Testosterone Replacement Therapy for Erectile Dysfunction

Testosterone Replacement Therapy for Erectile Dysfunction: What You Need to Know

Published: 15 October 2026

Testosterone replacement therapy for erectile dysfunction is sometimes considered when low testosterone (hypogonadism) is confirmed and contributing to erection problems. However, most men with erectile dysfunction have normal testosterone levels, and in those cases testosterone therapy will not improve erections [1][2]. If blood tests confirm genuinely low testosterone alongside symptoms such as reduced libido, fatigue, and erectile difficulties, replacing testosterone may help—but it is not a first-line treatment for ED on its own.

How Does Testosterone Replacement Therapy for Erectile Dysfunction Work?

Testosterone is a hormone that plays a role in sexual desire (libido), mood, energy, and the health of blood vessels and nerves involved in erections [1]. When testosterone levels fall significantly below the normal range—a condition called hypogonadism—some men experience reduced interest in sex and difficulty achieving or maintaining erections. Testosterone replacement therapy (TRT) aims to restore testosterone to normal physiological levels using gels, patches, injections, or (less commonly) oral preparations [2].

It is important to understand that testosterone replacement therapy for erectile dysfunction only works if low testosterone is genuinely part of the problem [2]. Most men with ED have testosterone levels within the normal range, and in those cases TRT will not improve erections and is not recommended [1][2]. Before starting TRT, your doctor will arrange blood tests (usually taken in the morning when testosterone is highest) to confirm low levels on at least two separate occasions, and will also check for underlying causes such as obesity, diabetes, or pituitary disorders [2].

Even when testosterone is low, TRT may improve libido and energy more reliably than it improves the physical ability to get an erection [2]. Many men with confirmed low testosterone and ED will still need a PDE5 inhibitor tablet (such as sildenafil or tadalafil) to achieve erections firm enough for sex [2]. TRT and PDE5 inhibitors can be used together safely under medical supervision.

Who May Be Suitable for Testosterone Replacement Therapy?

Testosterone replacement therapy is only appropriate for men who have been diagnosed with hypogonadism—persistently low testosterone confirmed by blood tests—and who have symptoms such as reduced libido, fatigue, low mood, or erectile dysfunction [2]. It is not suitable for men whose testosterone levels are in the normal range, even if they have ED, because it will not help and may cause unnecessary side effects [1][2].

Your GP or specialist will assess whether your symptoms and blood results fit the diagnosis of hypogonadism. They will also check for conditions that can lower testosterone, such as obesity, type 2 diabetes, chronic illness, or problems with the pituitary gland [2]. Losing weight, improving diet and exercise, managing diabetes, and reducing alcohol can sometimes raise testosterone naturally and should be tried first [1][2].

TRT is not suitable for men with prostate cancer, breast cancer, untreated severe obstructive sleep apnoea, uncontrolled heart failure, or a high red blood cell count (polycythaemia) [2]. Your doctor will also consider your age, overall health, and whether you are planning to father children, because TRT can reduce sperm production [2]. If you have erectile dysfunction but normal testosterone, PDE5 inhibitor tablets are the recommended first-line treatment and are much more effective for improving erections [1][2].

When to See Your GP About Erectile Dysfunction

If you are experiencing persistent erection problems, it is important to see your GP rather than self-diagnosing low testosterone [1]. Erectile dysfunction can be an early warning sign of cardiovascular disease, diabetes, or high blood pressure, and your doctor will want to check your overall health [1][2]. They will ask about your symptoms, medical history, and lifestyle, and may arrange blood tests to check testosterone, blood sugar, cholesterol, and other markers. Most men with ED do not have low testosterone, and the majority respond well to PDE5 inhibitor tablets without needing hormone therapy [1][2].

Effectiveness of Testosterone Replacement Therapy for Erectile Dysfunction

The effectiveness of testosterone replacement therapy for erectile dysfunction depends entirely on whether low testosterone is contributing to the problem [2]. In men with confirmed hypogonadism, TRT can improve libido, energy, and mood, and may lead to some improvement in erectile function—but the effect on erections is often modest and less predictable than the effect on sexual desire [2].

Clinical evidence shows that TRT is most helpful for men whose ED is accompanied by low libido and fatigue due to genuinely low testosterone [2]. However, even in these men, TRT alone may not be enough to restore firm erections, and many will still benefit from adding a PDE5 inhibitor such as sildenafil or tadalafil [2]. In men with normal testosterone levels, TRT does not improve erectile function and is not recommended [1][2].

It can take several weeks to months to notice the full benefits of testosterone replacement, and regular blood tests and monitoring are needed to ensure levels are in the target range and to check for side effects [2]. If you have been prescribed TRT for confirmed low testosterone and are still experiencing erectile difficulties, your doctor may recommend combining it with a PDE5 inhibitor, which works by a different mechanism to help blood flow into the penis during sexual stimulation [1][2].

Side Effects and Risks of Testosterone Replacement Therapy

Testosterone replacement therapy can cause side effects, and long-term use requires regular monitoring by your doctor [2]. Common side effects include acne, oily skin, increased body hair, mood changes, and breast tenderness or enlargement (gynaecomastia) [2]. TRT can also increase red blood cell production, which may raise the risk of blood clots, so your doctor will check your full blood count regularly [2].

Testosterone replacement can reduce sperm production and fertility, so it is not suitable if you are planning to father children [2]. It may also worsen untreated sleep apnoea and can affect cholesterol levels [2]. There has been concern about whether TRT increases the risk of cardiovascular events or prostate problems, and while the evidence is not conclusive, your doctor will assess your individual risk and monitor you closely, especially if you have existing heart disease or are over 50 [2].

Testosterone gels and patches can cause skin irritation at the application site, and gels carry a risk of transferring testosterone to partners or children through skin contact, so careful handwashing and covering the area is essential [2]. Injections can cause pain or swelling at the injection site. If you experience chest pain, shortness of breath, leg swelling, sudden severe headache, or vision changes while on TRT, seek urgent medical help [2].

Monitoring and Follow-Up

If you are prescribed testosterone replacement therapy, your doctor will arrange regular follow-up appointments and blood tests to check your testosterone levels, full blood count, liver function, cholesterol, and prostate-specific antigen (PSA) [2]. Monitoring is usually more frequent in the first year and then annually once stable [2]. Your doctor will also ask about symptoms, side effects, and whether your sexual function and energy have improved. Never stop or adjust TRT without medical advice, and always inform any healthcare professional that you are taking it.

NHS Availability of Testosterone Replacement Therapy for Erectile Dysfunction

Testosterone replacement therapy is available on the NHS for men with confirmed hypogonadism (persistently low testosterone levels with symptoms), but it is not routinely prescribed solely for erectile dysfunction unless blood tests confirm low testosterone [2]. Your GP will arrange the necessary blood tests and, if hypogonadism is confirmed, may initiate treatment or refer you to an endocrinologist or urologist for specialist assessment and ongoing management [2].

NHS prescribing of TRT requires clear evidence of low testosterone on at least two morning blood tests, along with symptoms such as reduced libido, fatigue, low mood, or erectile difficulties [2]. If your testosterone is in the normal range, TRT will not be offered, and you will be advised to try PDE5 inhibitor tablets instead, which are the recommended first-line treatment for erectile dysfunction and are also available on the NHS in certain circumstances (such as diabetes, prostate cancer treatment, or other specified conditions) [1][2].

Private prescriptions for testosterone replacement are also available, but you should only use TRT under the supervision of a qualified doctor who has confirmed low testosterone with blood tests and ruled out underlying causes [2]. Self-prescribing or buying testosterone online without proper medical assessment is unsafe and can cause serious harm [2]. If you have erectile dysfunction, start by seeing your GP for a full assessment, as most men do not need testosterone and will respond well to safer, more effective treatments such as PDE5 inhibitors [1][2].

How Testosterone Replacement Therapy Compares with Oral ED Tablets

For the vast majority of men with erectile dysfunction, oral PDE5 inhibitor tablets—such as sildenafil (Viagra), tadalafil (Cialis), vardenafil (Levitra), and avanafil (Spedra)—are the most effective and safest first-line treatment [1][2]. These tablets work by increasing blood flow to the penis during sexual stimulation, and clinical trials show they help around 70–80% of men achieve erections firm enough for sex [9]. They do not require blood tests, work within 15 minutes to an hour, and are taken only when needed (or daily in the case of low-dose tadalafil) [1][2].

In contrast, testosterone replacement therapy for erectile dysfunction is only appropriate for the small proportion of men who have confirmed low testosterone (hypogonadism) [2]. Even in those men, TRT may improve libido and energy more than it improves the physical ability to get an erection, and many will still need a PDE5 inhibitor to achieve satisfactory erections [2]. TRT requires long-term daily or regular use, ongoing blood test monitoring, and carries risks such as reduced fertility, increased red blood cells, and potential cardiovascular or prostate effects [2].

If you have normal testosterone levels, PDE5 inhibitors are far more effective and safer than TRT for treating erectile dysfunction [1][2]. If you have low testosterone confirmed by blood tests, your doctor may recommend TRT to address symptoms such as low libido and fatigue, but you may still benefit from adding a PDE5 inhibitor for erections [2]. The two treatments work by different mechanisms and can be used together safely under medical supervision. At Cured Pharmacy, our UK prescribers can assess your suitability for PDE5 inhibitor tablets through a confidential online consultation, with discreet delivery if treatment is appropriate.

Choosing the Right Treatment for You

The right treatment for erectile dysfunction depends on the underlying cause, your overall health, and your personal preferences [1][2]. Most men with ED have normal testosterone and will respond well to PDE5 inhibitor tablets, which are effective, well-tolerated, and taken only when needed [1][2]. If you have symptoms of low testosterone (reduced libido, fatigue, low mood) alongside ED, ask your GP for a blood test. If low testosterone is confirmed, your doctor will discuss whether TRT is appropriate and whether you might also benefit from a PDE5 inhibitor. Never start testosterone or any ED treatment without proper medical assessment, as erectile dysfunction can be a sign of serious underlying health conditions that need investigation and management [1][2].

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 15 October 2026]
2. National Institute for Health and Care Excellence. (n.d.). Erectile dysfunction. Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/erectile-dysfunction/ [accessed 15 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 15 October 2026]
4. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 15 October 2026]
5. Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 15 October 2026]
6. Joint Formulary Committee. (n.d.). Avanafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/avanafil/ [accessed 15 October 2026]
7. Goldstein, I., Lue, T. F., Padma-Nathan, H., Rosen, R. C., Steers, W. D., & Wicker, P. A. (1998). Oral sildenafil in the treatment of erectile dysfunction. New England Journal of Medicine, 338(20), 1397–1404. https://pubmed.ncbi.nlm.nih.gov/9580646/ [accessed 15 October 2026]
8. National Institute for Health and Care Excellence. (2014). Erectile dysfunction: avanafil (ESNM45). https://www.nice.org.uk/advice/esnm45 [accessed 15 October 2026]

Information on this page is for educational purposes only and is not medical advice. Prescription treatments require clinical assessment by a UK-registered prescriber. Always consult a qualified healthcare professional before starting or changing any medication.