What Causes Pain Under the Left Breast?

Pain under the left breast could have many possible causes, such as a muscle strain, infection, or hormone changes. Several internal organs can also cause pain that radiates to the left breast, including the heart, lungs, stomach, and pancreas.

In some cases, sudden sharp pain under the left breast can be a sign of a life-threatening condition, such as a heart attack, pulmonary embolism, or cancer. For this reason, you should always have breast pain evaluated by a healthcare provider before considering other causes.

Heart-Related Causes

Some causes of left breast pain are related to the breast itself; others are not. Left breast pain can be a symptom of a heart-related issue, such as angina, heart attack, or pericarditis.

Angina

Angina is chest pain caused by a lack of oxygen getting to the heart. People with stable angina, who may be living with coronary blockages, can feel this pain regularly when they exercise or exert themselves too much. If angina becomes worse, it can lead to a heart attack.

Angina pain may last a few minutes but should go away with rest. In addition to chest pain, you may experience other symptoms such as:

• Nausea
• Lightheadedness
• Numbness
• Palpitations
• Discomfort around the upper abdomen
• Sweating

Treatment for angina involves lifestyle changes and medication that can help prevent a fatal heart attack, which may include aspirin, statins, and beta-blockers.

Heart Attack

Symptoms of a heart attack may vary, but common signs include:

• Pressure or squeezing in the chest: It may last just a few minutes or come and go.
• Pain or discomfort in other areas of the upper body: You may feel it in your arms, back, neck, or jaw area.
• Shortness of breath
• Sweating
• Nausea
• Lightheadedness or passing out

The symptoms of heart attack in females may include:

• Mild pain
• Burning
• An uncomfortable feeling in the breast

These are often different than symptoms of a heart attack in males. Unfortunately, the often vague and subtle symptoms lead women to overlook the signs. Too often, that's a fatal mistake.

Pericarditis

Pericarditis is a common cause of chest pain that results from inflammation of the pericardium, the protective tissue surrounding the heart muscle.

This condition can cause sudden, sharp chest pain that worsens if you lie down or breathe deeply. It may feel like a heart attack, but it's not life-threatening.

Nonsteroidal anti-inflammatory drugs (NSAID), such as aspirin, Advil, and Motrin (ibuprofen), can help relieve the pain. This may be combined with another anti-inflammatory medication, colchicine, which helps reduce the chances of pericarditis recurring.

However, the underlying reason for the inflammation needs to be treated as well. These can include the following:

• Bacterial infection, including tuberculosis
• Trauma (such as from a car accident)
• Hypothyroidism
• Cancer
• Autoimmune diseases such as lupus or rheumatoid arthritis

Digestive Causes

Certain issues related to your upper digestive tract may lead to pain under the left breast. They include:

• Heartburn may cause a burning sensation, chest pain, or other symptoms like an acidic taste in your mouth. For mild heartburn, treatment may include an antacid and avoidance of acidic, high-fat, or spicy foods and drinks.
• reflux diseaseGastroesophageal (GERD) can feel like left breast pain. For more severe cases of GERD, you may be put on an acid-reducing medication, such as an H2 blocker or a proton pump inhibitor.
• Hiatal hernia may also cause GERD-like symptoms. Symptoms may be treated with medication and lifestyle changes. In severe cases, surgery may be required.
• Pancreatitis is caused by inflammation of the pancreas. It is usually felt in the middle left abdomen but may be felt higher up, under the left breast. Pancreatitis can be a serious condition and may require hospitalization and supportive care.

You should notice an improvement in your pain once the digestive problem is under control. If you don't, let your healthcare provider know.

Lung-Related Causes

Your lungs sit behind your breasts. A few lung-related conditions can cause pain that's mistaken for breast pain. They include:

• Pneumonia: Pneumonia is a lung infection that can cause pain under the breast when you inhale along with other symptoms like cough and fever. Treatment may involve antibacterial, antiviral, or antifungal medication.
• Pleurisy: This is an inflammation of the membrane that covers your lungs and can cause sharp or stabbing pain when you inhale. Treatment involves pain medications such as NSAIDs or codeine.
• Pulmonary embolism: This is a blood clot that blocks a blood vessel in the lungs. Symptoms may include pain along with shortness of breath, anxiety, coughing, and heart palpitations. It may be treated with medication, a catheter, or surgery.
  

Musculoskeletal Causes

Conditions affecting the chest wall can sometimes result in left breast pain. Musculoskeletal chest wall pain may:

• Appear on either side (though it's less common on the right)
• Range from mild to severe
• Be painful to the touch
• Radiate to your back, arms, or stomach and can feel sharp or stabbing
• Get worse when you take a deep breath

Common causes of chest wall pain include:

• Musculoskeletal injury: You may experience chest wall pain if you strain or injure a muscle in your chest or you have a bruise or rib fracture. This type of chest pain may feel worse when you inhale.
• Costochondritis and Tietze syndrome: These are similar conditions that cause inflammation of the cartilage between the breastbone and ribs. They usually get better within a few days to weeks.
• Precordial catch syndrome: This is a benign condition that can cause brief, sharp pain under the left breast that comes and goes.

You can treat minor chest wall pain by taking an NSAID and applying a cold compress to the affected area. If the pain doesn't improve despite taking a painkiller, let your healthcare provider know.

Fibromyalgia

Fibromyalgia is a chronic pain condition. It can cause pain anywhere in your body, including the chest.

Fibromyalgia pain comes from a disordered nervous system. It affects not only nerves, but muscles, joints, and connective tissues. The pain is usually:

• Generalized and diffuse or sharply focused
• Dull and achy, sharp, stabbing, burning, or tingling
• Not tied to inflammation, redness, or warmth.

Very often, fibromyalgia pain is made worse with gentle pressure. This is called tactile allodynia. While there is no cure for fibromyalgia, several medications are available to help with pain.

Shingles

Sometimes pain feels like it's either in the skin or on the outer surface of the breast. This may be shingles.

The condition is caused by a reactivation of the virus that causes chickenpox (the varicella-zoster virus). It can come on years or decades after you have chickenpox.

The initial tenderness is generally followed by a painful rash. Because the rash is the more recognizable symptom, shingles can be hard to recognize early on.

Treatment for shingles involves taking antiviral drugs. Pain and other shingles symptoms should resolve once the infection is treated.

Noncancerous Breast-Related Causes

Several breast conditions unrelated to breast cancer may cause pain in or under the left breast. They include:

• Injuries
• Breast surgery
• Milk duct conditions and infections
• Hormonal causes
• Lumps

Injuries

If you've had a breast injury, bruising and aches may last until the injury heals.

Sometimes an injury to the breast causes scar tissue. Scar tissue can cause pain and fat necrosis, a breakdown of fatty tissue. It may appear as a hard lump. These lumps are hard to distinguish from breast cancer, even on a mammogram.

If you are experiencing mild breast pain due to a minor injury, use the following to reduce pain and inflammation:

• Wrap an ice pack with a towel and apply it to the injured breast for 10 to 15 minutes to reduce swelling.
• Take an NSAID medication for pain relief, such as Advil (ibuprofen) or Aleve (naproxen).
• Avoid wearing bras that are tight or have underwires.

Contact your healthcare provider if your pain does not improve after icing and using painkillers.

Breast Surgery 

After any type of breast surgery—augmentation, reduction, or reconstruction—your breasts will hurt as the incisions heal and scar tissue develops.

As with scar tissue from an injury, pain can come and go long after your surgery. Depending on the type of surgery, you may experience:

• Burning pains in your nipples
• Sharp, shooting pains in your breast
• A tightness or cramping sensation in your breasts, shoulders, neck, and back
• Nerve pain (burning, pricking, or shock-like sensations) in the breast, chest, arm, or armpit

Your healthcare provider will likely prescribe painkillers for your recovery. They may also provide instructions for hot and/or cold compresses to help relieve breast pain and swelling. Take care to follow their instructions carefully.

If you still experience pain despite taking painkillers, let your healthcare provider know. In some cases, prolonged pain following surgery can be a sign of nerve damage caused by the surgery itself. Your provider can prescribe medication to help with nerve pain.

Milk Duct Conditions and Infections

Several benign but painful conditions can develop inside your breast milk ducts:

• An abscess under your nipple or areola can cause pain, redness, and heat.
• Clogged milk ducts can cause a firm, tender lump. Clogged milk ducts also tend to resolve on their own without treatment.
• Mastitis is an infection in a clogged duct. It makes the breast swollen, tender, warm, and red.
• Ductal ectasia is another possible infection. It causes tenderness, irritation, redness, and possibly a thick, sticky discharge from the nipple.
• Breast cysts and fibroadenomas are growths that may crowd breast structures, creating aches and pains. Most breast cysts go away by themselves and do not require any treatment, although a lump in the breast should always be checked by a healthcare provider to ensure it is benign (not harmful).

Hormonal Causes

Reproductive hormone changes may cause breast tenderness. You may feel pain in one or both breasts. It may be worse on one side. You might also feel it in your armpit.

That's especially true during the fluctuations of your menstrual cycle. This may also occur with birth control pills, infertility treatments, and hormone replacement therapy.

The nature of the pain along with how it's treated depends on the specific breast changes. If your pain is a side effect of another medication, your provider may switch your treatment to one that has a lesser effect on your hormones.

Thyroid diseases can lead to benign (noncancerous) breast changes that cause pain. These include:

• Hypothyroidism (low thyroid hormones)
• Graves' disease (an autoimmune disorder involving excess thyroid hormone)

For breast pain due to thyroid dysfunction, your pain should resolve once your thyroid condition is under control. Treatment will likely entail thyroid medication (e.g. levothyroxine for hypothyroidism) to return your thyroid hormones to a healthy level.

Lumps

Breast lumps can show up at certain stages of your menstrual cycle. If you find lumps at other times, see your healthcare provider right away. It's even a good idea to get lumps that are related to your cycle checked out.

Your provider can take the steps necessary to see whether a lump is benign or malignant (cancerous). They'll likely use imaging tests and possibly a biopsy.

Pregnancy

Under the influence of the hormones estrogen and progesterone, breasts undergo many changes during pregnancy to prepare for lactation (milk production) and the possibility of breastfeeding.

As the breasts develop and increase in size and volume, you may notice that they feel especially tender and full and that the nipples are more sensitive.

Tender, swollen breasts are often one of the earliest signs of pregnancy, appearing as early as one to two weeks after conception.

Many people find that applying a cold compress to sore breasts is helpful. Wearing loose clothes and a well-fitted bra for extra support is also recommended.

Left-Sided Breast Cancer

Breast cancer is usually (but not always) painless in the early stages. A notable exception is inflammatory breast cancer.

This is an aggressive breast cancer that usually begins with:

• Pain
• Redness
• Swelling in the breast

This cancer often resembles an infection. Most of the time, you can't feel a lump. The only early symptom may be pain in one breast.

Breast cancer in female breast tissue occurs slightly more often on the left side than the right. It occurs equally on both sides in male breast tissue.

Breast pain is likely due to something other than cancer. Nonetheless, if you feel a lump in your breast or are experiencing unusual swelling, with or without pain, you should always see a healthcare provider for an evaluation.

When to See a Healthcare Provider

Left-sided breast pain has many causes. Some are more serious than others. The only way to know for sure what's causing your pain is to get medical attention. 

Contact your healthcare provider if you experience the following with breast pain:

• It lasts longer than two weeks.
• It stays in one spot.
• It gets progressively worse.
• It limits your activity.
• You have a painful lump that doesn't go away after your period.
• Your breasts are red or swollen.
• You have pus drainage or nipple discharge.
• You have other concerning symptoms such as a rash or fever.

Pain is your body's way of alerting you to a problem. Don't ignore it or assume it's harmless.

If your healthcare provider doesn't find an explanation for your pain, keep pushing for one. If pain persists, consider getting a second opinion.

It's not unheard of to have more than one cause of left breast pain. For example, you may have a breast cyst along with costochondritis.

Summary

The first thing to do when you have sudden sharp left breast pain is to get checked for a heart attack.

Pain under the left breast can come from injuries or conditions that affect the breast tissue and milk ducts. Breast cancer isn't usually painful early on. An exception is inflammatory breast cancer, which also causes redness and swelling.

Pain from other areas felt in the left breast can come from nearby structures like chest muscles, the lungs, or the esophagus. Nerve pain in the area can be from fibromyalgia or shingles.

See your healthcare provider about left breast pain so you can have it diagnosed and treated.