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Why Do I Have Breast Pain on One Side? 9 Breast Pain Causes

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Last updated January 13, 2021

Breast pain questionnaire

Use our free symptom checker to find out what's causing your pain.

Do you have breast pain before your period? After menopause? Learn about the hormonal, structural and cancerous causes of breast pain on the right or left side.

Breast pain questionnaire

Use our free symptom checker to find out what's causing your pain.

Breast pain symptom checker

Breast pain symptoms

The breasts are composed of tissue, fat, and glands that develop due to increases in hormones such as estrogen during puberty. Breast pain, or mastalgia, is a common condition among women of childbearing age; however, it is commonly described as cyclical or non-cyclical.

Common characteristics of breast pain

Breast pain can differ from woman to woman, but common breast pain symptoms often include:

  • Tenderness
  • Sharpness or burning
  • Tightness around the breast tissue

Cyclical breast pain

Women in their early 20s and 30s are most likely to experience symptoms related to cyclical breast pain. Cyclical breast pain often involves both breasts and includes symptoms such as the following.

  • Occurring in close relation to your menstrual cycle: It may begin a few days before the start of your cycle
  • Sensation of fullness or heaviness in the breasts
  • Breast swelling
  • Radiating pain: Pain that radiates to the underarm or upper and outer portions of the breast
  • Self-resolving: Improves during your menstrual cycle and resolves on its own when the menstrual cycle is over

Non-cyclical breast pain

Women in their 40s to 50s who are transitioning or experiencing menopause often experience non-cyclical breast pain symptoms. Non-cyclical breast pain usually involves one breast and includes symptoms such as the following.

  • Burning or soreness of the breast
  • Constant pain: Pain will last throughout the month that is unrelated to the menstrual cycle.

Breast pain causes

Fortunately, the majority of breast pain causes are limited and not life-threatening. However, it is still important to follow-up on your breast pain symptoms with your physician in order to get an appropriate diagnosis and care.

Hormonal causes

Breast pain is divided into cyclical and non-cyclical causes because cyclical pain is associated with hormonal fluctuations in estrogen and progesterone. The breasts are extremely sensitive to these hormone changes and often worsen as women get older due to increased sensitivity of the breasts.

Breastfeeding-related causes

Breastfeeding can result in pain due to the latching of the infant itself. If your baby is latching improperly you will experience breast pain symptoms. Moreover, you may experience breast pain due to problems associated with breastfeeding below:

  • Infection: Infection of the milk ducts of the breast is known as mastitis. Mastitis can result in cracked, burning or blistering nipples that may also cause red streaks on the breast. Though painful, this condition is common among women breastfeeding.
  • Engorgement: When the breasts become too full of milk, they enlarge and press against the skin, resulting in a tight, painful sensation.

Structural causes

Structural causes of breast pain may include the following.

  • Size: Women with breasts that are larger or not proportional to their frames can experience breast pain that is related to pain in their neck and shoulder pain.
  • Extramammary: Pain or irritation of the chest, arms, or back muscles due to exercises and activities such as rowing, waterskiing, raking or shoveling can radiate to and affect the breasts.

Cancerous causes

Though less common, breast pain can signal cancerous conditions. Be on alert and make an appointment with your physician immediately if you notice breast pain, especially if the pain is associated with other symptoms, such as:

  • A new, fixed lump in the breast
  • Changes in size or shape of the breast
  • Changes other characteristics: Such as in the color (redness, inflammation) or texture of the skin (wrinkling, puckering or dimpling)
  • Rash, crusting of nipple discharge

10 breast pain conditions

The list below shows results from the use of our quiz by Buoy users who experienced breast pain. This list does not constitute medical advice and may not accurately represent what you have.

Fibrocystic breast changes

Fibrocystic change is a generalized term used to describe a variety of benign changes in the breast. Symptoms of this condition are breast swelling or pain, as well as nodules, lumpiness, or nipple discharge.

Rarity: Common

Top Symptoms: breast lump, hard breast lump, nipple discharge, rope-like breast lump

Symptoms that always occur with fibrocystic breast changes: breast lump

Urgency: Primary care doctor

Premenstrual syndrome

Premenstrual syndrome (PMS) is a condition that can produce emotional and physical symptoms in women in the days leading up to their menstrual cycle. Common symptoms include bloating, cramping, headaches, irritability, fatigue, and sleep and appetite changes. These symptoms..

Breast pain questionnaire

Use our free symptom checker to find out what's causing your pain.

Breast pain symptom checker

Possible pregnancy

The earliest sign of pregnancy is typically a missed period, but many women do experience symptoms shortly after conception:

  • Implantation bleeding may occur after six to twelve days, when the fertilized egg implants itself into the lining of the uterus. This can cause mild cramping with light bleeding or spotting.
  • Fatigue and increased desire to sleep may happen within a week.
  • Breast tenderness can start as soon as one to two weeks.
  • Nausea ("morning sickness") can occur after two to eight weeks.

If pregnancy is suspected, testing should be done so that proper prenatal care can begin. It's important to avoid some behaviors during pregnancy, such as drinking alcohol or using certain drugs or medications, so an early diagnosis should be made.

Over-the-counter home pregnancy tests are available at any drugstore. A positive test is almost certainly correct, but a negative test in the face of other symptoms may be a false negative and should be tried again after a week.

Rarity: Common

Top Symptoms: fatigue, nausea or vomiting, stomach bloating, bloody vaginal discharge, vaginal bleeding

Symptoms that always occur with possible pregnancy: missed period

Symptoms that never occur with possible pregnancy: painful urination, severe abdominal pain

Urgency: Self-treatment

Breast infection (mastitis)

Mastitis is an infection of the breast tissue that results in breast pain, swelling, warmth and redness of the breast. Mastitis most commonly affects women who are breast-feeding (lactation mastitis), although sometimes this condition can occur in women who aren't breast-feeding.

Rarity: Uncommon

Top Symptoms: fatigue, nausea, breast pain, signs of breast inflammation like redness, swelling or fever, fever

Symptoms that always occur with breast infection (mastitis): breast pain, signs of breast inflammation like redness, swelling or fever

Urgency: Primary care doctor

Breast cyst

A breast cyst is a fluid-filled sac (like a tiny balloon) inside the breast. Breast cysts are common in women. They might cause a little pain, but they are usually benign (not cancerous).

Rarity: Common

Top Symptoms: breast pain, breast lump, painful breast lump, movable breast lump

Symptoms that always occur with breast cyst: breast lump

Symptoms that never occur with breast cyst: armpit lump, fever

Urgency: Primary care doctor


A fibroadenoma is a benign (non-cancerous) breast tumor. It is the most common kind of breast tumor in young women. Fibroadenomas result from overgrown cells forming a mass (-oma) of breast tissue including fibrous (fibro-) and glandular (-adeno-) components.

Some fibroadenomas remain unnoticed unti..

Premenstrual dysphoric disorder

Premenstrual dysphoric disorder (PMDD) describes a set of severe, debilitating symptoms that appear seven to ten days before a woman's menstrual period begins.

It may be caused by an abnormal reaction to the natural female hormone changes, creating a deficiency in the mood-regulating brain chemical serotonin.

Risk factors include a personal or family history of PMDD, postpartum depression, and/or general depression, as well as cigarette smoking.

Physical symptoms include headaches, abdominal pain and bloating, back pain, and breast tenderness. Psychological symptoms include severe depression, anxiety, and irritability.

Because symptoms tend to get worse over time, medical help should be sought so that quality of life can be improved.

If symptoms persist for a year or more, a diagnosis of PMDD may be made.

Treatment includes improving the diet, adding vitamin and mineral supplements, and getting regular exercise.

Birth control pills to regulate the menstrual cycle may be prescribed, along with anti-inflammatory medicines such as ibuprofen. Antidepressants in the selective serotonin reuptake inhibitor class (SSRI) are helpful in some cases.

Rarity: Common

Top Symptoms: fatigue, stomach bloating, anxiety, depressed mood, abdominal cramps (stomach cramps)

Symptoms that always occur with premenstrual dysphoric disorder: impaired social or occupational functioning, symptoms of depression, anxiety and emotional lability

Symptoms that never occur with premenstrual dysphoric disorder: constant sadness, disapearance of periods for over a year

Urgency: Primary care doctor

Non-specific breast pain

Nonspecific breast pain, also called mastalgia or mastodynia, refers to tenderness or pain in the breast with no obvious cause. It almost always proves to have a benign (non-cancerous) cause.

Breast pain is most common in women aged 35 to 50 and still experiencing menstruation. Fibrocystic changes are common in this age group, where tiny, fluid-filled sacs form within breast tissue and might be felt as small, tender, but non-cancerous lumps.

Birth control pills, hormone replacement therapy, caffeine, and soy can cause breast tenderness in women of any age. A breast infection can cause painful lumps.

A medical provider should be seen, in order to rule out any serious condition and get treatment for the discomfort.

Diagnosis is made through patient history; physical examination; mammogram or breast ultrasound; and sometimes biopsy.

A breast infection will be treated with antibiotics. Large, painful cysts may have the fluid drained or be surgically removed. Lifestyle improvements regarding diet and exercise are often helpful, as well as adjustments to birth control pills or hormone therapy.

Rarity: Common

Top Symptoms: breast pain, breast swelling, armpit pain

Symptoms that always occur with non-specific breast pain: breast pain

Urgency: Primary care doctor

Breast cancer

There are several types of breast cancer, depending on the part of the breast where it starts. The most common types are ductal carcinoma in situ (DCIS), invasive ductal carcinoma and invasive lobular carcinoma.

Women over age 50 with a family history of the disease, and/or certain genetic factors, are most at risk, but anyone can get breast cancer at any age. It is rare in men but does occur.

Symptoms include a lump, thickening, or pain anywhere in the breast or armpit; red, flaky, or irritated breast or nipple skin; nipple discharge; and any area of irregular skin or misshapenness.

Many harmless conditions can cause similar signs, so it is important to see a medical provider about any of these symptoms.

Diagnosis is made through physical examination; imaging such as ultrasound, mammogram, or MRI; and sometimes biopsy.

Treatment involves a combination of surgery, radiation therapy, and chemotherapy.

The best prevention is a combination of screening mammograms as recommended by the medical provider, and monthly self-examination.

Rarity: Uncommon

Top Symptoms: breast pain, armpit lump, breast mass or retraction, breast lump, nipple discharge

Urgency: Primary care doctor

Breast abscess

A breast abscess is a collection of infected fluid, or pus, within the breast that is generally painful, and may cause fever, chills, fatigue, and body aches.

A breast abscess is a complication of mastitis, an infection of the breast tissue, that develops most commonly in breastfeeding women. ..

Breast pain questionnaire

Use our free symptom checker to find out what's causing your pain.

Breast pain symptom checker

Breast pain treatments and relief

At-home treatments

Luckily, cyclical breast pain can be treated at home with simple lifestyle changes such as the following.

  • Choose the right bra: Invest in a supportive and comfortable bra that you can wear when your pain is at its worst.
  • Pain medication: Take over-the-counter medications such as ibuprofen (Advil, Motrin) or acetaminophen (Tylenol) in order to relieve breast pain symptoms.
  • Heat or ice: Use hot or cold compresses on the breast to reduce swelling and pain.
  • For breastfeeding: If your pain is related to breastfeeding, try pumping your breast milk to prevent engorgement and see a lactation specialist to help train your baby in proper latching.

When to see a doctor

Make an appointment with your physician if your breast pain:

  • Persists for a long time: More than a couple of weeks
  • Is localized: Is limited to only one specific area of your breast
  • Is worsening over time despite at-home remedies
  • Begins to interfere with everyday activity

Medical treatments

To address cyclical breast pain symptoms, your physician may also prescribe oral contraceptives or estrogen blockers to control your hormone levels. Your physician will provide antibiotics if your breast pain is related to mastitis.

FAQs about breast pain

Here are some frequently asked questions about breast pain.

Why do I only have breast pain in one breast?

There are many causes of pain in one breast and not the other. Usually, this type of pain is not associated with a menstrual cycle. If it is associated with a menstrual cycle, it is more likely to be caused by cyclical changes in breast tissue. Non-cyclical causes include things like diet and lifestyle, such as smoking, having larger breasts, or wearing poorly fitted bras. Ductal ectasia, when the ducts of the breast dilate, may also lead to breast pain on one side. Infections of breastfeeding mothers like mastitis can also lead to swelling, warmth, and one-sided breast pain.

Why do I have breast pain before my periods?

You likely have breast pain before your period because of fibrocystic breast changes. These changes occur as your hormones prepare you to menstruate and cause changes in your breast tissue, resulting in tenderness.

What causes breast pain after menopause?

Breast pain after menopause is caused most frequently by hormone replacement therapy, as female hormones cause increased sensitivity of the breast tissue. This may spontaneously resolve over time if you continue to take your medications regularly.

Can stress and anxiety cause breast pain?

No, stress and anxiety generally do not cause breast pain. Severe physical stress among individuals who are undergoing situations, like starvation or a severe bodily injury, may cause menstruation to stop as well as cyclical pains associated with menstruation.

What does it feel like when your breasts are tender?

If a breast is tender, it may mean that the entire breast hurts and is sensitive to touch. This sort of tenderness may indicate a problem with the skin, such as an infection or other cause of inflammation. Tenderness can also occur at the nipple or within the breast tissue when pressed upon. This can be caused by natural changes associated with aging, a menstrual period, a benign cyst, or even more dangerous issues such as infections or malignancies.

Questions your doctor may ask about breast pain

  • Do your symptoms occur or worsen before or during your period?
  • Any fever today or during the last week?
  • Have you given birth to any children?
  • When was your last menstrual period?

Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.

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Dr. Rothschild has been a faculty member at Brigham and Women’s Hospital where he is an Associate Professor of Medicine at Harvard Medical School. He currently practices as a hospitalist at Newton Wellesley Hospital. In 1978, Dr. Rothschild received his MD at the Medical College of Wisconsin and trained in internal medicine followed by a fellowship in critical care medicine. He also received an MP...
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