Erectile Dysfunction
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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’s 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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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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