Pain in Underarm (Armpit)

Armpit pain can result from injuries, muscle strain, allergy, infections and skin rashes due to excessive sweating. Some reasons for this pain can also be pinched nerves, cysts, autoimmune disorders or even cancer.

There is no known way that both right and left armpit would experience pain exclusively. Menstrual periods or infections like infectious mononucleosis can cause pain in both armpits.

Underarm pain

Strained Muscles and Various Other Injuries

A sudden pain can experience on the armpit resulting from the excessive use or muscle strain on the arm. Mild swelling and tenderness can also observe in the armpit muscles.

Also, Armpit pain can also result from overuse of crutches, direct injury to the armpit, fracture or injury the ribs, dislocation of the shoulder, surgery in the area, or even wearing splints.

A stabbing pain can experience on the chest side, the inner aspect of the arm, and the shoulder due to the overuse of serratus anterior muscle.

Pain under the collarbone, upper back, and armpit can experience due to pectoralis minor syndrome.

Pressure on the nerves (brachial plexus) located close to armpit near the neck muscles, cervical rib (eventual abnormal rib), and clavicle can experience pain, numbness or tingling sensation in the neck, shoulder, armpit as well as on the inner side of the arm (thoracic outlet syndrome). This condition can result from the overuse of arm during extensive work or even due to the wrong posture while sitting for students such as bending onward by elbow support.

Lack of sensation and mild pain can experience under the armpit and winged scapula (projecting scapula) due to long thoracic nerve injury on the chest just below the armpit.

Constant pain in the armpit can also result in people with hyperhidrosis (heavy sweating) if they are getting treated with Botox injections.

A fracture in the rib can also result in instant, severe pain in the chest just under the armpit.

Agonizing Lumps: Inflamed Lymph Nodes

Lymph nodes are easily felt among the skinny people as they can feel non-tender, soft and tiny nodules compared to people with the healthy body. When the lymph nodes grow bigger than 1cm, it diagnosed as lymphadenopathy.

General Infections Resulting in Agonizing Lumps in Both The Armpits

When the lymph nodes in the armpit are infected, they are visibly hard, gentle, and large, and often feel swollen on the skin.

Once infected by the infectious mononucleosis such as Epstein-Barr virus, the patient can suffer from high fever, sore throat, weakness, heavy sweating, and expanded as well as agonizing lymph nodes in the armpits and neck, mostly on two sides. This type of infection mainly found in children and young adults.

Accidental consumption of cat feces can result in contraction of parasitic infection, Toxoplasmosis and could lead to expanded lymph nodes in the armpit and neck, mild fever, and sore throat.

Bacterial infections such as rat-bite fever and bubonic plague can also cause instant fever and profoundly tender lymph nodes occurring in the armpits.

Bites and Local Infections

Lymphatic vessels (lymphangitis) can infect due to a venomous bite or an infection caused by bacteria contracted by the hands, fingers, or arm leading to slight red linings towards the armpit lymph nodes.

  • Bacterial infections:
    • You can infect by cat scratch disease resulting from literally a cat bite, lick, or scratch.
    • You can suffer from Tularemia (deer-fly fever, rabbit fever) due to the transmission of bacteria via tick bite or deer fly.
    • Boils, cellulitis, and impetigo can result from streptococcal (strep) or staphylococcal (staph) skin infections.
    • Armpit abscess occurs when a massive compilation of pus compiled below the skin as a result of hidradenitis suppurative, furuncle, surgery or injury. The warm, gentle, tiny or sometimes golf ball-sized, the rubbery lump can also lead to throbbing pain.
    • Instant agonizing inflammation of the lymph nodes in the armpit can also stem from a spider, scorpion, or snake bite.

Trouble-free Rigid Armpit Lumps

Sebaceous cyst, specifically a blocked sebaceous gland, looks like a tiny marble-sized piece that secretes white pus when squeezed.

A benign tumor containing fat tissue is called Lipoma.

Typically found in women diagnosed with diabetes type 1, Diabetic mastopathy is a condition with hard painless lumps in, either both or one breast or armpit.

These oversized, hard but trouble-free lymph nodes in the armpit can also occur in cases of some bacterial (tuberculosis, syphilis, brucellosis), fungal (sporotrichosis, histoplasmosis),  and viral infections (measles, finger herpes, shingles, HIV/AIDS).

Children, within the age group of 6 months to 12 years, can also have oversized but trouble-free armpit or groin area lymph nodes, in addition to skin rashes on the arms, face, and legs that are consistent several months resulting from an infection condition called Infantile favorite acrodermatitis or Gianotti-Crosti syndrome.

  • Vaccines against hepatitis B, measles-mumps-rubella, influenza, smallpox, polio, diphtheria, and pertussis
  • Bacterial Infections: Lyme disease, cat scratch disease
  • Viral Infections: Hepatitis A, B, or C, infectious mononucleosis, rubella, cytomegalovirus (CMV), herpes virus, parvovirus B19

You can also witness oversized yet painless (may be painful in some cases) chest, neck, groin, and armpits lymph nodes, in addition to the skin rash and joint pain resulting from systemic lupus erythematosus (SLE), rheumatoid arthritis, sarcoidosis, Sjögren’s syndrome, and several other autoimmune diseases.


Cancer can also cause numerous, oversized, permanent, hard, and hard armpit lymph nodes.

Here are some symptoms of cancer as follows:

  • A dry cough, pain in the armpits, lumps in both or either one armpit, moderate fever, fatigue and block in the chest triggered after drinking alcohol may be the signs of Hodgkin lymphoma
  • A dark mole, black, blue, or brown in color can be a sign of a highly severe skin cancer known as Melanoma.
  • If there are oversized lymph nodes in the armpit as well as above the clavicle or a non-tender lump in either one of the breasts, it may be an early sign of Breast cancer.
  • Paleness, oversized lymph nodes, spleen, fatigue, and repeated infections may be the result of a cancer of white blood cells known as Leukemia.
  • Coughing out blood or a dry cough, pain in the chest and oversized inflamed lymph nodes in the armpit can be signs of advanced lung cancer.

More reasons for trouble-free lumps in the armpits:

  • Painless lumps in the armpits can also result from the allergic reaction from iodine, penicillin, or sulfa drugs.
  • Silicone breast implants can also cause trouble-free lumps in the armpits.

Tough, inactive lumps in the armpits can be an early sign of cancer.

Agonizing Armpit Rash

Painful rashes in the armpit can result from:

  • Bacterial folliculitis
  • Ringworm, a fungal infection
  • Ingrown hair after shaving
  • Miliaria or Sweat rash.
  • Fox-Fordyce disease that can clog sweat glands
  • Overuse of deodorants can cause armpit rashes owing to allergic contact dermatitis
  • Infected hair follicles in the armpit can sometimes result in a Boil (furuncle)
  • An infection caused by the Corynebacterium knew as Erythrasma
  • Hidradenitis suppurative is hair follicles infection and can cause chronic inflammation.
  • Inverse psoriasis

Armpit Ache in Women

Cyclic breast pain that starts after ovulation can cause severe pain in the top portion of breasts and continue towards the armpits or hands on both or either one side, but it gets resolved with the beginning of menstrual periods.

A breast inflammation called Mastitis is a result of an infection contracted during breastfeeding. Swollen red breasts on both or either one side, as well as oversized and aching lymph nodes in the respective armpit, are the symptoms of Mastitis.

Unusual Reasons for Armpit Ache

While flu, tonsillitis, common cold, scarlet fever, chicken pox, ear infection, strep throat (pharyngitis), tooth abscess, thyroid cancer, or throat cancer (laryngeal or pharyngeal) are more likely to cause oversized neck lymph nodes, but can also found in the armpit area.

Angina pectoris, heart attack or heartburn may cause pain in the armpit, but these conditions are more likely to cause pain at the top section of the back or behind the breastbone.

Armpit pain can sometimes unusually result from hypothyroidism and hyperthyroidism

Fibromyalgia can’t originate armpit pain generally but very much possible trigger upper chest, back, and neck pain.

Warts and skin tags (soft skin stalks) are less likely to cause pain in the armpits.

FAQs about Armpit Pain

Can skin cancer result in the armpit?

Skin cancer rarely occurs in the armpits. However, a type of cancer known as Melanoma on the back can lead to oversized lymph nodes in an armpit.

Skin cancer rarely occurs in armpits. As a result, melanoma on the back side can link to enlarged armpit lymph nodes.

Is there any condition that causes ache generally in or close to the right or left armpit?

No. Heart-specific pain experienced on the upper arm or left shoulder instead of armpit.


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