An open wound under the armpit needs careful cleaning, a moisture-friendly dressing, and extra attention to hygiene since the area is warm, damp, and constantly moving. Most minor cuts, scrapes, and small open sores in the underarm can heal well at home if you keep the wound clean and protected. Deeper wounds, wounds that won’t stop bleeding, or anything showing signs of infection need medical attention.
Clean the Wound Properly
Start by washing your hands thoroughly. Then hold the wound under clean running tap water for several minutes to flush out bacteria and debris. Wash the skin around the wound with mild soap, but keep soap out of the wound itself. If there’s visible dirt or debris, remove it with tweezers wiped down with rubbing alcohol.
Skip hydrogen peroxide and iodine. Both are commonly found in medicine cabinets, but research shows they actually slow healing. Hydrogen peroxide and povidone-iodine reduce the ability of skin cells to multiply and migrate into the wound in a dose-dependent way, meaning even small amounts interfere with repair. Hydrogen peroxide is particularly damaging to the outermost skin cells that need to regrow across the wound surface. Plain water or saline solution is the safest and most effective option for wound cleaning.
Stop the Bleeding
Minor wounds in the armpit usually stop bleeding on their own within a few minutes. If the bleeding continues, press a clean cloth or gauze pad firmly against the wound and hold it there. Raising your arm above your heart can help slow the flow. If bleeding soaks through the cloth or doesn’t stop after 10 to 15 minutes of steady pressure, the wound likely needs professional care.
Apply Ointment and Cover It
Once the wound is clean and dry, apply a thin layer of antibiotic ointment or plain petroleum jelly. This keeps the wound surface moist, which helps it heal faster and reduces scarring. Some people develop a mild rash from antibiotic ointments. If that happens, switch to petroleum jelly instead.
Cover the wound with a bandage or gauze secured with medical tape. The armpit is one of the trickiest spots to keep a bandage in place because of constant arm movement, skin-on-skin friction, and sweat. Standard adhesive bandages tend to peel off quickly here. Foam dressings are a better choice for this area because they reduce friction and shear forces on the skin, stay in place more reliably, and handle moisture well. Silicone-bordered foam dressings (sold under brands like Mepilex and ALLEVYN) are specifically designed for high-friction areas and stick without irritating surrounding skin.
Change the dressing at least once a day, or sooner if it gets wet or dirty. The armpit sweats throughout the day, and excessive moisture weakens the skin’s barrier function and raises the risk of breakdown around the wound. Each time you change the dressing, gently rinse the wound again and reapply ointment.
Avoid Deodorant and Antiperspirant
Do not apply deodorant or antiperspirant directly on or near an open wound. Antiperspirants contain aluminum compounds that are designed for intact skin, and using them on broken skin can cause irritation, stinging, rash, and even contact eczema. In clinical studies, patients with ulceration or infection in the armpit are specifically excluded from antiperspirant use because of the risk of worsening the wound. Wait until the skin has fully closed before resuming these products. In the meantime, you can apply deodorant to the opposite armpit only, or use it on clothing rather than skin.
Reduce Friction While It Heals
The underarm is a skin fold where both sides rub together constantly. This friction can reopen a healing wound or pull at new skin forming over it. Wearing a loose-fitting, soft cotton shirt helps minimize contact. If possible, avoid repetitive overhead arm movements, heavy lifting, or vigorous exercise that causes excessive sweating in the area until the wound has closed. When you do need to move your arm, a well-secured foam dressing provides a cushion between the wound and surrounding skin.
Signs of Infection to Watch For
The warm, moist environment of the armpit makes it more prone to bacterial growth than many other parts of the body. Watch for these warning signs in the days after the injury:
- Expanding redness that spreads outward from the wound edges
- Increasing pain or tenderness rather than gradual improvement
- Warmth and swelling in the surrounding skin
- Pus or foul-smelling drainage
- Fever or chills
These are signs of cellulitis, a bacterial skin infection that can spread rapidly. If the redness is expanding quickly or you develop a fever, seek medical attention right away. The skin may also develop a pitted, orange-peel texture or blisters in more advanced cases.
When It Might Not Be a Simple Wound
If you didn’t injure your armpit but developed a painful, open sore that appeared on its own, the cause may not be a standard wound. A condition called hidradenitis suppurativa causes painful lumps under the skin in areas with sweat glands, especially the armpits. These lumps can persist for weeks or months, eventually breaking open and draining pus with a noticeable odor.
Key differences from a normal wound include: the sore started as a deep, pea-sized lump rather than a surface injury; it keeps coming back in the same area or you have multiple lumps; you notice small paired blackheads nearby; or the sores leave thick, rope-like scars. Over time, tunnels can form under the skin connecting separate lumps, and these heal very slowly if at all. Hidradenitis suppurativa is a chronic condition that tends to worsen without treatment, so recurring open sores in the armpit that follow this pattern are worth bringing up with a dermatologist. This is not something that responds to standard wound care alone.
Healing Timeline
A small, clean cut or scrape in the armpit typically closes within 5 to 10 days, though the area may remain pink or sensitive for a few weeks after that. Healing takes longer in the armpit than on drier, less mobile parts of the body because of constant movement and moisture. Keeping the wound consistently covered with a clean dressing and ointment is the single most effective thing you can do to speed things along. If a wound hasn’t shown clear improvement within a week, or if it seems to be getting worse after the first two or three days, that’s a sign something else may be going on.