What actually counts as ED
The clinical definition is the persistent or recurrent inability to attain or maintain an erection sufficient for satisfactory sexual performance. Two words carry the weight: persistent and satisfactory.
- One bad night after too much alcohol, too little sleep or too much stress is not erectile dysfunction. It is being human.
- Most clinicians use a threshold of difficulty on the majority of attempts, over roughly three months.
- It is also defined by what bothers you. A pattern that neither you nor your partner finds a problem does not need treatment.
Assessing yourself before you go
The most widely used screening tool is the Sexual Health Inventory for Men (SHIM), also known as the IIEF-5 — five questions about the last six months, scored 5 to 25.
| Score | Interpretation |
|---|---|
| 22–25 | No erectile dysfunction |
| 17–21 | Mild |
| 12–16 | Mild to moderate |
| 8–11 | Moderate |
| 5–7 | Severe |
The questions that matter most
The history is where the diagnosis is actually made. These are the questions a good clinician will ask, and they are worth thinking about beforehand.
- Did it start suddenly or gradually?
- Sudden onset, especially traceable to an event, points towards psychological causes. Gradual decline over months to years points towards vascular causes.
- Do you get erections on waking or when alone?
- Perhaps the single most useful question. If yes, the physical machinery works — which points towards psychological or relational factors.
- Is it the getting or the keeping?
- Difficulty maintaining an erection that starts well can suggest venous leak or anxiety; difficulty achieving one at all more often suggests arterial or neurological causes.
- Is it every time, or situational?
- Variation by partner, setting or mood strongly suggests a psychological component.
- What has changed?
- New medication, new diagnosis, weight change, new stress, relationship change. Timing is diagnostic.
- What about desire and ejaculation?
- Low desire points towards testosterone, mood or medication. Painful or absent ejaculation raises different questions again.
Examination and tests
Physical examination
- Blood pressure and pulse, plus a check of peripheral pulses.
- Waist circumference and BMI.
- Genital examination — testicular size and consistency, and palpation of the penile shaft for Peyronie's plaque.
- Assessment of secondary sexual characteristics and any breast tissue development.
- A prostate examination where symptoms or age make it relevant.
Blood tests worth having
| Test | Why |
|---|---|
| HbA1c or fasting glucose | Screens for diabetes and prediabetes — a leading cause |
| Fasting lipid profile | Cardiovascular risk assessment |
| Morning total testosterone | Especially if libido is reduced. Needs a second confirmatory test if low |
| Full blood count | Anaemia and, if testosterone is being considered, baseline haematocrit |
| Thyroid function | Both over- and underactive thyroid can affect sexual function |
| PSA | Where age and symptoms make prostate assessment appropriate — a shared decision |
Specialised tests
These are not routine. They belong to specific situations, usually in a urology clinic:
- Penile duplex Doppler ultrasound — measures blood flow after an injected vasodilator. Used when arterial disease or venous leak is suspected, or before reconstructive surgery.
- Nocturnal penile tumescence testing — measures erections during sleep. Rarely used now, occasionally relevant in medico-legal contexts.
- LH, FSH and prolactin — where testosterone is confirmed low, to find out why.
FAQ
Frequently asked questions
How do I know if I have ED or just an off night?
The clinical threshold is difficulty on most attempts over roughly three months. Occasional difficulty is normal and extremely common.
Do I need tests, or can I just get a prescription?
You can get a prescription without tests, and many telehealth services work that way. But ED is a recognised early warning sign of cardiovascular disease and diabetes, so skipping the workup means potentially missing something more important than the symptom.
What does it mean if I still get morning erections?
It suggests the nerves, hormones and blood vessels are working, which points towards psychological or relational factors as the main driver.
Should I see a GP or a urologist first?
A primary care clinician is the right starting point for most men — they can assess cardiovascular risk and initiate treatment. See a urologist if tablets fail, if there is curvature or pain, or after prostate surgery.
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]Mayo Clinic. Erectile dysfunction — symptoms and causes.
- [04]Urology Care Foundation. What is Erectile Dysfunction?.