levels fall, your bone breaks down faster than your body can build it back up.
As a result, you’re at a higher risk of low bone density, osteoporosis, and fractures, Dr. Anawalt says.
Bone density changes as you get older, and combined with low T, it can make you have a stooped, or bent-over, appearance, explains Dr. Nall. This, combined with the loss of muscle mass might make you feel achy.
The best say to build bone density is with weight-bearing exercise. Combining TRT with weight lifting is very useful for getting your bone density where it should be.
9. Low Testosterone Symptom: You might lose your hair.
As you get older, you’ll likely see your hair thin and may even start to go bald. If you have low T, you might lose body and facial hair, too, Dr. Nall says. You may also notice that your beard isn’t growing as quickly and you don’t have to shave as much. Testosterone is a crucial hormone for the growth of facial and body hair, so when it’s low, it interferes with the hair-growing process.
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10. Low Testosterone Symptom: You could develop anemia.
It’s less common, but low T could cause you to develop anemia. A 2017 study revealed that when older men who were anemic received testosterone therapy, they saw an increase in their levels of hemoglobin (the protein in red blood cells that carries oxygen throughout the body).
You might not know you’re anemic unless you have blood work done at your doctor’s office, though. Some signs to watch out for, according to the Cleveland Clinic, include shortness of breath, dizziness, irregular heartbeat, a whooshing sound in your ear, headaches, and chest pain.
11. Low Testosterone Symptom: Your energy levels drop.
Low T can cause fatigue and decreased energy, Dr. Black says. You might not feel like doing the things you usually do, or your usual activities tire you out more than usual.
“It’s not a psychological thing or situational; it’s just that you don’t feel like going out and doing things anymore,” Dr. Nall says. You might also notice that you don’t recover as quickly from physical activity as you used to or need to take naps to get through the day.
A 2019 study found that when men received testosterone therapy, 52.4 percent said their energy levels improved.
12. Low Testosterone Symptom: You develop gynecomastia.
When testosterone levels are low and estrogen levels increase, gynecomastia, or developing male breasts, is possible, Dr. Patel says. This more commonly happens in men with obesity; body fat helps is associated with an increase in the enzyme aromatase, which encourages the conversion of testosterone to estrogen in the body. The rise in estrogen can promote gynecomastia. Along with noticing swollen breast tissue, you could experience pain, tenderness, and sensitive nipples, especially when they rub against your clothing, according to the Mayo Clinic.
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13. Low testosterone symptom: Your heart might be at risk.
The effect of testosterone levels on the risk of heart problems has stoked controversy among experts, Dr. Anawalt says. On one side, low levels of testosterone may be linked to heart problems. In fact, one study from the U.K. found men with low T had a greater risk of dying from heart disease than men with normal levels.
This may be because testosterone can help open up blood vessels to the heart, allowing blood to flow more freely.
But on the flip side, some studies have suggested that testosterone therapy—especially in older men or those with existing heart conditions—might increase the risk of heart attack or stroke. Experts think it may thicken the blood, making a clot more likely.
Yet a big 2023 study in the New England Journal of Medicine found that men who took testosterone replacement therapy didn’t have more cardiovascular events than men who took a placebo, although they did have higher rates of pulmonary embolism, acute kidney injury, and atrial fibrillation.
When to Talk to Your Doctor About Low T
If you’re experiencing any of these symptoms, talk to your doctor about getting your testosterone levels checked. You could be prescribed testosterone therapy if you have low T.
“It is generally not necessary for people to worry about their exact testosterone number unless they are experiencing symptoms of concern,” Dr. Black says.
Your doctor may test your testosterone levels after you first start therapy or change dosages to make sure your levels aren’t surging too high, Dr. Anawalt says.
