Erectile dysfunction is the inability to achieve or maintain an erection sufficient for satisfactory sexual performance. It affects up to 50% of men between 40 and 70.

Erection requires an intact parasympathetic reflex at S2 and S3.
Ejaculation requires an intact sympathetic L1 root.
Mnemonic: Erection & ejaculation = Point & Shoot (Para & Sym)


Organic causes

  • Spinal cord or cauda equine disease
  • Multiple sclerosis
  • Endocrine disease
    • DM
    • Hypogonadism
    • Hyperprolactinaemia
  • Generalised vascular disease
  • Trauma causing nerve or vascular disease
    • E.g. after surgery for prostate ca
  • Hypertension
  • Drugs
  • Androgen deficiency is a¬†very rare¬†cause – typically affecting middle aged men

Psychological causes

  • Depression
  • Relationship problems
  • Sexual orientation uncertainties
  • Primary psychogenic erectile dysfucntion
    • Accounts for about 20% of cases
    • Typically young men at the begging of their sexual experience

Age-related problems (>50) tend to follow a common vicious circle:



  • ED occurs in 52% of men aged 40-70:
    • 17% have occasional ED
    • 25% have moderate ED
    • 10% have complete ED


  • Sexual history
  • Smoking history
  • Hx of hypertension
  • Hx of diabetes
  • Hx of cardiovascular disease
  • Hx of prostate disease or cancer
  • Medications
  • Ilici drug use
  • Depression


All patients should have a random plasma glucose or urinalysis for glucose to exclude diabetes. Further tests to consider include:

  • FBC
  • LFTs
  • Fasting lipid profile
    • Assessing for cardiovascular disease risk factors
  • Fasting glucose (or HbA1c)
  • U+Es (for renal function)
  • Leutenising Hormone in the most useful hormonal test
    • Testosterone, prolactin and hormone binding globulin may be considered as second line investigations
  • TFTs



Some general principles include:

  • Smoking cessation
  • Ensure underlying disorders are well controlled
    • Hypertension
    • Diabetes
    • Cardiovascular disease
    • Treating these is unlikely to reverse the course of erectile dysfunction alone but may prevent it from deteriorating further


Pharmaceutical treatments

Before starting pharmacotherapy – ensure sufficient cardiovascular fitness to engage in sexual activity.

First line

  • Phosphodiesterase-5 inhibitors eg. Sildenafil citrate (Viagra), tadalafil, verdenafil
  • +/- counselling as appropriate
  • Ensure not taking nitrites (contra-indicated – may cause FATAL¬†hypotension¬†go straight to second line agents)
  • e.g.¬†Sildenafil 50mg orally – one hour before intercourse
  • e.g.¬†Tadalafil 10mg orally – PRN – effects may be present up to 24 hours after dose
  • Both are maximum of one dose per 24 hours
  • Sildenafil comes in 100mg tablets – it may be cost effective for patients to be prescribed this dose and then use half or even a quarter of a tablet PRN
  • These agents¬†do NOT cause erection without sexual arousal
  • Possible side effects include:¬†dizziness, headache, facial flushing, nasal congestion,¬†disturbance in colour vision
  • Side effects are dose related

Second line

  • Intracavernosal injections of¬†alprostadil
  • Carry a risk of priapism and patients must be educated about how to manage this – including keeping pseudoephedrine at home in case of emergency use
  • Other risks include – haemorrhage and bruising, cavernosal fibrosis and localised pain
  • Teach patients to inject themselves
  • Start with a low dose and titrate to effect – e.g. 2.5 mcg (Max dose 60 mcg)
  • Give the lowest dose that achieves erection within 60 minutes
  • Duration is dose dependent
  • Vacuum erection device – may also be considered

Third line

  • Intracavernosal combination –¬†alprostadil, papaverine, phentolamine

Fourth line

  • Surgery – penile implant
  • If severe cardiovascular disease of the pudendal arteries exists then management of this may also be appropriate (e.g. with bypass graft – similar to CABG)

Other experimental treatments – such as shockwave therapy – are unproven (and likely ineffective – and expensive!)

Anxiety-induced ED (primary psychogenic erectile dysfunction) is treated using a therapeutic regimen based:

  • Sexual history
  • A period of abstention for several weeks
  • Onset of therapy


  • Murtagh‚Äôs General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
  • Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
  • Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy

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