Two pathways, two prognoses
Understanding which nerve route is damaged explains almost everything about what will and will not work.
- Psychogenic erections
- Triggered by sight, thought, memory or arousal in the brain. The signal descends the spinal cord and exits around T11–L2. These are the erections that respond to attraction and imagination.
- Reflexogenic erections
- Triggered by direct physical stimulation of the genitals. The signal travels to the sacral cord (S2–S4) and back out again without needing the brain. This is a spinal reflex arc.
- Nocturnal erections
- Occur during REM sleep, driven centrally. Their loss is often the first thing men notice — see morning erections explained.
The conditions involved
| Condition | What happens | Treatment notes |
|---|---|---|
| Multiple sclerosis | Demyelination interrupts signal transmission. Sexual dysfunction is very common and can be an early feature. Fatigue, spasticity and bladder symptoms compound it. | PDE5 inhibitors are often effective. Address fatigue, spasticity and mood in parallel. |
| Spinal cord injury | Effect depends entirely on level and completeness. Reflexogenic erections often survive upper-motor-neuron injuries. | PDE5 inhibitors work well in many cases. Injections and vacuum devices are established alternatives. Beware autonomic dysreflexia in high injuries. |
| Parkinson's disease | Autonomic dysfunction plus reduced dopaminergic drive. Mobility, tremor and mood all contribute. | PDE5 inhibitors are commonly used. Watch for postural hypotension. Some dopamine agonists can paradoxically cause hypersexuality — report changes in urges. |
| Stroke | Depends on the area affected; often compounded by mobility, mood, fear of recurrence and antihypertensive medication. | Treat cardiovascular risk factors. Review blood pressure medication choice. Sex is usually safe once stable — ask for a specific clearance. |
| Diabetic neuropathy | Small-fibre autonomic nerve damage. One of the most common neurological contributors overall. | See diabetes and ED. Response to tablets is lower; injections work well. |
| Pelvic surgery or trauma | Direct injury to the cavernous nerves — most commonly after prostate surgery, but also after rectal surgery or pelvic fracture. | See ED after prostate treatment. |
| Epilepsy | Both the condition and some antiepileptic drugs affect sexual function and hormone levels. | Do not stop antiepileptics. Ask about drug choice and check testosterone. |
What tends to work
- PDE5 inhibitors first, in most cases. They are frequently effective in MS and spinal cord injury, and higher doses are often needed. Give them a proper trial.
- Injection therapy where tablets fail. Because it acts directly on the erectile tissue it does not need an intact nerve signal, which makes it the most reliable option in significant neuropathy.
- Vacuum devices, which work mechanically and require no nerve or arterial function at all.
- Review the medication list. Antispasmodics, antidepressants, antiepileptics and antihypertensives are all common in this group and all affect sexual function. See medications that cause ED.
- Address sensation and positioning with a specialist. Reduced sensation, spasticity and mobility limitations all have practical workarounds that clinicians rarely raise unprompted.
FAQ
Frequently asked questions
Can ED be the first sign of a neurological condition?
It can. Sexual dysfunction is sometimes an early feature of multiple sclerosis and other conditions. ED appearing alongside any new neurological symptom — numbness, weakness, visual change, bladder problems — should be assessed promptly.
Do ED tablets work after a spinal cord injury?
Often yes, and sometimes very well, particularly where the sacral reflex arc is intact. Higher doses are frequently needed and the response depends on the level and completeness of the injury.
Why do injections work when tablets do not?
Tablets amplify a nerve signal. Injections act directly on the smooth muscle of the erectile tissue, so they work whether or not the signal arrives.
Is sex safe after a stroke?
For most people with stable disease, yes. Ask your clinician for a specific assessment, and review whether your blood pressure medication is contributing to the problem.
Sources
What this is based on
We link to primary sources — clinical guidelines, regulator publications and peer-reviewed research — wherever possible. Links open on third-party sites we do not control.
- [01]American Urological Association. Erectile Dysfunction: AUA Guideline (2018).
- [02]National Institute of Diabetes and Digestive and Kidney Diseases. Definition & Facts for Erectile Dysfunction.
- [03]Urology Care Foundation. What is Erectile Dysfunction?.
- [04]Mayo Clinic. Erectile dysfunction — symptoms and causes.