Testosterone replacement therapy can sound a little like the fountain of youth. Replace lost levels of the hormone, travel back in time to your younger years?
As guys age, their levels of testosterone tend to decline. And thats a big problem: Testosterone binds to proteins throughout your body and brain called androgen receptors, which help control and regulate a whole range of different bodily functions, explains Ronald Tamler, M.D., Ph.D., associate professor of medicine at the Icahn School of Medicine at Mount Sinai.
If theres not enough testosterone to go around, those androgen receptors all over your body and brain stay silent, leading to symptoms like low libido, weak erections and orgasms, inability to build muscle mass, low energy, or just feeling a little blue. A condition called hypogonadism low testosteronedevelops when your body cant produce enough of it.
Related: 8 Sneaky Signs Your Testosterone Is Too Low
Thats where testosterone replacement therapya treatment that raises your low testosterone levelscomes in. Testosterone can be supplemented in the form of an injection, a gel, a suction cup on your gums, and even a deodorant. It comes down to personal preference and what your insurance covers, says Dr. Tamler.
Now, testosterone therapy is just for guys whose levels are actually low, usually under 300 nanograms per deciliter (ng/dl) on a blood test. If youre in the normal range, T-therapy isnt on the tableand wouldnt do you good anyway, he says.
If you are prescribed testosterone therapy, youll likely start to see some changes, big and small, pleasant and not-so-pleasant. You may not see them all, and they may not all appear right away, but here are 9 benefits and drawbacks of testosterone therapy you should watch for.
When youre low on testosterone, you might notice your sex drive begin to dip. Androgen receptors are located in the parts of your brain that influence sexual desire, so if you dont have enough T to activate them, you may notice a drop in wanting to get it on, says Abraham Morgentaler, M.D., the director of Men's Health Boston and author of Why Men Fake It: The Truth About Men and Sexand Testosterone for Life.
When you replace your lost testosterone, that can activate those androgen receptors in the part of your brain that controls desire. In fact, regaining a healthy sex drive is one of the biggest benefits of testosterone replacement therapy, says Dr. Morgentaler.
In addition to upping libido, T-therapy can possibly make your erections more satisfying, too. You need to have testosterone to work on the receptors in the penis to help it trap blood to keep it [erect], says Dr. Tamler. Receptors help steer that process, and if you dont have enough T then the process is impaired.
This isnt the only piece of the puzzle, thougherections also rely on healthy nerves and blood flow. So that means that testosterone therapy by itself isnt a cure for erectile dysfunction itself.
Related: 5 Ways Happy Couples Deal When Their Sex Drives Diverge
"Muscles are extremely responsive to testosteroneone of the most reliable things we see [when someone starts testosterone replacement therapy] is an increase in muscle mass," says Dr. Morgentaler.
This is because androgen receptors are found in muscle tissue, so testosterone activates them to stimulate growth. Of course, to make the most of this benefit, youll need to be doing your part by strength training as well.
In addition to an increase in lean muscle mass, some men report fat loss as well. While testosterone doesnt directly incite fat loss itself, part of it may be thanks to the uptick in muscle massthe more muscle you have, the higher your basal metabolic rate (or BMR) will be, which means your body will burn more calories at rest. (Want to max out the process even more? Try The 21-Day Metashred from Men's Health, the at-home workout plan that will help you build lean muscle and burn fat at the same time.)
Jed Kaminetsky, M.D., a clinical assistant professor in the department of urology at NYU Langone Medical Center also notes that this may be partially because testosterone improves overall motivation to get up and sweat it out, so if you're motivated to put in the work again, you'll see results.
Related: 7 Reasons You're Not Building As Much Muscle As You Could
"It's very common for men to come in with low T and one of their primary symptoms is fatigue," says Dr. Morgentaler. "And when we treat them, a lot of men will say that their energy has improved." Many men also report an improvement in the "brain fog" that can come along with low testosterone, adds Dr. Tamler.
While researchers aren't exactly sure how exactly testosterone plays a role in energy yet, Dr. Morgentaler says one of the thoughts is that it has an effect on your mitochondria, which produce energy within cells. This case isnt closed on this yet, but the theory is that "testosterone turns them on so they're more productive in terms of creating the energy that the cells need."
Dr. Tamler also notes that it may be tied back to androgen receptors as well. "If they don't get sufficient input, that can cause fatigue," he says. So bringing testosterone levels back up can help reverse this.
Related: The 8 Best Foods to Keep You Energized All Day Long
Similar to its effects on energy, experts don't have a definitive answer to why testosterone impacts mood so deeplyafter all, "the brain is a complicated thing," says Dr. Tamlerbut they do see it as a potential life-changing benefit.
"In some ways, the impact on mood is one of the most profound benefits of T that we see," says Dr. Morgentaler. "Not everybody has that, but when we see it, it's remarkable. In my practice, patients will say, 'Oh, my mood's OK, maybe I just feel a little bit tired or blah.' And they come back and they say things like, 'I wake up in the morning and I'm optimistic about my day. I haven't felt that way in years.'"
In fact, a 2012 study published in The Aging Male found that after 12 months of testosterone therapy, the percentages of guys with moderately severe to severe depression symptoms decreased from 17 percent to 2 percent.
And more recent research also backs that up: "The largest randomized control trial for T was just completed a year ago, called the T Trials, and it showed that men who received T had a greater improvement in mood than men who received placebo," notes Dr. Morgentaler.
Related: 7 Surprising Symptoms Of Depression In Men That Prove It's Not All About Sadness
This is one of the most common side effects of testosterone replacement theory.
Normally, when your pituitary gland senses that there's not enough testosterone in the bloodstream, it sends down a hormone called luteinizing hormone (LH) to signal your testicles to start producing more testosterone, and a hormone called follicle stimulating hormone (FSH) to signal sperm production.
Related: Why Your Balls Might Feel Like a Bag Of Worms
When you take outside testosterone, the pituitary gland gets the memo that there's enough T in your bloodstream, so it stops sending these signals. This essentially puts the testicles to sleep (read: little or no sperm and testosterone production), says Dr. Kaminetsky.
"Most of the size of the testicle is dedicated to making sperm, so when you're making less sperm, the testicles get smaller," says Dr. Morgentaler. This also means it can hamper fertility, acting like birth control, so if you're planning on having kids, testosterone replacement therapy isn't an option.
6 Things Every Man Should Know About His Penis:
And production doesn't always go back to normal afterwards, either says Dr. Kaminetsky. A 2017 study in Fertility & Sterility found that increasing age and longer length of T-therapy was linked to less chances of normal sperm recovery. (Here are 7things you do every day that might be messing with your sperm.)
Some people notice a little swelling in their feet and ankles because testosterone can encourages your body to hold onto excess fluid, says Dr. Morgentaler.
This isn't a big deal for most people, he says, and its more common to see it if you're taking a non-daily treatment like an injection, where you're getting a higher dose of T in one sitting. You may notice a pound or two of difference on the scale, but it should melt away after a few days.
Related: Tom Brady Drinks 25 Glasses Of Water a Day. Should You Drink That Much, Too?
Going on testosterone replacement therapy may change your skin typefor better or for worse, says Dr. Morgentaler.
Like other hormones, testosterone can increase oil production, which isn't necessarily a bad thing. It's important for healthy skin, so you may actually end up with a better complexion. However, too much oily buildup can lead to breakouts.
Thankfully, this isn't that common, says Dr. Morgentaler, and it's typically seen in men who have a history of acne. (If you shudder at the reminder of your teenage skin, this might be a more likely side effect.)
Similar to the fluid retention, this is mainly seen with treatments like injections, when you're getting a higher dose all at once.
Related: 5 Reasons You Still Get Acne As a Grown-Ass Man
In all menwhether youre taking T or notsome testosterone is converted into the hormone estradiol, a form of estrogen. And in men who have more breast tissue by nature, the T they're taking that's naturally converted into estradiol could stimulate this breast tissue to grow.
This is called gynecomastia, says Dr. Morgentaler, and it's relatively uncommonhe says he doesn't even see one case a year.
If this does happen, though, your doctor will likely stop treatment for a month or two to allow your breast tissue to go back to normal, and then start you back up with T along with a drug that blocks the conversion of testosterone to estradiol.
Related: How to Get Rid Of Man Boobs
Testosterone replacement therapy has traditionally come along with serious warning labels that your risk for heart attack, stroke, and prostate cancer could rise, but this is still very controversialand recent evidence has begun to debunk some of these fears.
In the case of heart attacks and strokes, the concern is that testosterone thickens blood because it binds to androgen receptors that stimulate bone marrow to produce more red blood cells. Thicker blood is linked to a greater risk of heart attack and stroke.
But there isn't strong evidence to connect these cardiac events to testosterone itself, and some more recent studies actually suggest that normal testosterone levels might actually protect against these risks, says Dr. Morgentaler.
One mechanism at play here could be that reduced body fat is linked to overall better health, and testosterone replacement therapy can encourage this, says Dr. Morgentaler. More research is needed, he says, and to be safe your doctor will monitor your red blood cell count throughout your treatment.
As far as prostate cancer goes, this is fuzzy, too. Because there are androgen receptors in the prostate, testosterone can make it grow. So if you already have an enlarged prostate that makes it difficult to urinate, testosterone could exacerbate the issue, says Dr. Tamler.
Related: Should You Get the PSA Test to Screen For Prostate Cancer?
If you have existing prostate cancer, theoretically, testosterone could make it grow in the same way, says Dr. Kaminetsky. However, there isn't evidence to suggest that T actually causes prostate cancer.
Read more here:
Testosterone Therapy Effects: What to Expect After ...
