Can Low Testosterone Cause Erectile Dysfunction?

If you've searched for this, you've probably already wondered whether "it's just testosterone" and hoped for a simple fix.

It's a reasonable thing to wonder.

Low testosterone is a real, measurable, treatable condition, and it does contribute to erectile problems in a meaningful number of men.

But testosterone on its own is a modest fix for erections, even when it's genuinely low.

Its strongest effect is on libido, energy, and mood. For the mechanics of getting and keeping an erection, a PDE5 inhibitor (the tablets in Viagra, Cialis, and similar medicines) usually does more of the heavy lifting, and prescribers typically prescribe the two together.

In this guide, we'll walk you through how testosterone actually affects erections, what a proper diagnosis looks like, and what treatment realistically achieves.

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Testosterone works on erections in a few different ways, and it helps to know which one applies to you.

It drives desire. This is the clearest link. Testosterone fuels sex drive, and low libido combined with fewer morning erections and general ED is the strongest sign that testosterone is genuinely part of the picture, more specific than fatigue or low mood on their own.

It supports the chemistry of an erection. Testosterone helps maintain the nerve signalling and blood vessel response inside the penis that lets an erection happen in the first place. It also affects how well the tissue responds to PDE5 inhibitors, which is part of why very low testosterone can make ED tablets work less well than expected.

It maintains the tissue itself. Over the longer term, testosterone helps keep the smooth muscle and blood vessels in penile tissue healthy. When testosterone stays low for a long time, that tissue can change in ways that make erections harder to achieve, independent of anything to do with mood or desire.

The chemistry and tissue-health effects described above are well established from tissue and animal studies, so think of testosterone as necessary for normal erections rather than the single switch that turns them on or off.

Vascular health, blood flow, nerve function, and psychological factors all matter too, often more than testosterone does.

More common than most men expect, but far from universal.

The pattern that stands out from the research: Low testosterone becomes a lot more likely if you also have type 2 diabetes, are significantly overweight, or have another chronic health condition.

On its own, age doesn't automatically mean falling testosterone.

Most men keep normal levels well into later life; it's usually the health conditions that come with age, not age itself, that push testosterone down.

A few symptoms together point more strongly at testosterone than any one on its own.

The combination that matters most:

When these three show up together, that's the pattern UK prescribers treat as the clearest signal to get tested.

Other symptoms worth mentioning to your GP or prescriber:

Things that increase the risk for low testosterone:

If you recognise several of these, particularly the low libido and morning erection pattern, that's a good reason to get your testosterone checked properly.

Most low testosterone is manageable and not urgent. A small number of signs mean you should consult your prescriber quickly.

See a doctor promptly if you notice:

Our guide on when to see a doctor for erectile dysfunction explains this in more detail.

One blood test isn't enough. Testosterone follows a daily rhythm: It's highest first thing in the morning and lower by the evening, though this effect is smaller in older men than in younger men.

It also dips after a sugary meal, and gets knocked around by poor sleep, illness, or a night shift at work.

Both the British Society for Sexual Medicine and the Society for Endocrinology recommend confirming a low result with a second test.

BSSM suggests doing this about four weeks apart; the Society for Endocrinology doesn't specify an exact interval, just that it should be a separate occasion.

What the numbers mean. UK prescribers measure total testosterone measured in nmol/L:

If your level sits in the borderline range, your prescriber may also check:

These help distinguish a testicular problem from a pituitary one, and rule out anything else that needs a different approach.

There isn't a standalone NICE guideline on testosterone deficiency as its own condition.

But NICE's Clinical Knowledge Summary on erectile dysfunction does recommend testosterone testing as a routine part of assessing ED, using the same before-11 AM, two-test approach described above, and it points prescribers towards British Society for Sexual Medicine guidance for what to do with the result.

Sometimes, but usually not completely.

Across the clinical trial evidence, testosterone treatment improves erectile function scores by a small amount on average, more noticeably when starting testosterone was clearly low (below 8 nmol/L) and less so when it was only borderline.

The most rigorous recent study, the TRAVERSE trial published in 2024, found testosterone treatment clearly improved sex drive and general hypogonadal symptoms, but didn't produce a statistically significant improvement in erectile function itself.

That study specifically enrolled men with heart disease or a high cardiovascular risk, and this part of the study only included men who'd noticed low libido at the start, which likely affected the result.

It's still a useful reality check against the idea that testosterone alone reliably fixes erections.

Sexual desire tends to improve within about six weeks of starting testosterone treatment.

Erections can take longer, and prescribers usually recommend giving it a full six months before judging whether it's worked.

This is where OnlineClinic can help immediately, even before any testosterone question is settled.

Confirming and starting testosterone treatment properly needs two lab-quality blood tests, a physical examination, and an ongoing monitoring plan (regular blood counts and PSA checks, for as long as you're on treatment).

That's more than a quick online questionnaire can responsibly cover.

Some dedicated UK testosterone clinics do offer this remotely, but only by building in the extra steps: accredited lab testing, a proper monitoring plan, and ongoing follow-up.

That's a different, dedicated service to the kind of ED consultation we offer today.

If we think low testosterone might be part of your picture, we'll flag it clearly and point you towards your GP or a testosterone-specific clinic for the testing and monitoring that treatment requires.

What we can do straight away is treat the erectile dysfunction itself.

A short online consultation with one of our GMC-registered prescribers is often enough to start a PDE5 inhibitor like sildenafil or tadalafil, the same medicines used alongside testosterone treatment in the guidance above.

You don't need to wait for a testosterone result to get that sorted.

If you and your prescriber do move ahead with testosterone treatment, a few points are worth understanding upfront.

It can affect fertility. Testosterone treatment switches off your body's own hormone signal to the testes, which usually reduces or stops sperm production. Research suggests that for most men (around 60 to 70%), sperm production recovers within about a year of stopping, though it can take longer for some.

Research suggests that for most men (around 60 to 70%), sperm production recovers within about a year of stopping, though it can take longer for some.

If you're hoping to start or grow a family in the near future, say so before starting treatment. There are alternative approaches your prescriber can discuss.

It needs monitoring. Blood counts and PSA get checked at 3, 6, and 12 months, then yearly. This picks up two of the more common side effects early: a thickening of the blood (raised haematocrit) and changes worth discussing with a urologist.

It isn't suitable for everyone. Testosterone treatment cannot be used if you have known or suspected prostate cancer or breast cancer, or (for injectable forms) a past or present liver tumour.

Some men previously treated for low-risk prostate cancer may still be considered by a specialist on a case-by-case basis.

Untreated severe sleep apnoea, a very high red blood cell count, and a personal or family history of blood clots are reasons a prescriber may advise against treatment, or monitor you more closely.

UK licensing hasn't changed the way US headlines might suggest. You may see reports of US label changes: In February 2025, the FDA removed its heart-risk warning and added new blood pressure warnings, and in June 2026, it proposed further changes, including narrowing the prostate cancer restriction.

None of this changes UK licensing, which the MHRA sets separately. The MHRA's most recent UK safety update on testosterone (January 2023) was about accidental skin-to-skin transfer of testosterone gel to children and partners.

Whatever the underlying cause for ED, the first-line treatment for most men is the same class of medication, PDE5 inhibitors, which work by improving blood flow to the penis.

In the UK, four treatment options are licensed for ED: Viagra (sildenafil), Cialis (tadalafil), vardenafil, and Spedra (avanafil).

Apart from the above-mentioned treatments, UK also has a Generic Impotence Trial Pack, which includes 4 tablets of tadalafil 10mg, 4 tablets of vardenafil 10mg, and 4 tablets of sildenafil 10mg. The prices for the same starts from £49.99.

Two are available without a prescription, after a short pharmacist consultation: Viagra Connect (sildenafil) and Cialis Together (tadalafil).

Which one suits you often comes down to how long you want it to last and how you'd like to plan around it, rather than the underlying cause.

PDE5 inhibitors should not be taken alongside nitrate medications (commonly prescribed for angina) or recreational nitrates ('poppers'), as the combination can cause a dangerous drop in blood pressure.

Tell your prescriber about all medications you're taking, including any for blood pressure or chest pain, before starting treatment.

Our guides on Viagra vs Sildenafil and Cialis daily vs on-demand walk through the practical differences.

Addressing an underlying cause, whether that's blood pressure, weight, alcohol, stress or a medication switch, often improves things further, alongside or instead of tablets.

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