Pain under your left breast can send up some red flags, especially because chest pain in general is related to so many health conditions. Figuring out what you’re dealing with can take some detective work—it could be related to an injury, your gut health, your heart, or even your breasts themselves.

Whether it’s a dull, constant ache or a sharp pain in the left breast that comes and goes, discomfort in this area “has a wide variety of causes,” says David Cutler, MD, a board-certified family physician at Providence Saint John’s Medical Center in Santa Monica, California. “This vast array of diagnoses range from minor issues to more serious medical problems.”

In other words? It’s tough to self-diagnose pain in your chest region, and if it’s severe or long-lasting, it’s safer to get checked out by a doctor. Here are some of the possible culprits and how to manage your symptoms.

8 causes of pain under your left breast

1. An injury

If you’ve fallen or had a recent blow to your rib area, that could be to blame. “Overuse or injury to the muscles in the chest wall, such as from lifting, stretching, or poor posture, can lead to localized pain,” Dr. Cutler says.

More severe injuries can lead to a broken or fractured rib, which can cause pain when you take a deep breath, press on the area, or bend or twist.

How to treat it: Mild chest muscle injuries will usually get better on their own with time and rest. While you heal, ice or hot packs and NSAID pain relievers (think: ibuprofen) can help you feel more comfortable.

See your doctor if you think you have a broken rib. Most rib fractures are treated with rest, ice, and over-the-counter (OTC) pain relievers. But your doctor also may recommend physical therapy or breathing exercises to help your lungs continue to move normally, per the Mayo Clinic.

2. Costochondritis

Sharp, aching pain that hits on the left side of your breastbone and gets worse when you breathe deeply or cough could be costochondritis—a condition marked by inflammation of the cartilage that connects the ribs to the breastbone, says Dr. Cutler. It doesn’t have a clear cause, but it may be tied to severe coughing and most often affects people over 40, notes the Mayo Clinic.

How to treat it: You should seek emergency medical attention for severe chest pain to rule out serious or life-threatening causes, like a heart attack, the Mayo Clinic recommends. If your care team determines that you have costochondritis, they may recommend taking pain relievers to manage the discomfort until the inflammation calms down (which should happen within a few weeks).

3. GI conditions

Sometimes an issue brewing in your gut can cause pain to radiate upwards under your breast or even into your chest, Dr. Cutler notes. Here are the most common conditions:

Acid reflux or GERD

“Stomach acid backing up into the esophagus can cause burning pain under the breast,” Dr. Cutler says. Acid reflux can happen occasionally from eating rich or fatty foods, spicy foods, chocolate, caffeine, alcohol, or a lot of onions or garlic, especially if you lie down afterwards, per the Cleveland Clinic. When acid reflux happens regularly (more than twice a week), doctors call it gastroesophageal reflux disease or GERD.

How to treat it: An OTC antacid like Tums or Rolaids can soothe an occasional case of reflux by coating your stomach to decrease acid-related discomfort. Your doctor might recommend a more powerful acid suppressant, like a proton pump inhibitor, if you have GERD.

Gastritis

Gastritis, or inflammation of the stomach lining, can cause stomach pain that radiates up to the left side under the breast, Dr. Cutler says. The condition often stems from an infection from the bacteria H. pylori, but heavy alcohol intake, stress, or overuse of NSAID pain medications can also be a trigger, notes the Mayo Clinic. Along with a burning stomach, gastritis can also cause a gnawing sensation in your stomach, nausea, vomiting, or feeling uncomfortably full after you eat.

How to treat it: You and your doctor will need to figure out what’s causing your gastritis before you can treat it. H. pylori infections require antibiotics, but gastritis caused by other things can often be managed with OTC or prescription acid blockers, per the Mayo Clinic.

Hiatal hernia

Hiatal hernias happen when the upper part of the stomach bulges through the large muscle separating the chest and abdomen. “That can potentially cause discomfort or pain under the left breast,” Dr. Cutler says, along with heartburn, unusual fullness after eating, trouble swallowing, or shortness of breath. It’s common in adults over 50, especially those who have obesity, the Mayo Clinic notes.

How to treat it: Hiatal hernias don’t always require treatment, but your doctor may recommend heartburn meds if your hernia is giving you reflux. If that’s not doing enough to manage the problem, you may need surgery to repair the hernia, per the Mayo Clinic.

4. Breast conditions

If you have pain under or around your left (or right) breast, the issue could be breast-related specifically, especially if you’re currently breast- or chestfeeding. Here are some potential issues:

Mastitis

Mastitis, aka inflammation of the breast tissue, most often affects breast- or chestfeeding people, because it’s typically caused by an infection from a clogged milk duct. It can make the affected breast (left or right) hot, red, swollen, and painful while causing flu-like symptoms like fever, chills, and body aches, per Johns Hopkins Medicine.

How to treat it: Talk to your doctor if you think you have mastitis. They may prescribe antibiotics to fight off the infection. Gentle breast massages and ice packs can make you more comfortable. Try to keep up your regular feeding or pumping routine, too, because draining your breast regularly will help prevent the infection from getting worse, Johns Hopkins Medicine notes.

Fibrocystic breasts

Hormone fluctuations that happen throughout your menstrual cycle, especially between ages 30 and 50, can give your breasts a lumpy or ropelike texture, often just before your period. Sometimes they can cause pain or tenderness, too. Usually both breasts are affected (as opposed to just the left one), per the Mayo Clinic.

How to treat it: Fibrocystic breasts aren’t harmful and they don’t increase your risk for breast cancer. But it’s a good idea to let your doctor know about any lumps or changes to your breast tissue, so they can rule out serious causes. Large, painful fibroids can be removed surgically; if they only cause mild symptoms, you can manage the discomfort with OTC pain relievers, hormonal birth control, and wearing a supportive bra, the Mayo Clinic notes.

Breast cancer

In rare instances, breast pain could be a sign of breast cancer. Other possible markers include a lump in your breast or armpit, thickening or swelling around your breast, skin that’s dimpled or irritated, red or flaky skin around the nipple, nipple discharge, or changes to the shape or size of your breast, per the Centers for Disease Control and Prevention (CDC).

How to treat it: See your doctor right away if you think you have any of the above symptoms. Your doctor can order an ultrasound or biopsy, and if needed, recommend the best course of treatment. Getting annual mammograms starting at age 40 (or younger if you have a family history) can help catch breast cancer early, per the American Cancer Society.

5. Nerve conditions

Sometimes an issue with certain nerves can lead to pain in your chest or breast, says Dr. Cutler.

Thoracic neuralgia

Thoracic neuralgia (sometimes called intercostal neuralgia) happens when you have a pinched nerve in your spine that causes pain to radiate into the front of your chest, Dr. Cutler says. The pain can be sharp, stabbing, radiating, or burning, and be accompanied by numbness or tingling. It often happens after an injury or trauma to the back, chest, or rib area, per the National Library of Medicine.

How to treat it: Thoracic neuralgia treatment depends on the underlying cause. Sometimes the pain can be managed with physical therapy, pain medications, or corticosteroids; other times, nerve blocks, or even surgical procedures are a better fit, the National Library of Medicine notes.

Shingles

If you’ve had chickenpox, the virus could reemerge as shingles when you get older, particularly after age 50. Shingles causes the nerves under your skin to get inflamed, leading to pain, burning, and tingling, per the National Library of Medicine. The inflammation and pain usually affects a person’s face, but “if the virus affects the nerves in the chest area, it can cause a painful, burning sensation under the breast,” Dr. Cutler says.

How to treat it: Let your doctor know if you think you have shingles. There’s no cure, but antiviral medications can help you get better faster, especially if you take them within three days of your symptoms starting, the National Library of Medicine notes.

6. Lung conditions

Pain under your left breast could actually be stemming from your lungs. Here are some conditions to consider:

Lung infections

Infections like pneumonia or bronchitis can cause sharp or stabbing chest pain that gets worse when you breathe deeply. Other symptoms, which can range from mild to severe, may include a cough with greenish or blood-tinged mucus, fever or chills, shortness of breath, fatigue, and sharp or stabbing chest pain that gets worse when you breathe deeply, says the American Lung Association.

How to treat it: See your doctor if you think you have a lung infection. Some infections, like bacterial pneumonia, may need antibiotics. Others, like viral pneumonia and bronchitis, may clear up on their own with rest and fluids. But in some cases, your doctor might also opt to prescribe an antiviral medication.

Pleurisy

Pleurisy is an inflammation of the lung lining that can be caused by an infection or autoimmune disease. It’s typically marked by sharp, stabbing chest pain that comes from one specific place, that worsens when you breathe or cough. The pain can be so strong that you might find yourself trying to breathe carefully to minimize your discomfort, per the Mayo Clinic.

How to treat it: Pleurisy treatment depends on the underlying cause. Some infections will require antibiotics, but in other cases, your doctor may recommend pain relievers or corticosteroids to ease your discomfort. If fluid is building up in your lungs, you may need to have it drained.

7. Heart conditions

Breast or chest pain, especially pain on the left side, could be a sign that something is going on with your heart, Dr. Cutler says. If you’re having severe or unrelenting chest pain, you should seek medical attention ASAP.

Angina

Angina is a type of chest pain that happens when blood flow to the heart is temporarily reduced. Symptoms often feel like a heart attack—including pain that radiates under the left side of your breast, Dr. Cutler says. Like a heart attack, angina can develop from heart disease. The difference is that symptoms of angina can come and go, and can often be relieved with the right tools, per the Mayo Clinic.

How to treat it: Rest or medications like nitroglycerin can often ease angina pain in the short term, while lifestyle changes or medication to lower blood pressure or cholesterol can help resolve the problem. For sudden angina that won’t go away, call 911 and get to the nearest emergency room, as it could be a sign of a heart attack.

Heart infection

Cardiovascular infections like pericarditis or endocarditis happen when parts of the heart become inflamed. They’re often caused by viral infections like bacteria or pneumonia. You might feel a sharp or stabbing pain around or under your breasts or upper abdomen that gets worse when you lie down, breathe deeply, or cough.

How to treat it: Seek medical attention if you have signs of a heart infection. Depending on the infection and its cause, you may need to take high doses of anti-inflammatory medications to reduce inflammation around your heart or take antibiotics or antifungals to clear the infection, note the National Institutes of Health.

Heart attack

Heart attacks happen when a blood clot in an artery blocks the flow of blood to the heart. “They can cause intense chest pain that radiates to the left side, arm, neck, or jaw,” Dr. Cutler says. You might also get chest pressure, tightness or fatigue, a cold sweat, dizziness, nausea, or shortness of breath, according to the Mayo Clinic.

How to treat it: A heart attack is an emergency that requires immediate medical attention. If you or someone you know is having possible symptoms, call 911 immediately.

Diagnosing pain under your left breast

Figuring out the cause of pain under your left breast will depend on the other symptoms you’re having. “A physical examination for signs of heart, lung, or chest wall disease is very important,” to rule out serious heart or lung problems, Dr. Cutler says. Once those are accounted for, your doctor may order other tests like an EKG, chest X-ray, CT scan, or blood tests.

From there, they can figure out the best treatment to relieve your pain.

When to see a doctor

Pain under your left breast isn’t always cause for concern. Sometimes, the problem will clear up on its own (like in the case of a mild injury). But in other cases, the discomfort could be a sign of a serious problem, says Dr. Cutler. Make sure to reach out to your doctor about rib cage pain if:

• The pain happened after trauma or an injury
• The pain is severe and hasn’t gotten better after 24 to 48 hours
• The pain is accompanied by other concerning symptoms like shortness of breath, dizziness, or nausea