The relationship between testosterone and erectile dysfunction is real but often misunderstood. Low testosterone is not the most common cause of ED — vascular and psychological factors are more prevalent — but it is an important and often overlooked contributor, particularly in men over 40 who also report reduced libido, energy, and mood changes alongside erection difficulties.
How Testosterone Affects Erectile Function
Testosterone plays several roles in the erectile response:
- Libido: Testosterone is the primary driver of sexual desire. Without adequate libido, the psychological and neurological signals that initiate erection are diminished.
- Nitric oxide synthesis: Testosterone supports the production of nitric oxide in penile tissue, which is the chemical signal that triggers arterial dilation and blood flow during erection.
- Smooth muscle function: Testosterone maintains the health of penile smooth muscle tissue. Testosterone deficiency can lead to structural changes that impair vascular response.
- PDE5 regulation: Testosterone influences the activity of phosphodiesterase enzymes that regulate the erectile response — the same pathway targeted by ED medications.
Signs That Low Testosterone May Be Contributing to Your ED
ED alone is not necessarily a sign of low testosterone. The following combination of symptoms suggests hormonal evaluation is warranted:
- Erectile dysfunction alongside significantly reduced interest in sex (not just erection difficulty)
- Fatigue that is disproportionate to activity level and sleep quality
- Loss of morning erections over a period of months
- Changes in body composition (increased fat, reduced muscle) without significant changes in diet or exercise
- Mood changes including depression, irritability, or difficulty concentrating
- Reduced body hair or changes in testicular size
Diagnosing Low Testosterone
Low testosterone requires blood testing — it cannot be reliably diagnosed by symptoms alone. Testing should include:
- Total testosterone — two morning draws to confirm consistently low levels
- Free testosterone — the bioavailable fraction, which can be low even with normal total T
- LH and FSH — to determine whether the cause is testicular (primary) or pituitary (secondary)
- SHBG — elevated SHBG reduces bioavailable testosterone regardless of total level
Treatment Options: ED Medications vs. TRT vs. Both
| Approach | Addresses | Best For |
|---|---|---|
| PDE5 Inhibitors (sildenafil, tadalafil) | Vascular component of erection | ED with normal testosterone and libido |
| Testosterone Replacement Therapy (TRT) | Hormonal deficiency, libido, energy | Men with confirmed low testosterone and libido loss |
| TRT + PDE5 Inhibitor | Both vascular and hormonal components | Men with both low T and significant vascular ED |
Research shows that in men with confirmed low testosterone and ED, TRT alone improves both libido and erection quality in a significant proportion. However, men with both hormonal and vascular ED often benefit from both treatments.
Why Some Men Do Not Respond Well to ED Medications
If PDE5 inhibitors (sildenafil, tadalafil) are producing limited results, underlying low testosterone should be evaluated. Research shows that testosterone deficiency can blunt the response to ED medications — and that restoring testosterone levels can significantly improve their effectiveness.
Frequently Asked Questions
If I have ED, should I automatically get my testosterone tested?
If your ED is accompanied by reduced libido, fatigue, or mood changes, yes — testosterone testing is warranted. ED in isolation with normal libido is more likely vascular or psychological in origin, and ED medications are typically the first-line approach.
Will TRT alone fix my ED?
In men with primarily hormonal ED (low testosterone with reduced libido), TRT often substantially improves both libido and erection quality. In men with significant vascular ED on top of low testosterone, a combination approach is usually more effective.
Can I get both TRT and ED medications through telehealth?
Yes. Many telehealth platforms specialize in men's health and can manage both prescriptions, though some may require separate program enrollment for each treatment category.
Find a Provider That Evaluates the Full Picture
The best ED care platforms screen for hormonal and vascular factors rather than simply prescribing. Our comparison highlights providers with comprehensive intake and lab requirements.
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