ED and low testosterone: how they are linked

Testosterone gets a lot of attention online, and many men assume it must be behind their erection problems. Sometimes it plays a part, but often it does not. This page explains how the two are linked, who should be tested, and what happens next. For the bigger picture of what causes ED, see what causes erectile dysfunction.

How are erectile dysfunction and low testosterone linked?

Testosterone mainly controls desire, while erections depend mostly on blood flow and nerves. Low testosterone can contribute to ED, but most men with ED have normal testosterone.

Testosterone works in the background. It drives libido, supports the nerve signals and nitric oxide production that start an erection, and helps maintain the erectile tissue. When levels are very low, desire falls and erections can become weaker and less frequent, especially morning erections.

But the main engine of an erection is blood flow. That is why the most common causes of ED are high blood pressure, diabetes, high cholesterol and smoking, not hormones. The two often travel together: obesity, type 2 diabetes and poor sleep all lower testosterone and damage blood vessels at the same time.

Low testosterone also matters for treatment. Some men whose ED does not respond to a PDE5 inhibitor such as sildenafil (Viagra) or tadalafil (Cialis) turn out to have low testosterone, and correcting it can help the medicine work better.

What are the symptoms of low testosterone?

The most typical symptom is low sexual desire, often with fewer morning erections, tiredness and low mood. Doctors look for a pattern of symptoms rather than any single one.

Common symptoms and signs:

• Low interest in sex.
• Fewer or weaker morning and spontaneous erections.
• Erectile dysfunction.
• Tiredness and low energy.
• Low mood, irritability or poor concentration.
• Loss of muscle and strength, and more body fat, especially around the waist.
• In longer-standing cases, reduced body hair and thinning bones.

All of these have other causes, from stress and depression to thyroid problems and poor sleep. That is why a blood test is needed before anyone can say testosterone is the problem.

Who should have a testosterone test?

Testing makes sense if you have ED together with low desire, or other symptoms of low testosterone. The EAU recommends checking morning testosterone in men with ED as part of the basic workup, especially when desire is also low.

Testing is also worth considering if you:

• Have type 2 diabetes or obesity, both of which are linked with lower testosterone.
• Have taken anabolic steroids, which can shut down your own production.
• Use long-term opioid painkillers.
• Have had a testicular injury, mumps affecting the testicles, or chemotherapy.
• Work long-term night shifts with poor sleep. Shift work disrupts the hormone rhythm, and in one US study of shift workers, testosterone treatment improved erectile scores in men with shift work sleep disorder.
• Find that a PDE5 inhibitor prescribed by your doctor is not working.

Testing without symptoms, or because a supplement advert suggests it, is generally not recommended.

Why is the testosterone blood test taken in the morning?

Testosterone peaks in the early morning and falls through the day, so a test taken in the afternoon can look low in a perfectly healthy man. Guidelines recommend an early-morning test, and a second morning test to confirm any low result.

What to expect:

• Timing. Book the blood draw for early morning, ideally before about 10 am. Many hospital labs and diagnostic centres in the Philippines open early for fasting tests, so it can be done with a fasting blood sugar and cholesterol at the same visit.
• Night-shift workers. If you work nights, tell your doctor. Your body clock is shifted, so the doctor may advise when to schedule the test.
• Two tests. The American Urological Association recommends two early-morning total testosterone measurements on separate days before making a diagnosis.
• The threshold. The AUA uses a total testosterone below 300 ng/dL as a reasonable cut-off to support the diagnosis, alongside symptoms. Labs may report results in nmol/L; about 10.4 nmol/L is the equivalent.
• Extra tests. If testosterone is low, your doctor may check LH, prolactin, and sometimes free testosterone and thyroid function, to find out why.

A single low number is not a diagnosis. Illness, poor sleep the night before, heavy drinking or an afternoon test can all lower a reading temporarily.

What can raise testosterone naturally?

Losing excess weight, sleeping well, exercising and cutting heavy drinking can all raise low testosterone in many men. These changes also improve blood flow, so they help erections in two ways.

• Weight. Fat tissue converts testosterone to oestrogen. Losing weight around the waist often raises levels meaningfully.
• Sleep. Most testosterone is released during sleep. Aim for seven or more hours.
• Exercise. Resistance training and regular aerobic exercise both help. In the heat, train early in the morning or in an air-conditioned gym.
• Alcohol. Heavy drinking lowers testosterone.
• Diabetes control. Better blood sugar control is linked with better hormone levels.

Supplements marketed as "testosterone boosters", including tongkat ali and similar products sold in the Philippines, are not proven to treat low testosterone or ED.

Is testosterone treatment right for me?

Testosterone replacement therapy (TRT) is a specialist decision, made only after two low morning tests and a clear pattern of symptoms. It improves desire in men with confirmed low levels, but on its own it usually does not improve erections.

The best evidence comes from the TRAVERSE trial, which enrolled men aged 45 to 80 with confirmed low testosterone and symptoms. In the sexual function part of the study, testosterone gel improved sexual activity, desire and other symptoms of low testosterone compared with placebo, but it did not improve erectile function.

So for most men with ED, TRT is not a replacement for treating blood vessel problems or for a PDE5 inhibitor. The two are sometimes used together under a doctor's care.

TRT also has real downsides, which is why an endocrinologist or urologist should be involved:

• It lowers sperm production and can cause infertility, which matters if you still want children.
• It can raise the red blood cell count, which needs regular blood tests.
• It needs monitoring of the prostate in older men.
• It is a long-term commitment, and stopping can bring symptoms back.

Never start testosterone from a gym contact or an online seller. Products sold this way may be counterfeit or contaminated, and starting without tests can hide another cause and harm your fertility.

Our sister site, Testosterone Philippines, covers low testosterone in depth: symptoms, where to get tested, what TRT involves and what it costs here.

What should you do next?

If you have ED, start with a check-up that covers blood pressure, blood sugar and cholesterol, and ask about a morning testosterone test if desire is also low. Then decide on treatment with your doctor.

For most men, the first treatment for ED remains lifestyle change and, where suitable, a prescription PDE5 inhibitor. Generic sildenafil and tadalafil cost far less than the original brands; compare checked prices on our ED medicine prices page. Your doctor decides which medicine and strength suits you. For an overview of all options, see what is erectile dysfunction, and if you are under 40, ED in your 20s and 30s.

Frequently asked questions

Does low testosterone cause erectile dysfunction?+

It can contribute, but it is not usually the main cause. Testosterone mostly drives sexual desire. Most ED comes from blood vessel problems such as high blood pressure and diabetes, though low testosterone can make PDE5 medicines work less well.

What are the symptoms of low testosterone?+

The most typical are low sexual desire, fewer morning erections, tiredness, low mood, reduced muscle and strength, and increased body fat. These symptoms have many other causes too, so a blood test is needed to confirm low testosterone.

Why does a testosterone test have to be in the morning?+

Testosterone levels are highest in the early morning and fall through the day. Guidelines recommend testing before about 10 am, and repeating a low result on a second morning, so normal daily variation is not mistaken for a problem.

Will testosterone treatment fix my erections?+

Not on its own, in most men. In the large TRAVERSE trial, testosterone gel improved desire and sexual activity in men with confirmed low testosterone, but did not improve erectile function compared with placebo.

Can I get testosterone treatment in the Philippines?+

Yes, from a doctor, usually an endocrinologist or urologist, after blood tests confirm low levels and other causes are ruled out. It is a prescription treatment with real risks, including effects on fertility, so it should never be started from a gym or online seller.