Most bumps under the armpits are caused by ingrown hairs, clogged pores, or minor skin infections, and they typically resolve with simple home care within a week or two. The right approach depends on what’s causing them, so identifying the type of bump you’re dealing with is the first step toward getting rid of it.
What’s Causing Your Armpit Bumps
The armpit is uniquely prone to bumps because it combines friction, moisture, hair removal, and product application in one small area. The most common culprits fall into a few categories.
Razor bumps and folliculitis: Shaving irritates hair follicles or allows bacteria to enter tiny nicks in the skin. This produces small red or white-tipped bumps that may itch or sting. It’s especially common in teens who are just starting to shave.
Cysts and abscesses: Deeper, more painful lumps can form when a hair follicle or sweat gland becomes blocked and infected. These feel firm or fluid-filled and can grow to the size of a marble or larger. Shaving and antiperspirant use are common triggers.
Contact dermatitis: Your deodorant or antiperspirant may be causing a bumpy, itchy rash. Fragrance is the most common allergen, present in about 90% of deodorants and antiperspirants. Propylene glycol, found in nearly half of these products, is the second most frequent irritant.
Swollen lymph nodes: Lymph nodes sit just beneath the skin in the armpit and can swell in response to infections elsewhere in the body, from a minor arm infection to something systemic like mono. These feel like smooth, movable lumps and usually shrink on their own once the underlying infection clears.
Hidradenitis suppurativa (HS): If you get recurring painful bumps in the same area that leave scars or connect under the skin through tunnels, you may have HS, a chronic inflammatory condition. Early-stage HS involves single or multiple abscesses without scarring. More advanced stages produce interconnected tunnels beneath the skin with significant scarring.
Home Treatments That Work
For most armpit bumps caused by shaving irritation, minor folliculitis, or small cysts, you can treat them at home without seeing a doctor.
Warm compresses are the simplest and most effective first step. Soak a clean washcloth in warm water, wring it out, and hold it against the bump for 10 to 15 minutes several times a day. This increases blood flow, draws infection closer to the surface, and helps abscesses drain naturally. Never squeeze or pop an armpit bump yourself, as this can push bacteria deeper into the tissue.
A benzoyl peroxide body wash at 10% concentration can clear bacterial folliculitis. Apply it to the affected area, let it sit for 5 to 10 minutes, then rinse. Use it daily until the bumps resolve. Keep in mind that benzoyl peroxide bleaches fabric, so use white towels.
If you suspect your deodorant is the problem, stop using it for a week and see if the bumps improve. Switch to a fragrance-free, propylene glycol-free formula. “Natural” or “sensitive skin” labels don’t guarantee the product is free of common allergens, so check the ingredient list yourself.
When You Need Medical Treatment
Some armpit bumps won’t respond to home care. A bump that keeps growing after a few days, becomes intensely painful, develops a fever alongside it, or produces foul-smelling drainage needs professional attention. The same goes for bumps that keep coming back in the same spot.
For bacterial infections, doctors typically prescribe topical antibiotics like clindamycin gel or mupirocin ointment, applied twice daily. These work well for surface-level folliculitis that hasn’t responded to over-the-counter treatments. Deeper infections may require oral antibiotics.
Large abscesses often need incision and drainage, a straightforward procedure where a doctor opens the abscess and removes the pus. You can usually go home the same day. The wound is left open intentionally so it heals from the inside out, and your doctor may pack it with antiseptic dressing to keep it draining. Healing can be slow when packing is involved, and you’ll need to keep the area clean while it closes.
Hidradenitis suppurativa requires ongoing management with a dermatologist. Treatment varies by severity but can include prescription anti-inflammatory medications, antibiotics, or procedures to open and drain recurring lesions.
How to Prevent Armpit Bumps
Most armpit bumps are preventable with a few habit changes, particularly around shaving.
- Shave with the grain. Always shave in the direction your hair grows, not against it. Going against the grain gives a closer shave but dramatically increases the risk of ingrown hairs.
- Replace your razor often. Swap out a disposable razor after 5 to 7 shaves. Dull blades require more pressure and passes, which irritates the skin. Store your razor in a dry place between uses so bacteria don’t build up on the blades.
- Shave after warming the skin. Shave at the end of a shower when the hair is soft and the pores are open. Use a shaving gel or cream rather than going dry.
- Wear breathable fabrics. Tight synthetic clothing traps sweat and friction against the armpit. Loose, moisture-wicking fabrics reduce both irritation and bacterial growth.
- Apply deodorant to clean, dry skin. Putting product on damp or freshly shaved skin increases the chance of irritation and clogged pores. Wait a few minutes after shaving before applying anything.
If you’re prone to recurring bumps, consider alternatives to shaving. Electric trimmers cut hair just above the skin’s surface without creating the sharp-tipped stubble that causes ingrown hairs. Laser hair removal is a longer-term option that reduces hair growth and is sometimes recommended for people with hidradenitis suppurativa.
Bumps That Need Prompt Evaluation
Most armpit lumps are harmless, but certain characteristics suggest something more serious. A lump that is hard and immovable, painless, growing steadily over weeks, or appearing on only one side without an obvious cause (like a recent infection or vaccination) warrants a medical evaluation. Normal lymph nodes are oval, smaller than 2 centimeters, and feel somewhat movable under the skin. Nodes that become round, firm, and fixed in place have features that doctors take more seriously.
Certain vaccinations and infections can also cause temporary lymph node swelling in the armpit. If you recently had a vaccine in that arm or have been fighting an infection, a swollen node is likely a normal immune response and should shrink within a few weeks. A lump that persists beyond that timeframe, or one that appears without any clear trigger, is worth having checked.