ED: The Basics — Erectile Dysfunction Explained

Erectile dysfunction (ED) is one of the most common men’s health concerns in the UK, affecting an estimated one in five men at some point in their lives. Despite its prevalence, many men feel reluctant to seek help — but effective, MHRA-approved treatments are available, and there is no need to suffer in silence. This guide covers the basics of erectile dysfunction, including how erections work, what causes ED, and the main treatment options including Viagra and Cialis.

How Does an Erection Work?

For an erection to occur, a specific sequence of events must happen in the right order. When a man is sexually stimulated (physically or psychologically), nerves in the penis release nitric oxide, which causes smooth muscle in the penile arteries to relax. This relaxation allows blood to flow into the two spongy chambers of the penis (the corpus cavernosum), which expand and create the firm erection. When sexual stimulation stops, or after orgasm, the process reverses.

Erectile dysfunction occurs when this process is disrupted at any point — whether due to insufficient blood flow, nerve damage, hormonal imbalance, or psychological factors.

Main Treatment Options for ED

All four medications are PDE5 inhibitors — they work by the same mechanism (increasing blood flow to the penis) but differ in how quickly they work and how long the effect lasts. For a detailed comparison, see our guide to Viagra vs Cialis vs Levitra vs Stendra.

Dosage and Safe Use

• Sildenafil (Viagra) is available in 25mg, 50mg, and 100mg tablets. The standard starting dose is 50mg taken 1 hour before sexual activity
• Take on an empty stomach or after a light meal for best results — a large, high-fat meal delays absorption
• Never take more than one tablet per day
• Avoid combining with nitrate medicines (used for chest pain) — this combination can cause a dangerous drop in blood pressure
• Avoid grapefruit juice, which can affect how the drug is metabolised

When to See a Doctor About ED

See a doctor if ED has been present for more than a few weeks, is causing significant distress, or if you have any underlying health conditions (heart disease, diabetes, hypertension) that may be contributing. ED can sometimes be an early warning sign of cardiovascular disease. For a detailed look at physical and psychological causes, see our guide to what causes erectile dysfunction.