Treatment of Large Blood Blister on Thumb
Leave the blood blister intact and cover it with a sterile dressing—do not drain or remove the blister roof, as it serves as a natural biological dressing that improves healing and reduces pain. 1
Initial Management
Keep the blister completely intact if it is not causing significant functional impairment or pain. The blister roof acts as a protective biological barrier that promotes healing and prevents infection. 1, 2, 3, 4
- Gently cleanse the area around the blister with warm water or dilute antimicrobial solution, being careful not to rupture it. 2, 3, 4
- Apply a bland emollient (such as petroleum jelly or white soft paraffin) to support the skin barrier and reduce moisture loss. 2, 3, 4
- Cover with a sterile, non-adherent dressing to protect from further trauma. 1
When Drainage May Be Considered
If the blister is very large, tense, painful, or interfering with thumb function, you may consider controlled drainage while preserving the blister roof:
- Pierce the blister at its base with a sterile needle (bevel up), selecting a site that allows gravity drainage. 2, 4
- Apply gentle pressure with sterile gauze to facilitate drainage and absorb fluid. 2, 4
- Critically important: Do NOT remove the blister roof—leave it in place as it provides optimal wound protection and pain relief. 1, 2, 3, 4
- Reapply bland emollient and a clean sterile dressing. 2, 3
Wound Care and Monitoring
- Change dressings using clean or aseptic technique to prevent secondary infection. 2, 3, 4
- Monitor daily for signs of infection including increased redness, warmth, purulent drainage, or worsening pain. 2, 3, 4
- If signs of infection develop, obtain bacterial cultures before starting topical antimicrobials. 2, 3, 4
- Apply topical antimicrobials only to areas with clinical infection—not prophylactically. 3, 4
Common Pitfalls to Avoid
- Never "deroof" or remove the blister covering—this increases infection risk and pain while delaying healing. 1, 2, 3, 4
- Avoid applying ice directly to the blister, as this can cause tissue damage. 1
- Do not use topical antibiotics prophylactically on intact blisters. 3, 4
- Avoid aggressive manipulation or repeated drainage attempts. 2, 4
Expected Course
Blood blisters typically heal spontaneously within 1-2 weeks when left intact and protected from further trauma. 5 The blood will gradually reabsorb, and the overlying skin will eventually peel away naturally once the underlying tissue has healed.