Why Does Pus Come Out When I Squeeze My Armpit?

Reviewed on 11/18/2022
Woman feeling a lump in her armpit
An armpit lump such as an abscess or cyst, or hidradenitis suppurativa are usually the causes of pus coming from the armpit.

Pus may come out when you squeeze your armpit if lumps (cysts or abscesses) under the skin are present. Pus coming from the armpit may also be caused by hidradenitis suppurativa (also called HS or acne inversa), a progressive and chronic skin condition that causes painful, swollen, red bumps to form on the body, often in skin folds or places where skin rubs together such as the armpits. 

Causes of cysts or abscesses under the skin in the armpit may include: 

  • Shaving 
  • Use of antiperspirants (not deodorants)

Most of the time, the cause of hidradenitis suppurativa is unknown but it is believed to be a result of both genetic and environmental factors. The condition tends to run in families. It is not contagious and it is not caused by poor hygiene. 

The bumps start with a blockage of hair follicles in body parts with a high concentration of sweat glands (apocrine glands), such as the armpits or groin. These blocked hair follicles trap bacteria, which causes pain, inflammation, redness, and eventually, rupture. The reason for this blockage is not known. 

When to See a Doctor

See a doctor if you have a lump in your armpit with pus coming out and the lump: 

  • Is accompanied by redness, pain, or fever 
  • Is very firm 
  • Does not go away
  • Gets bigger
  • You are female (may be a sign of breast cancer)
    • It is not possible to diagnose cancer by touch or sight alone

If you have a lump in your armpit or pus coming out of your armpit when you squeeze and are at all concerned, talk to your doctor. 

What Are Symptoms of Pus Coming from the Armpit?

Symptoms of cysts or abscesses in the armpit may include: 

  • Swelling under the skin
  • Pain and tenderness in the armpit
  • Warmth and redness in the armpit
  • A visible build-up of white or yellow pus under the skin in the armpit
  • Fever 
  • Chills

The main symptom of hidradenitis suppurativa include is painful, swollen, red bumps that may drain pus or blood. 

  • The bumps may:
    • Become infected
    • Have a foul odor
    • Last a long time and worsen over time
  • Skin may harden and form scars around the bumps
  • Several bumps may form in one area and cause a small “tunnel” in the skin called a sinus tract
  • In addition to the armpits, common locations for the bumps are places where skin rubs together, including:
    • Groin
    • Inner thighs
    • Buttocks
    • Around or near the anus
    • Under the breasts


Acne is the result of an allergy. See Answer

How Is Pus Coming from the Armpit Diagnosed?

The cause of a pus coming from the armpit is diagnosed with a patient history and physical examination of the area. Depending on the suspected cause of the pus in the armpit, tests may include: 

  • Blood tests
  • Complete blood cell count with differential and platelet counts (occasionally elevated white blood count)
  • Erythrocyte sedimentation rate (ESR)
  • C-reactive protein assay
  • Urinalysis
  • Serum multiphasic analysis with determination of the serum iron level and serum protein electrophoresis 
  • Bacteriologic analysis, usually with a culture swab
  • Immunochemistry for various cytokeratins and 6 desmosomal cadherins
  • Histologic examination
  • Ultrasound of hair follicles and skin thickness may help reveal abnormalities deep within the follicle.
  • Fluid culture from the lump to check for infection
  • Tissue biopsy

Three criteria need to be met for a diagnosis of hidradenitis suppurativa, including:

1.) The lesions are typical:

  • They are painful, red, and papules smaller than 1 cm in diameter or nodules larger than 1 cm in diameter
  • Abscesses are painful and tender, and there is discharge from the papules or nodules
  • Scarring (dermal contracture)
  • Double-ended acne papules (comedones)

2.) Lesions have a characteristic distribution

3.) Lesions are recurrent (at least two recurrences over a period of six months)

What Is the Treatment for Pus Coming from the Armpit?

Treatment for a lump in the armpit depends on the cause. Often, lumps are benign and don’t need treatment. 

Treatment for a cyst or abscess the armpit that is infected may include: 

  • Warm compresses
  • Antibiotics if infected
  • Draining or lancing the cyst or abscess

In the early stages, treatment for hidradenitis suppurativa may include conservative measures and lifestyle modifications, such as:

  • Shower daily and gently wash areas of HS with hands 
  • Weight loss if overweight or obese
  • Don’t smoke
  • Use ordinary soaps and antiseptic and antiperspirant agents (e.g., 6.25% aluminum chloride hexahydrate in absolute ethanol)
  • Apply warm compresses with sodium chloride solution or Burow’s solution
  • Wear loose-fitting clothing on areas where HS is present 
  • Laser hair removal

Medications that are used to treat hidradenitis suppurativa include:

  • Antibiotics
  • Retinoids
  • Corticosteroids 
  • Antiandrogens
  • Immunosuppressants 
  • Estrogen derivatives 
  • 5-Alpha-reductase inhibitors 

Surgery may be indicated once abscesses, fistulas, scars, and sinus tracts have formed. Non-ablative radiofrequency therapy may be used for patients in certain stages of the disease. 

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Reviewed on 11/18/2022

Image source: iStock Images