What is the best treatment for a large water blister on the plantar surface of the foot behind the hallux in a 15-year-old athlete?

Management of Large Plantar Blister in a 15-Year-Old Athlete

For a large water blister on the plantar surface behind the big toe in this athlete, drain the blister aseptically with a sterile needle while preserving the blister roof, then apply a protective low-adhesion dressing to allow continued activity with minimal discomfort. 1, 2, 3

Immediate Treatment Approach

Drainage Technique

• Perform aseptic drainage for large blisters rather than leaving them intact, as larger blisters respond better to therapeutic drainage compared to conservative management 2, 3
• Pierce the blister with a sterile needle to release fluid while leaving the blister roof completely in place - this protects the underlying tissue and reduces infection risk 4, 1
• The blister roof serves as a biological dressing that prevents secondary bacterial infection and promotes faster healing 1, 3

Post-Drainage Care

• Cover the drained blister with a low-adhesion dressing such as Mepitel or Atrauman to protect the area while allowing continued athletic activity 4
• Hydrocolloid dressings provide excellent pain relief and may allow the athlete to continue physical activity if necessary 3
• Avoid high-adhesion dressings that could remove the protective blister roof when changed 4

Key Clinical Considerations

When NOT to Drain

• Do not drain small blisters - these are self-limited and respond well to conservative treatment with protective padding alone 2
• Leave blisters intact if they are in areas where drainage would be difficult to keep clean 1

Infection Prevention

• The primary complication risk is secondary infection from either spontaneous rupture or therapeutic drainage 2
• Monitor for signs of infection including increased erythema, warmth, purulent drainage, or systemic symptoms 4
• No evidence supports routine antibiotic use for uncomplicated friction blisters 3

Prevention for Future Activity

Footwear Modifications

• Ensure properly fitted athletic shoes that are broken in gradually before intense activity 1, 5
• Consider closed-cell neoprene insoles, which have evidence for reducing foot blister incidence 3
• Use double-layer sock systems (thin polyester inner sock with thick wool or polypropylene outer sock) - this combination significantly reduces blister incidence in active populations 3, 6

Skin Protection Strategies

• Apply protective padding over blister-prone areas before activity 1
• Use drying foot powders and non-slip insoles, though evidence for their effectiveness is limited 1, 3
• Acrylic fiber socks result in fewer foot blisters compared to other materials in runners 3

Biomechanical Assessment

• Evaluate for underlying foot biomechanical defects that may predispose to recurrent blistering in this location 1
• The plantar surface behind the hallux suggests possible excessive pressure or shear forces during push-off phase of gait 6

Return to Activity

• The athlete can typically return to activity immediately after drainage and appropriate dressing application 2, 3
• Hydrocolloid dressings specifically allow continued physical activity with reduced pain 3
• Monitor the site daily for signs of infection or dressing failure 5

Common Pitfalls to Avoid

• Never remove the blister roof - this increases pain, infection risk, and healing time 1, 3
• Avoid overdebridement of surrounding callused tissue, which can make underlying skin more susceptible to further blistering 4
• Don't assume antiperspirants or simple drying powders alone will prevent recurrence - evidence does not support their effectiveness 3
• Ensure the athlete wears sandals in communal shower areas to prevent secondary fungal infections that commonly affect athletes' feet 5