Symptoms & Diagnosis

TRT and Erectile Dysfunction: What Testosterone Does and Does Not Treat

Why testosterone improves desire more reliably than erections, and why erectile difficulty deserves proper investigation

Sexual Performance - TRT and Erectile Dysfunction: Can Testosterone Therapy Improve Your Performance?
Medically reviewed by Medical Director · MUDr 2012, Charles University in Prague – First Faculty of Medicine GMC No. 7404207 Last updated: 19 August 2026
Written by GP and Health Data Scientist · MB ChB 2015, University of Liverpool · MSc Health Data Science, University College London GMC No. 7492303

Medical Summary

Erectile difficulties and a flat sex drive are among the most common reasons men look into testosterone, and they are two different problems that often get treated as one. The evidence separates them fairly clearly. Testosterone treatment reliably improves sexual desire in men who have genuine deficiency, and it improves erectile function in that same group. What it does not do is act as a treatment for erectile dysfunction in general.

The single most useful finding for anyone weighing this up comes from a randomised trial: in men who had both erectile dysfunction and low testosterone, standard tablet treatment with a phosphodiesterase-5 inhibitor produced substantial improvement, and adding testosterone on top produced no further improvement in erectile function compared with placebo [1]. Testosterone is not the first-line answer to an erection problem, even when testosterone is low.

There is a more important reason to take erectile difficulty seriously than the inconvenience of it. British guidance notes that the link between morning erections and cardiovascular disease is well established, and it recommends asking about them even in men who are not currently in a physical relationship [2]. Erectile dysfunction can be an early warning of vascular disease. Treating the symptom while ignoring what it might be signalling is the mistake we most want to avoid.

Desire and erections are not the same problem

It is worth being precise about terms, because the distinction changes what treatment is appropriate. Libido is the drive: the frequency of sexual thoughts, interest in sex, responsiveness to a partner. Erectile function is the mechanics: whether the blood flow and nerve signalling produce and maintain an erection. Testosterone is heavily involved in the first and only partly involved in the second.

In the Testosterone Trials, a coordinated set of seven placebo-controlled trials in men aged 65 and over with two morning fasting readings below 275 ng/dL, treatment of men with low libido significantly improved overall sexual activity, sexual desire and erectile function. It increased spontaneous sexual thoughts, attentiveness to erotic cues, the duration and frequency of night-time erections and ejaculate volume [3]. Those are real and meaningful gains in the right group of men.

Two boundaries came out of the same body of work. Testosterone does not improve sexual function in men whose testosterone is normal and who do not have sexual symptoms, and it does not improve ejaculatory function in men with an ejaculatory disorder even when testosterone is low [3]. The benefit is specific to men who are genuinely deficient and who have the symptoms that go with it.

What actually points to a hormonal cause

Erectile dysfunction on its own is a weak signal for testosterone deficiency, because it has so many other causes. What raises the suspicion is the combination. The Fourth International Consultation for Sexual Medicine, quoted in British guidance, puts it this way: low sexual desire, reduced morning and night-time erections and erectile dysfunction are prominent presenting symptoms, and they are particularly suggestive of testosterone deficiency when they occur together [2].

Alongside those sit the less specific symptoms: fatigue, disturbed sleep, loss of physical strength, reduced energy and motivation, and low mood [2]. On their own, none of them means much. A man reporting reduced desire, fewer morning erections, difficulty maintaining an erection and persistent tiredness is describing a pattern worth investigating properly. Our page on low testosterone symptoms goes through the full picture.

A UK survey of community-dwelling men found 31 per cent reported low libido and 27 per cent reported reduced erectile strength, with men over 50 having roughly one and a half to two times the odds of screening positive compared with men under 40 [4]. These symptoms are common. That is a reason for proper assessment, not a reason to assume every case is hormonal.

The other causes that deserve ruling out first

An honest consultation about erectile difficulty spends most of its time on things other than testosterone. Vascular disease, diabetes, high blood pressure, smoking, excess alcohol, depression, anxiety, relationship difficulty and medication side effects are all well-recognised contributors, and several are more common than deficiency.

Two drug-related causes are worth singling out because they are frequently missed. British guidance notes that men treated with finasteride or dutasteride, prescribed for benign prostate enlargement or male pattern hair loss, are placed in a state of androgen deficiency and are at high risk of developing erectile dysfunction, and that a similar syndrome of prolonged sexual dysfunction is seen with isotretinoin used for acne [2]. The guidance advises assessing men before prescribing these long term. Separately, between a quarter and four-fifths of men on long-term prescribed opioids have hypogonadism depending on the drug and dose, and routine screening of that group is recommended [2]. Oral glucocorticoids, anticonvulsants and antipsychotics can also suppress testosterone [2].

If any of those apply to you, they belong in the conversation before a prescription is considered. Sometimes the right answer is a change to existing medication rather than the addition of a new one, and that is a decision for the clinician who manages that medication.

Why the low reading might not be the root problem

Most middle-aged and older men with low testosterone have low or inappropriately normal luteinising hormone, the pattern called secondary hypogonadism, and it is typically associated with obesity and other health conditions rather than with a failure of the testicles [3]. Primary hypogonadism, where the testicles themselves are underactive and luteinising hormone is raised, is less common and tracks more closely with age.

That distinction matters because the secondary pattern is often partly reversible. Weight, untreated sleep apnoea, medication and other illness can all suppress the axis, and addressing them can lift testosterone without replacement. It is also why measuring gonadotropins is part of a proper work-up rather than an optional extra: British guidance is explicit that assessing them is required to determine the origin of the deficiency [2]. Our page on testosterone and sleep apnoea covers one of the commonest reversible contributors.

Diagnosis itself requires both halves. Characteristic signs and symptoms must be present, and total or free testosterone must be reduced, confirmed on separate occasions [2]. A single number without symptoms does not make a diagnosis, and symptoms without biochemistry do not either. Our page on normal testosterone levels explains how results are interpreted, including why free testosterone has to be calculated alongside sex hormone binding globulin.

Where testosterone sits alongside standard erection treatment

This is the part of the subject where commercial interest and evidence most often part company, so it is worth stating plainly. In a parallel randomised trial in men with erectile dysfunction and low testosterone, adding testosterone to a phosphodiesterase-5 inhibitor did not improve erectile function beyond what the tablet alone achieved [1]. The finding is reported in a review written by a leading testosterone researcher who discloses research funding from a testosterone manufacturer, which makes it harder to dismiss as scepticism [3].

The practical reading is that if your primary complaint is erections, established treatment for erectile dysfunction is where to start, and that is a conversation for a GP or a sexual medicine service. If your primary complaint is that desire has gone, and you have the wider symptom pattern and confirmed low readings, testosterone addresses something the tablets do not touch. Many men have both, and in that case both may be appropriate, but they are treating different things.

This is also why we would rather a man came to us with a symptom picture than with a purchase in mind. Where the assessment points away from a hormonal cause, we can arrange a private GP appointment through our sister service so the right investigation happens.

Erectile difficulty as a cardiovascular warning

Of everything on this page, this is the section we would most want a man to read. An erection depends on healthy blood vessels and intact nerve signalling. The arteries involved are small, which means they can show the effects of vascular disease earlier than the larger arteries supplying the heart. Difficulty with erections can therefore appear before any cardiac symptom does.

British guidance treats this as established, which is why it advises asking about morning erections specifically, and asking even of men who are not currently in a physical relationship, precisely because the link with cardiovascular disease is well recognised [2]. The same guidance lists hypertension, coronary artery disease, cerebrovascular disease, chronic heart failure and atrial fibrillation among the conditions in which testosterone deficiency is more prevalent, alongside obesity, metabolic syndrome and type 2 diabetes [2].

The clinical implication is that a new erectile problem is a reason to have blood pressure, cholesterol, blood glucose and weight assessed, whatever happens with hormones. That is not a diversion from the presenting complaint. In some men it is the most valuable thing to come out of the consultation, and it is one of the reasons we regard an erectile symptom as something to investigate rather than something to medicate quickly.

Why so few men get properly assessed

The UK survey data show a substantial gap between symptoms and diagnosis. Men reported the symptoms in numbers far exceeding those who had ever been assessed, and the barriers they identified were lack of awareness, cost and stigma [4]. Sexual symptoms carry more embarrassment than most, and they are the ones men are least likely to raise in a ten-minute appointment.

There is also a structural issue. Testosterone is not part of routine blood panels for men, for defensible reasons: it requires careful timing, free testosterone has to be calculated rather than measured directly, and results fluctuate enough that a single reading can mislead. The consequence is that the test is generally ordered only when a man reports specific symptoms. If he does not mention them, it does not happen. Our page on testosterone testing explains what is measured and why timing matters.

Reducing the barriers is the reason our initial consultation carries no charge and the reason we will review existing testosterone blood work at no cost. That is not the same as lowering the clinical threshold. The assessment is the same either way, and it still requires symptoms plus confirmed biochemistry on two separate tests before anyone talks about treatment.

The risks that belong in this conversation

Treatment carries its own considerations, and a man weighing up a sexual symptom deserves them stated rather than buried. The most frequent adverse effect of testosterone treatment is erythrocytosis, an increase in the concentration of red cells in the blood, which is why a full blood count forms part of baseline testing and ongoing monitoring [3]. Other recognised effects include acne, reduced sperm production and, in men with existing prostate cancer, growth of that cancer [3].

Fertility deserves particular emphasis here, because it is directly relevant to men thinking about sexual health. Testosterone treatment suppresses sperm production. A man who wants children in the foreseeable future needs that discussed before starting, not afterwards.

On cardiovascular safety, the largest trial to date found treatment was no worse than placebo for heart attack, stroke and cardiovascular death in 5,246 men at high cardiovascular risk, while finding a higher incidence of atrial fibrillation, acute kidney injury and pulmonary embolism [5]. We cover that evidence in full on testosterone and heart health, and the wider risk picture on TRT side effects.

How we assess sexual symptoms at MYTRT

The framework we work to mirrors the one set out in the endocrine literature: establish whether there is clear evidence of deficiency using reliable measurement of total and free testosterone, weigh the burden of symptoms against the potential benefits and the uncertainty about long-term effects, and check for conditions that would increase the risk of harm, such as prostate cancer, a raised red cell concentration, heart failure or a tendency to clot [3]. Where treatment is agreed, it comes with a monitoring plan rather than a repeat prescription.

In practice that means the consultation covers your symptoms across desire, erections and morning erections; your cardiovascular and metabolic history; your medication, including finasteride, opioids and anything else on the list above; your sleep; your weight; and your plans regarding fertility. Blood work is confirmed on two separate tests before any diagnosis is made, and prescribing and final dosing rest with the prescribing clinicians and our regulated pharmacy partner.

Sometimes the outcome of that assessment is that testosterone is not the answer. We would rather tell a man that than sell him a subscription he does not need. If you want to understand what treatment involves when it is appropriate, what is TRT explains it, and is TRT safe sets out the safety picture in full.

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References

  1. Spitzer M, Basaria S, Travison TG, et al. Effect of testosterone replacement on response to sildenafil citrate in men with erectile dysfunction: a parallel, randomized trial. Annals of Internal Medicine 2012;157(10):681-691. View
  2. Hackett G, Kirby M, Rees RW, et al. The British Society for Sexual Medicine Guidelines on Male Adult Testosterone Deficiency, with Statements for Practice. World Journal of Men’s Health 2023;41(3):508-537. View
  3. Bhasin S. Testosterone replacement in aging men: an evidence-based patient-centric perspective. Journal of Clinical Investigation 2021;131(4):e146607. View
  4. Liu VN, et al. Awareness and prevalence of the symptoms of testosterone deficiency among community-dwelling men in the UK: a cross-sectional survey. BMJ Open 2025;15(7):e094145. View
  5. Lincoff AM, Bhasin S, Flevaris P, et al. Cardiovascular Safety of Testosterone-Replacement Therapy. New England Journal of Medicine 2023;389(2):107-117. View

Your Questions Answered

Our team has significant expertise and experience in men's health.

Not on its own, and not usually as a first step. In a randomised trial of men who had both erectile dysfunction and low testosterone, treatment with a phosphodiesterase-5 inhibitor produced substantial improvement in erectile function, and adding testosterone gave no further benefit compared with placebo. Testosterone reliably improves sexual desire in men who are genuinely deficient, and improves erectile function in that group, but it is not a treatment for erectile dysfunction in general. If erections are your main concern, established treatment for erectile dysfunction is the place to start.

It can contribute, but it is rarely the only factor and often not the main one. Vascular disease, diabetes, high blood pressure, smoking, excess alcohol, depression, anxiety, relationship difficulties and medication side effects are all well-recognised causes, and several are more common than testosterone deficiency. What raises suspicion of a hormonal cause is the combination of low sexual desire, reduced morning and night-time erections and erectile difficulty occurring together, rather than erectile difficulty alone.

Yes, and this is the most important reason not to ignore it. An erection depends on healthy blood vessels and intact nerve signalling, and the arteries involved are small enough to show the effects of vascular disease earlier than the larger arteries supplying the heart. British guidance regards the link between morning erections and cardiovascular disease as well established and recommends asking about them even in men who are not currently in a physical relationship. A new erectile problem is a reason to have blood pressure, cholesterol, glucose and weight assessed.

Because they are different mechanisms. Testosterone acts in the brain to stimulate sexual desire, so restoring a deficient level increases spontaneous sexual thoughts, interest in sex and responsiveness to erotic cues. Erections depend more on blood flow and nerve signalling, which testosterone influences but does not control. In the Testosterone Trials, treatment of men with low libido significantly improved sexual activity, desire and erectile function, but testosterone added nothing to standard erection treatment when tested directly.

It is worth checking, because several common medicines are implicated and this is frequently missed. British guidance notes that finasteride and dutasteride, prescribed for prostate enlargement and male pattern hair loss, place men in a state of androgen deficiency and at high risk of erectile dysfunction, and that a similar syndrome of prolonged sexual dysfunction is seen with isotretinoin used for acne. Between a quarter and four-fifths of men on long-term prescribed opioids have hypogonadism. Oral glucocorticoids, anticonvulsants and antipsychotics can also suppress testosterone.

Yes. Testosterone treatment suppresses sperm production, which is a particularly relevant consideration for men presenting with sexual symptoms. If you may want children in the foreseeable future, this needs discussing before treatment starts rather than afterwards. There are alternative approaches for men who wish to preserve fertility, and that conversation should happen at the assessment stage. Our page on male fertility testing covers how fertility is assessed.

Yes. Diagnosis requires characteristic signs and symptoms together with a reduced total or free testosterone level, confirmed on separate occasions. A single result is not enough, because testosterone fluctuates through the day and can be temporarily suppressed by illness, poor sleep, stress or medication. Assessment of gonadotropins is also required to determine whether the problem originates in the testicles or in the pituitary, which affects what treatment is appropriate. Our page on normal testosterone levels explains how results are interpreted.

Primary means the testicles themselves are underactive, with luteinising hormone raised as the pituitary tries to compensate, and it tracks more closely with age. Secondary means the signal from the pituitary is reduced, so luteinising hormone is low or inappropriately normal, and it is typically associated with obesity and other health conditions. Most middle-aged and older men with low testosterone have the secondary pattern, which matters because it is often partly reversible by addressing weight, sleep or medication.

More common than the diagnosis rate suggests. A survey of community-dwelling UK men found 31 per cent reported low libido and 27 per cent reported reduced erectile strength, with men over 50 having roughly one and a half to two times the odds of screening positive compared with men under 40. The barriers men identified were lack of awareness, cost and stigma. Sexual symptoms carry more embarrassment than most, and they are the ones least likely to be raised in a short appointment.

For defensible clinical reasons. The test requires careful timing because levels fluctuate substantially through the day, free testosterone has to be calculated alongside sex hormone binding globulin rather than measured directly, and a single reading can mislead. Routine screening of men without symptoms carries a real risk of false positives from temporary factors such as stress or poor sleep, which can lead to unnecessary treatment. The consequence is that the test is generally ordered only when a man reports specific symptoms, so those symptoms need mentioning.

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