Blisters are fluid-filled sacs that form beneath the outer layer of skin, typically caused by friction and heat during running. Repetitive shearing forces between the foot, sock, and shoe cause the epidermis to separate from the dermis. This separation fills with a plasma-like fluid, creating the painful pocket known as a blister. Understanding the immediate and proactive steps to manage these injuries can help runners maintain their training schedule.
Immediate Care for Intact Blisters
The primary rule for managing a blister that has not yet broken is to leave the skin roof intact. This layer acts as a natural, sterile barrier against infection for the vulnerable tissue beneath it. Rupturing this barrier increases the risk of bacteria entering the wound.
Gently wash the area with mild soap and water, then pat it dry completely without bursting the blister. To reduce friction and cushion the area, apply a hydrocolloid bandage directly over the blister. These dressings absorb slight leakage and encourage natural healing.
Alternatively, specialized blister pads or moleskin can be cut into a doughnut shape and placed around the blister, leaving the center exposed. This technique elevates the surrounding area, reducing pressure directly on the fluid sac. Protecting the blister allows the underlying skin to heal, and the fluid will be reabsorbed.
Managing Blisters That Have Broken
When a blister is large, painful, or already torn, a sterile draining procedure may be necessary to relieve pressure and prevent further tearing. First, thoroughly wash your hands and the blister site with soap and water, then wipe the area with an alcohol pad or antiseptic solution. Sterilize a small needle by wiping it with an alcohol pad or heating it until red hot and allowing it to cool.
Carefully puncture the blister near its edge, making one or two small holes to allow the fluid to drain slowly. Gently press the fluid out, but avoid removing the skin flap (the blister roof), as this serves as a biological dressing. Once drained, apply a small amount of antibiotic ointment to the wound to help prevent infection.
Cover the area with a sterile, non-adherent dressing secured with medical tape or gauze. Change the dressing daily or whenever it becomes wet or dirty to keep the site clean. Monitor the area for signs of infection, such as spreading redness, increased warmth, pus, or red streaks. If these symptoms appear, seek medical attention promptly.
Strategies for Blister Prevention
Prevention focuses on managing moisture and reducing friction, the two main causes of blister formation. Proper footwear fit is foundational; ensure there is a thumb’s width of space between your longest toe and the end of the shoe. Specialized lacing techniques, such as a heel lock, can prevent the foot from sliding within the shoe, which reduces shearing forces.
Sock choice plays a significant role in moisture control. Runners should avoid cotton socks, which retain moisture like a sponge, and instead choose synthetic fabrics or merino wool. These materials effectively wick sweat away from the skin, keeping the foot drier during long efforts.
Applying friction-reducing agents directly to known “hot spots” before a run creates a temporary barrier. Specialty balms or petroleum jelly can be smoothed over areas like the heel or toes. Preventative taping using athletic tape or specialized blister patches can also be applied to these high-pressure zones for durable, localized protection.