Testosterone & Men's Hormones

What does testosterone actually do in men?

Testosterone builds and maintains muscle mass and bone density, drives red blood cell production, influences where the body stores fat, and is central to libido — desire, specifically. It is made mostly in the testes on instruction from the brain, and part of it converts into estradiol, which men genuinely need for bone, mood and libido. Testosterone is not the opposite of estrogen in men; the two work together.

Testosterone in midlife, the long version

What does testosterone not do?

Testosterone is not a general vitality hormone, not a treatment for growing older, not an antidepressant, and not a reliable treatment for erectile dysfunction. Erections depend mainly on blood vessels and nerves, which is a different question covered in the sexual health answers. In a man whose level is genuinely normal, adding testosterone is a performance-enhancing drug rather than a treatment. Most of what the category advertises belongs on this list rather than on the list of things testosterone actually does.

Testosterone in midlife, the long version

What are the symptoms of low testosterone in men?

The symptoms usually attributed to low testosterone are fatigue, low mood, poor concentration, weight gain, poor recovery from training, reduced libido, and loss of muscle and strength. The more specific signs — shrinking testes, loss of body hair, breast tenderness, hot flashes — are far less common but much more informative when they are present. A symptom picture on its own is not a diagnosis of low testosterone, because the common symptoms are shared with a long list of other conditions.

Low testosterone: what it looks like

Why is the low testosterone symptom list so unreliable?

Every common symptom of low testosterone — fatigue, low mood, poor concentration, weight gain, low libido — belongs to at least five other conditions, several of which are more common and more treatable. The link between how a man feels and where his testosterone number sits is also weaker than people expect: men near the bottom of the range often feel entirely well, and men in the comfortable middle often feel terrible. That is why a credible diagnosis needs both halves — a consistent symptom picture and a genuinely low measurement, repeated. A symptom list that fits everyone identifies no one.

Why the diagnosis is harder than the ads suggest

How much does testosterone decline with age?

Testosterone falls on average by a small percentage a year from somewhere in a man's thirties, and most men remain inside the laboratory reference interval into their seventies. There is no male equivalent of menopause in the population data — no cliff edge at fifty, whatever the advertising implies. A man whose level has fallen a long way usually has a reason beyond age, such as weight, sleep apnea, alcohol, a medication or chronic illness, and finding that reason is more useful than treating the number.

Testosterone Levels by Age

Why does testosterone have to be tested in the morning?

Testosterone follows a daily rhythm that peaks in the early hours after waking and drifts down through the day, and the reference ranges laboratories report against were built from early-morning samples. An afternoon draw compared against a morning range is one of the most common ways a healthy man gets told he is deficient. Fasting matters for the same reason: eating lowers testosterone acutely.

Blood tests before hormone therapy

Why does a low testosterone result need to be repeated?

A single low testosterone result means very little, because day-to-day variation within the same man is wide — a bad night's sleep, a heavy training block, an infection, a course of steroids or a week of heavy drinking will all push a reading down. Two separate early-morning samples are the minimum before anyone should be having a conversation about treatment. Repeating the test costs a couple of weeks and regularly changes the answer.

How testosterone is properly measured

What is the difference between total and free testosterone?

Total testosterone measures everything circulating, most of which is bound and unavailable to your tissues: a large share is held tightly by sex hormone binding globulin, more is bound loosely to albumin, and only a small free fraction is doing anything. Free testosterone is usually calculated from total testosterone, SHBG and albumin rather than measured directly, because direct free testosterone immunoassays are unreliable enough that most guidelines discourage them. A total testosterone read without SHBG can mislead in either direction.

What a baseline panel covers

Why does SHBG change how a testosterone result is read?

SHBG — sex hormone binding globulin — carries most of the testosterone in your blood, so the same total testosterone means different things at different SHBG levels. SHBG rises with age, an overactive thyroid, liver disease and some medications, and falls with obesity, insulin resistance and an underactive thyroid. A respectable total testosterone sitting on a high SHBG can conceal a genuinely low free level, and a modest total on a low SHBG can be entirely adequate.

What SHBG Is, and Why It Changes Your Result

What is the difference between primary and secondary low testosterone?

Primary means the testes are the problem: the brain is asking loudly, LH and FSH come back high, and output is still low — from causes such as prior mumps orchitis, testicular injury or surgery, chemotherapy, or a genetic condition, and it is usually permanent. Secondary means the instruction is the problem: testosterone is low while LH and FSH are low or unremarkable, most often from obesity, obstructive sleep apnea, opioids, glucocorticoids, heavy alcohol use, chronic illness, a severe training and energy deficit, or past anabolic steroid use. The distinction changes the treatment, because secondary causes are often reversible and the medications that stimulate your own production only work if the testes are still able to respond.

Secondary hypogonadism, explained

Is it better to replace testosterone or stimulate my own production?

Neither is simply better. Replacement supplies testosterone from outside and reliably raises the level, at the cost of shutting your own production down — LH and FSH fall, the testes usually shrink, and sperm production is suppressed. Stimulation with enclomiphene or clomiphene works on the feedback loop instead, so your own testes make more and testicular function stays in play, but it does less, less predictably, and only where the low testosterone is secondary. Replacement is more certain and more suppressive; stimulation preserves the axis and suits a narrower group of men.

Replacing it, or stimulating it

How does enclomiphene work?

Enclomiphene is a selective estrogen receptor modulator that blocks estrogen feedback at the hypothalamus and pituitary, so the brain reads the situation as lower than it is and signals harder. LH and FSH rise and the testes respond by producing more of your own testosterone — the key difference from replacement, where the hormone arrives from outside. Enclomiphene only works where the testes are still capable of responding, which makes it an option in secondary low testosterone and not in primary.

Enclomiphene ODT

What is the difference between enclomiphene and clomiphene?

Clomiphene is a mixture of two isomers and enclomiphene is one of them, isolated. The other isomer lingers in the body for a long time and carries much of the side-effect burden, which is the argument for using the isolated form. Both act the same way — blocking estrogen feedback at the brain so LH and FSH rise — and both are used off-label in men.

Enclomiphene and Clomiphene: What Separates Them

Is enclomiphene FDA-approved?

No — enclomiphene is not FDA-approved: it was developed as Androxal, received a Complete Response Letter in 2015, and the additional trials the FDA asked for were never completed. In 2022 the FDA's Pharmacy Compounding Advisory Committee voted against adding enclomiphene citrate to the 503A Bulks List, and compounded enclomiphene remains available largely because it is a component of FDA-approved clomiphene. Compounded medications are not FDA-approved, are not reviewed by the FDA for safety or effectiveness, and are not equivalent to or interchangeable with any branded product.

Enclomiphene and Clomid compared

Can I switch from testosterone therapy to enclomiphene?

Switching from testosterone therapy to enclomiphene is sometimes possible, but it is not a straight swap. Coming off testosterone replacement leaves the axis suppressed and your own production has to restart, which takes months, is not guaranteed to return to where it began, and can be an uncomfortable stretch in between. Enclomiphene can only pick up the work if the underlying problem was secondary and the testes are able to respond, so this is a decision made with labs and a clinician rather than a preference.

Testosterone Therapy or Enclomiphene

Does testosterone therapy cause infertility?

Testosterone replacement suppresses sperm production, in many men to the point of infertility, and that is how the drug works rather than a rare side effect. Hormone arriving from outside switches off the pituitary signals that drive the testes, and the testosterone concentration inside the testes — which sperm production depends on — falls much further than the blood level suggests. Any man who might want children should settle this before starting, not after.

Testosterone Therapy and Fertility

Is testosterone therapy a form of birth control?

No — testosterone therapy is not a form of birth control, and it must never be used as contraception. Suppression of sperm production is common but not universal, not complete in every man, and not predictable in its timing. Men have conceived while on testosterone therapy. Contraception should continue if a pregnancy would be unwelcome.

Male fertility testing

Will my fertility come back if I stop testosterone therapy?

Fertility usually comes back after you stop testosterone therapy, but not always, and not quickly. Sperm production commonly recovers after testosterone therapy stops, over months rather than weeks, and the odds get worse with longer use and older age. Recovery is not guaranteed, which is exactly why the fertility conversation belongs before treatment starts — and where fertility matters, enclomiphene works with the axis rather than suppressing it.

Enclomiphene and fertility

Should I have a semen analysis before starting testosterone therapy?

Yes — have a semen analysis before starting testosterone therapy if children are a possibility, or you are not certain they are not. A baseline semen analysis before testosterone therapy tells you what you are starting from, and once replacement has suppressed sperm production a later test cannot separate the treatment from whatever was already there. It is inexpensive, non-invasive, and collected at home.

Male fertility testing

What does testosterone therapy actually improve?

In men with confirmed low testosterone, the most consistent benefit of testosterone therapy is sexual desire, which improves modestly and fairly reliably. Lean mass rises and fat mass falls, although whether that converts into strength or function you would notice is much less clear and does not happen without training. Bone density improves, and anemia improves in men who were anemic; cognition does not improve. None of this applies to men whose levels are normal.

What the evidence supports

Does testosterone therapy improve energy and mood?

Testosterone therapy does less for energy and mood than most men expect. The Testosterone Trials, the best-designed set of studies in older men, found a small improvement in mood and depressive symptoms and no meaningful effect on vitality — which is the thing most men come in asking for. Some men report a clear change, but the average effect across a trial population is small, and symptoms improve in placebo arms at rates that should make everyone modest. If flat energy is the main complaint, sleep, iron, thyroid and mood are worth excluding first.

Still Tired on Testosterone Therapy

Is testosterone therapy safe for the heart?

The best available evidence does not show an excess of major adverse cardiac events with testosterone therapy in men who have confirmed low testosterone, which is a real change after a decade of conflicting findings. It is not a clean bill of health: the same large trial that provided that reassurance found more atrial fibrillation, more pulmonary embolism and more acute kidney injury in the treated group. Cardiovascular history belongs in the decision and should be discussed with the clinician prescribing rather than assumed either way.

Cardiovascular safety in context

What did the TRAVERSE trial show?

The TRAVERSE trial, reported in 2023, showed no excess of major adverse cardiac events in men treated with testosterone gel compared with placebo. It randomized more than five thousand middle-aged and older men who had low testosterone plus existing cardiovascular disease or risk factors to testosterone gel or placebo. That is the strongest cardiovascular safety evidence testosterone therapy has, and it is genuine reassurance. TRAVERSE also found more atrial fibrillation, more pulmonary embolism and more acute kidney injury with testosterone, and it says nothing about men outside that population or about decades of use.

Why is hematocrit checked on testosterone therapy?

Testosterone stimulates red blood cell production and in some men it overshoots, and a rising hematocrit thickens the blood — it is the single most common reason testosterone therapy gets reduced or paused. It is measured before starting and at intervals afterwards, which is a large part of why this is a monitored treatment rather than a prescription you collect and forget. Sleep apnea, smoking and altitude push hematocrit the same way, so a high result is worth explaining rather than simply reacting to.

Hematocrit: Why It Gets Watched

Why is PSA checked before and during testosterone therapy?

PSA is measured before testosterone therapy so there is a baseline, then rechecked in the first year and periodically afterwards, because the clinical concern is that testosterone could accelerate a prostate cancer that is already present. A rise beyond what is expected prompts a urology referral rather than an adjustment to the treatment. Prostate risk — age, family history, urinary symptoms — belongs in the conversation before anything is prescribed.

How men's hormone therapy is run here

Does testosterone therapy cause prostate cancer?

The long-held belief that testosterone therapy causes prostate cancer has not held up in the evidence, but the question is not considered closed, and testosterone therapy is not given to a man with active prostate cancer. The residual concern is acceleration of a cancer already present, which is why a baseline PSA and a prostate risk discussion come before treatment and monitoring continues during it. Anyone with a personal or family history of prostate cancer should raise it explicitly with the clinician assessing them.

Who Should Not Take Testosterone Therapy

Should I take an aromatase inhibitor to control estrogen on testosterone therapy?

An aromatase inhibitor is usually not the first move to control estrogen on testosterone therapy. Testosterone converts into estradiol, so raising one raises the other, and men need estradiol — over-suppressing it causes bone loss, joint pain and the loss of the libido the treatment was meant to help. When estradiol runs high enough to produce breast tenderness, fluid retention or mood changes, the first things to look at are body fat, the testosterone level itself and the formulation, rather than adding another medication.

High Estradiol in Men: Why It Shows Up

What happens when you stop testosterone therapy?

Stopping testosterone therapy leaves you with whatever your own production has recovered, which at first is very little, because the axis has been suppressed throughout treatment. Most men feel worse than they did before they started for a stretch — fatigue, low mood, low libido — while LH and FSH restart and the testes resume work, which takes months rather than weeks. Recovery is usual but not guaranteed, and it is slower after longer use and at older ages, so stopping is worth planning with a clinician rather than doing abruptly.

What Happens When You Stop

Do I have to stay on testosterone therapy forever?

You do not necessarily have to stay on testosterone therapy forever, but planning for the long term is the honest default. Testosterone replacement treats a level rather than curing a cause, so in primary low testosterone it is generally indefinite; where the cause was secondary and reversible — weight, sleep apnea, alcohol, opioids, an energy deficit — treating that cause can make ongoing therapy unnecessary. There should also be a defined point at which everyone asks honestly whether the treatment changed anything, and if nothing has after a fair trial, the right answer is to stop rather than keep adjusting.

Do You Have to Stay on It Forever?

Is oral testosterone as effective as injections?

Modern oral testosterone can raise levels into the intended range, so the real differences from injections are practical rather than one working and the other not. Injections are taken far less often and are cheaper, and they produce peaks and troughs between administrations; the oral route has to be taken consistently with food containing fat, produces a different daily pattern, and calls for blood pressure to be watched because increases have been reported with it. Both suppress your own production and sperm production in the same way — the route does not change that.

Oral Testosterone or Injection

Can sleep apnea cause low testosterone?

Yes — sleep apnea can cause low testosterone: obstructive sleep apnea fragments sleep and blunts the overnight rise in testosterone. It also produces exactly the fatigue, irritability and low libido that get attributed to hormones — so it is both a cause of low testosterone and a convincing mimic of it. It is common in men over forty-five who have gained weight, it is frequently undiagnosed, and treating it can raise testosterone with no hormone at all. Testosterone therapy can also worsen sleep apnea, so anyone with symptoms should be assessed before starting.

Testosterone Therapy and Sleep Apnea

Does losing weight raise testosterone?

Yes — losing weight often raises testosterone, because fat tissue converts testosterone into estradiol, which strengthens the feedback signal telling the brain to stop asking. Excess weight — visceral fat in particular — lowers testosterone through a real mechanism rather than an association. Meaningful weight loss raises testosterone more dependably than most interventions aimed at the hormone directly, and unlike replacement it does not suppress your own production.

Weight loss and testosterone

Does alcohol lower testosterone?

Yes, and the amount required is lower than most men assume. Alcohol suppresses the axis at both ends — it interferes with the signal from the brain and with production in the testes — and sustained drinking also wrecks sleep, raises body fat and worsens mood, each of which lowers testosterone independently. A few weeks of genuinely reduced intake before a repeat test is one of the cheapest things a man can do before committing to treatment.

Low testosterone: what else produces it

Could depression or a thyroid problem explain my symptoms instead of low testosterone?

Both can, and both are more treatable than a borderline testosterone level. Depression shares almost the entire symptom list — fatigue, low mood, poor concentration, low libido, disturbed sleep — and is treated completely differently. Thyroid disease produces the same fatigue and weight change and also moves SHBG, which distorts the testosterone result itself, which is why thyroid function belongs on the same panel rather than in a later round of testing.

Midlife or Thyroid?

Who should not take testosterone therapy?

Testosterone therapy is not appropriate for men with active prostate or breast cancer, and men who are trying to conceive or expect to want children soon should look at alternatives, because replacement suppresses sperm production. Caution or deferral applies with untreated obstructive sleep apnea, a raised hematocrit, uncontrolled heart failure, a recent cardiovascular event, a history of blood clots, significant untreated urinary symptoms and poorly controlled blood pressure. Eligibility is a clinical decision made after labs and a full history, and disclosing every medication and condition is what makes it a safe one.

Who Should Not Take Testosterone Therapy

Is "male menopause" a real condition?

"Male menopause" is not a real condition, and the borrowed term is the problem. Menopause is a discrete event that ends ovarian function in essentially every woman within a predictable window; the decline in male testosterone is gradual, partial, varies enormously between men, and in plenty of men is barely detectable into old age. Andropause carries the same implication of a universal deficiency that the population data do not support. A man whose testosterone has genuinely fallen a long way usually has a specific cause worth finding rather than an age worth accepting.

Low testosterone or just aging?

My testosterone is normal for my age but low compared with a young man. Does that count?

A testosterone level that is normal for your age can still count as low, because most clinical guidance applies a single threshold to adult men rather than an age-adjusted one. The reasoning is that symptoms do not become harmless because other men your age share your level. Age-adjusted ranges exist and some laboratories report them, but reading a result against your contemporaries can normalize a level that is genuinely causing trouble, and reading it against a young man can manufacture a deficiency that is not there. This is a question for the clinician reading the result alongside your symptoms, SHBG and the pituitary hormones, not one a reference interval settles on its own.

Low testosterone or just aging?

If my low testosterone is just aging, is there anything worth doing?

Yes — even if low testosterone is just aging, there is plenty worth doing, and most of what works is not hormonal. Resistance training with enough protein rebuilds the muscle and strength men usually mean when they say they feel older, and treating disturbed breathing in sleep, drinking less, losing excess weight, addressing mood and reviewing a medication list all move the same symptoms. In a man whose level is not actually low, those change how he feels more reliably than a prescription does — and several of them raise testosterone as a side effect rather than suppressing his own production.

Low testosterone or just aging?

My testosterone is normal but I have every symptom of low testosterone. Why?

A normal total testosterone alongside a full symptom picture usually means one of two things. Either the total is not telling the whole story — a high SHBG binds more of it and leaves less free testosterone available to tissue, which is why SHBG and a calculated free testosterone belong on the same panel — or the symptoms are being produced by something else entirely, such as obstructive sleep apnea, thyroid disease, anemia, depression or a medication. Both are worked through with a clinician, and ordering more hormones is not always the next step.

Secondary hypogonadism, explained

Can I just try testosterone for a few months and see if it helps?

Trying testosterone for a few months to see if it helps is a conversation some clinicians will have, but it is not the neutral experiment it sounds like. Therapy suppresses your own production and sperm production from the early weeks, recovery after stopping takes months and is not guaranteed, and an improvement in one person is very hard to separate from what happens in the placebo arms of these trials. If a trial is undertaken it needs a defined end point agreed at the start, and an honest answer at that point — including the answer that nothing changed.

When your level is borderline

Can an at-home finger-prick test diagnose low testosterone?

An at-home finger-prick test can flag a testosterone result worth following up, but it cannot diagnose low testosterone. Collection timing is harder to control at home, and the method is usually an immunoassay, which performs least well in exactly the borderline range where the answer matters most. A diagnosis needs two early-morning samples from the same laboratory, read alongside SHBG and the pituitary hormones and a history taken properly.

At-home blood tests versus a lab draw

My two testosterone results came back different. Which one is right?

When two testosterone results come back different, possibly neither is right on its own. Genuine day-to-day variation within the same man is wide, and draw time, fasting state and differences between laboratory assays all move the number, so two results that disagree are the expected outcome rather than a laboratory error. Use one laboratory, read against that laboratory's interval, and let a clinician weigh the pair against the symptom picture — picking the result you prefer is how men end up treated for a number that was never reproducible.

Getting the test right

Can secondary low testosterone be reversed without medication?

Secondary low testosterone can sometimes be reversed without medication, and it is worth looking for that before anything is prescribed. Secondary low testosterone means the signal from the brain is the problem, and the common reasons that signal is suppressed — excess weight, untreated obstructive sleep apnea, opioids, glucocorticoids, heavy alcohol use, a severe training and energy deficit — are things that can be changed. Removing the cause can restore your own production, which no form of replacement does. Where the cause is a prescribed medication, that change is made with the prescriber rather than by stopping it yourself.

Secondary hypogonadism, explained

When does low testosterone need a pituitary scan?

Low testosterone points at the pituitary when testosterone is very low while LH and FSH are low or unremarkable, when prolactin is raised, or when there are symptoms suggesting a mass — new headaches, a change in vision, or loss of other pituitary hormones. That combination prompts imaging and an endocrinology referral rather than a prescription, and it is not something a telehealth service manages. It is uncommon, which is precisely why it gets missed when a low result is treated without the pituitary hormones being measured alongside it.

Secondary hypogonadism, explained

Do opioids lower testosterone?

Opioids lower testosterone substantially and commonly, by suppressing the signal from the brain to the testes — so testosterone falls with LH and FSH low or unremarkable beside it. The effect relates to how much and for how long, and it applies to long-term prescribed pain treatment as much as to anything else, which makes it one of the most frequently overlooked explanations for a low result in a man over forty-five. Never stop or reduce a prescribed opioid to test the theory; raise it with the prescriber, who can weigh the pain treatment and the hormone question together.

Medications that lower testosterone

I used anabolic steroids years ago. Could that still be affecting my testosterone?

Yes — anabolic steroids used years ago can still be affecting your testosterone, because any androgen taken from outside shuts down your own production. Recovery after stopping takes months, is not guaranteed, and is less likely after longer or heavier use — so a course taken years ago can still be the explanation for a low result today. It is one of the more common causes of low testosterone in midlife and one of the most commonly left off an intake form. Say so: it changes the diagnosis, the likelihood that your own production can be restarted, and what treatment is reasonable.

Medications that lower testosterone

Does finasteride lower testosterone?

Finasteride does not lower testosterone. It blocks the conversion of testosterone into DHT, and total testosterone typically stays where it was or rises slightly. Sexual side effects on finasteride are recognized and should be taken seriously, but they are not a testosterone deficiency and testosterone is not the treatment for them — that conversation belongs with whoever prescribed the finasteride, and the sexual health answers cover what is and is not known about them.

Medications that lower testosterone

Do antidepressants cause low testosterone?

Antidepressants generally do not lower testosterone. SSRIs and SNRIs commonly reduce desire, delay orgasm and impair erections, but they do it through serotonin rather than through the hormone axis, which is why men taking them so often have unremarkable hormone results alongside entirely real symptoms. Treating that with testosterone is treating the wrong system. The useful conversation is with the prescriber about the specific drug, since switching agents is frequently possible — and stopping an antidepressant abruptly on your own carries its own risks.

Medications that lower testosterone

Does DHEA raise testosterone in men?

DHEA raises testosterone slightly or not at all in men across most trials, although it reliably raises DHEA-S, the marker it is judged by. It is a more meaningful androgen source in women than in men, whose testes already produce far more testosterone than the adrenal route contributes. Where DHEA is used in a man it is to restore a low adrenal precursor rather than as a testosterone treatment, and it is worth telling a clinician you take it, because it is an androgen precursor and it shows up in the results they are reading.

DHEA, boron and pregnenolone

Will CPAP raise my testosterone?

CPAP does not reliably raise testosterone: the evidence that treating obstructive sleep apnea with airway pressure raises the hormone is mixed. CPAP reliably improves sleep quality and daytime sleepiness, and weight loss appears to do more for the hormone itself than the machine does — but the symptoms that sent you looking at testosterone in the first place, the fatigue and flat mood and poor concentration, are the ones treating the apnea addresses well. Untreated sleep apnea is worth treating on its own cardiovascular merits whatever happens to the number, and testosterone therapy can make it worse.

What sleep apnea does to testosterone

Results vary. Clinical trial results apply only to the FDA-approved branded medication specifically identified and do not apply to compounded medications. All medications must be prescribed by a licensed provider based on medical necessity.