Blisters Explained
In brief: Blisters are small pockets of fluid that form in the upper layers of skin in response to friction, heat and moisture. In runners they appear where the foot rubs against the shoe or sock, commonly on the heels, toes and balls of the feet. They are usually minor but can be painful and disruptive. Well-fitting shoes, moisture-wicking socks, lubricant and keeping the feet dry are the main ways to prevent them.
What are blisters?
A blister is a fluid-filled bubble that forms in the upper layers of the skin when those layers are repeatedly rubbed and separate, with fluid filling the gap to cushion the area. In runners they are a friction injury, made worse by heat and moisture. They most often appear on the heels, the tips and sides of the toes, and the balls of the feet.
What causes them in runners?
The core cause is friction, the foot or sock rubbing repeatedly against the shoe, magnified by sweat and damp socks that soften the skin. Shoes that are too tight, too loose or not broken in, seams and rough spots, and long distances all increase the rubbing. Heat builds up over a run and makes the skin more vulnerable.
Symptoms to recognise
A developing blister often starts as a hot spot, a warm, sore patch of skin, before the fluid-filled bubble appears. The blister itself is usually a raised pocket of clear fluid that is tender to pressure. Occasionally a blister fills with blood, or becomes red and painful if irritated or infected.
Treatment and recovery
Small, intact blisters are usually best left unburst and protected with a dressing or blister plaster, as the skin acts as a natural barrier against infection. If a large blister is very painful it may need draining with proper hygiene, ideally by following first-aid guidance, while leaving the roof of skin in place. Keep the area clean and watch for signs of infection such as spreading redness or pus, which need medical attention. Most blisters heal within a week or so.
Blisters and your running kit at OD's
Well-fitting shoes that are not too tight or too loose, paired with moisture-wicking running socks, are the foundation of blister prevention, reducing both friction and dampness. At OD's Designer Clothing we stock premium running footwear from On, Saucony and Salomon, with fitting help in St Helens. We offer next-day delivery and free click and collect.
Please note: This guide is general information for runners, not medical advice. If you have pain that is severe, persistent or getting worse, see a GP, physiotherapist or qualified sports clinician for diagnosis and treatment.