What's Causing My Left Breast Pain?

What are the causes of left breast pain? This symptom has many possible causes—some that are due to breast issues and some that are not. The first priority when you have pain in the left breast is to make sure it isn't your heart.

First Step—Check Your Heart

While your left breast pain is most likely due to something else, the first question you need to ask yourself is whether you could be having symptoms of a heart attack. Keep in mind that the symptoms of heart disease in women are often very different from those in men. Pain may be mild, feel like a burning pain, or may simply feel like breast pain. Due to the often vague and subtle symptoms, women are more likely to overlook the signs, and, as a result, die from a heart attack.

Everyone should be familiar with the symptoms of a heart attack, which may include:

  • Chest pain or pressure (however, a quarter to a third of people having a heart attack do not experience any chest pain or pressure)
  • Pain in your neck, jaw, or left arm
  • Shortness of breath (especially common in women having a heart attack)
  • Sweating
  • Nausea
  • Lightheadedness or passing out
  • A feeling that something just isn't right or a sense of impending doom

If you're uncertain about the origin of your pain and have any risk factors for heart disease, it's better to be on the safe side and seek immediate medical attention.

What's the Origin?

After making sure you don't need to call 9-1-1, the first step in figuring out the source of left-sided breast pain is to decide whether your pain is originating in your breast or instead related to other structures above or beneath your breast. Sometimes this is hard to determine, and you should consider both breast and non-breast causes. 

The location in which we sense pain does not necessarily tell us the location of a medical problem. Some of the nerves in our body are very specific. For example, a sensation on your fingertip can usually be located very precisely.

Other nerves are not as specific. They alert you to the general area of your body affected by some process, but they don't locate the precise area of the problem as accurately. It's common not to know whether the pain you're feeling is in your breasts rather than some other structure in the general vicinity of your left breast. 

Breast-Related Causes

breast related causes of left breast pain

Verywell / Emily Roberts

Several conditions of the breast may cause left-sided breast pain alone, including:

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

Injuries

Your breasts are covered with sensitive, elastic skin that protects nerves, blood vessels, and connective tissues as well as ducts and lobes for producing breast milk. If you've had a breast injury, you can expect bruising and an ache that will persist until the skin and underlying tissues have healed.

Sometimes an injury to the breast heals with scar tissue, and this scar tissue can cause pain (fat necrosis). Fat necrosis may appear as a hard lump as well, making it difficult to distinguish from breast cancer, even on imaging tests such as a mammogram.

Breast Surgery 

After any type of breast surgery—whether it is an augmentation, reduction, or reconstruction—your breasts will hurt as incisions heal and scar tissue develops. And as with scar tissue related to an injury, pain can come and go even 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

Milk Duct Conditions and Infections

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

  • An abscess may occur under your nipple or areola, causing pain, redness, and heat.
  • Milk ducts can become clogged, causing a firm, tender lump.
  • If a clogged duct becomes infected, it can cause mastitis (breast inflammation), which makes breasts swollen, tender, warm, and red, or ductal ectasia, which can cause tenderness, irritation, redness, and possibly a thick, sticky discharge from the nipple.
  • Breast cysts and fibroadenomas may grow and crowd your milk system or connective tissue, creating aches and pains.

See Your Doctor

If you suspect a breast infection or inflammation, it's important to visit your family doctor or gynecologist. You may need to take antibiotics or other prescription medications to clear up the problem.

Hormonal Causes

Hormone changes may also cause breast tenderness, especially when levels change during your menstrual cycle or while on hormones such as oral contraceptive pills, infertility treatments, or hormone replacement therapy. The pain may be felt in one or both breasts, and to a greater degree in one breast. It also may radiate to the armpit.

Hypothyroidism—characterized by a low level of thyroid hormones in the body—may also be linked to hormone fluctuations and benign breast disorders that cause breast pain. Graves' disease, which is an autoimmune disorder involving excess thyroid hormone, is also associated with breast changes that can lead to pain. The nature of the pain depends on what specific breast changes occur.

Lumps

Finally, whenever you find breast lumps or bumps that are not related to your menstrual cycle, or even if they are related to it, consult with your doctor right away to get a clear diagnosis and proper treatment. While your doctor may be able to make a good guess as to whether a lump is benign or malignant, imaging tests and sometimes a biopsy may be needed to be sure.

Left-Sided Breast Cancer

Most of the time—but certainly not always—breast cancer is painless in the early stages. There are exceptions to this rule, though, especially with cancers such as inflammatory breast cancer.

Inflammatory breast cancer is an aggressive form of breast cancer that usually begins with pain, redness, and swelling in the breast. Most people are unable to feel a discreet lump, and cancer often resembles an infection. Early on, the only symptom may be the pain in one breast or the other.

Breast cancer in women occurs slightly more often on the left side than the right, although it occurs equally on both sides in men. While breast pain is more likely to be due to something other than breast cancer, roughly one in six women with breast cancer have breast pain during the 90-day period prior to diagnosis.

Non-Breast Related Causes

Non-breast related causes of left breast pain

Verywell / Emily Roberts

Sometimes when pain happens, it is hard to tell exactly what hurts and where the pain is centered. When pain hits you on the left side of your chest, you may think it is left breast pain, but the pain may actually be beneath your left breast. Some non-breast related causes of pain that feel like it is in your breast include:

  • Chest wall pain
  • Esophageal causes
  • Fibromyalgia
  • Lung-related causes

Chest Wall Pain

Below your breast are chest wall muscles that may spasm during times of anxiety and stress, causing pain that may last just a few seconds or several days. Chest wall pain that results from inflammation of the cartilage between the breastbone and ribs is called costochondritis.

Chest wall pain can cause a sharp, stabbing pain. It's more common on the left side but can be on both sides or, less often, only on the right. It ranges from mild to severe and usually is painful to the touch. The pain may radiate to your back or stomach and get worse when you take a deep breath. Pains may shoot down the arms as well.

If you pull a chest muscle or have an injury to the left side of your chest, aches and pains may result.

Esophageal Causes

Since your esophagus runs below your left breast, gastroesophageal reflux disease (GERD) can occasionally feel like left breast pain. A related condition, hiatal hernia, may cause similar symptoms.

Pain related to the esophagus may feel more like a burning pain, and you may have associated symptoms like an acidic taste in your mouth, but not always. Other digestive-system conditions such as liver disease may also, at times, cause pain that feels like it is coming from your breast.

Fibromyalgia

Fibromyalgia may cause pain anywhere in your body, and chest pain is not uncommon. Fibromyalgia pain comes from a disordered nervous system and can affect not only nerves, but muscles, joints, and connective tissues. It can create generalized, diffuse pain or sharply focused pain.

The nature of the pain can be dull and achy or sharp, stabbing, burning, or tingling. Fibromyalgia pain is notably not associated with inflammation, redness, or warmth. Very often, fibromyalgia pain is made worse by putting pressure on the area, a symptom called tactile allodynia.

Lung-Related Causes

Pneumonia is an infection that causes inflammation in the air sacs in your lungs. Because your lungs are in the chest and behind your breasts, pneumonia can cause left-sided pain that may be mistaken for breast pain.

Pulmonary emboli are blood clots, usually from the arms or legs, that break off and travel to your lungs. They also can cause pain that feels like it is coming from your breast. Other symptoms include sudden shortness of breath and coughing. Pulmonary emboli are medical emergencies that require immediate treatment.

Skin-Related Causes

Sometimes women develop pain that feels like it's either in the skin or on the outer surface of the breast. This may be shingles, a condition caused by the reactivation of the virus that causes chickenpox (the varicella-zoster virus) years or decades after the primary infection.

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

What Should You Do?

There are a number of causes of left-sided breast pain, some more serious than others. The only way to know for sure what's causing your pain is to seek medical attention. 

Whether your left breast pain is due to a minor nuisance condition or a larger problem such as breast cancer or even heart disease, it's important to get an answer to the question of what is causing your pain. Pain is our body's way of alerting us to a problem. 

If you've seen your doctor but still lack an adequate explanation for your pain, call again. You may need to consider getting a second opinion if the pain persists.

Finally, keep in mind that even with an explanation, it's certainly not unheard of for a person to have more than one process being responsible for pain. For example, you may have a common breast condition such as a breast cyst along with the common condition costochondritis. In fact, it's not uncommon for people to receive a diagnosis of cancer after an evaluation for a seemingly unrelated concern.

When to Call the Doctor

Call the doctor for your breast pain if:

  • 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
  • It lasts longer than two weeks
  • It stays in one spot
  • It gets progressively worse
  • It starts imposing limits on your activity

Frequently Asked Questions

Can my choice of undergarment contribute to breast pain?

Yes. Make sure you wear the appropriate size bra with proper support for your chest size. Incorrect fit can cause sagging and pulling, which then causes discomfort in the breasts.

Which organs are located under the left breast?

Directly under and slightly below the left breast, your internal organs include the heart, spleen, stomach, pancreas, and large intestine. The sternum and rib cage cover and protect these organs, and therefore are also beneath the breasts.

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Article Sources
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