What Does Your Spleen Do?

The spleen is a fist-sized organ tucked under your rib cage on the left side of your abdomen. It filters your blood, removes old or damaged red blood cells, recycles iron, and stores platelets. It also helps your immune system fight certain infections by producing white blood cells. While you can live without it, the spleen plays an important role in your blood health and immune defense.

What does your spleen do exactly?

The spleen has two main types of tissue that do different jobs. The red pulp filters blood. It removes old red blood cells and recycles the iron from them. It also stores about one-third of the body’s platelets, which are needed for clotting. When you bleed, the spleen releases those platelets into the bloodstream.

The white pulp is part of your immune system. It makes white blood cells called lymphocytes. These cells recognize and attack bacteria, viruses, and other invaders. The spleen also filters out germs that travel through the blood. It acts like a checkpoint, catching pathogens before they spread.

In addition, the spleen can act as a reservoir for extra blood. If you lose blood suddenly, the spleen can contract and push stored red blood cells into circulation. This is a backup system, not something the body relies on every day.

Where is your spleen located?

Your spleen sits in the upper left part of your abdomen, behind your stomach and just below your diaphragm. The lower ribs cover and protect it. In a healthy adult, the spleen is about the size of a fist and weighs roughly 150 to 200 grams. You cannot normally feel it by pressing on your belly. If you can feel a firm lump under the left ribs, the spleen is likely enlarged and should be evaluated by a doctor.

What happens when your spleen is enlarged?

Splenomegaly is the medical term for an enlarged spleen. Many conditions can cause it. Infections such as mononucleosis (caused by the Epstein-Barr virus) are a common cause in younger adults. Liver diseases like cirrhosis, blood disorders like sickle cell disease, and some cancers such as leukemia or lymphoma can also enlarge the spleen.

An enlarged spleen may not cause symptoms right away. When symptoms appear, they include a feeling of fullness after eating only a small amount, discomfort or pain in the upper left abdomen, and pain that spreads to the left shoulder. The biggest risk with an enlarged spleen is rupture. A spleen that is enlarged is more fragile. A blow to the abdomen or even a strong cough can tear it. A ruptured spleen causes internal bleeding and is a medical emergency. Anyone with an enlarged spleen should avoid contact sports.

Diagnosis is usually made with a physical exam and imaging tests like ultrasound or CT scan. Treatment depends on the cause. Sometimes treating the underlying condition shrinks the spleen. If the spleen is severely enlarged or causing complications, doctors may recommend removing it.

Can you live without a spleen?

Yes, you can live without a spleen. The procedure to remove it is called a splenectomy. People may need one because of trauma (ruptured spleen), a blood disorder (such as hereditary spherocytosis), or an enlarged spleen that does not respond to treatment. The liver and lymph nodes take over some of the spleen’s filtering and immune work.

However, living without a spleen has serious implications. The spleen is important for fighting infections caused by encapsulated bacteria — especially pneumococcus, meningococcus, and Haemophilus influenzae type b (Hib). Without a spleen, the risk of severe bacterial infections, particularly sepsis, is higher, especially in the first few years after removal. For this reason, doctors recommend that people without a spleen get vaccinated against these bacteria and take daily antibiotics if advised. Any fever in a person without a spleen should be taken seriously and evaluated quickly.

Vaccination timing matters. Ideally, vaccines are given at least two weeks before elective splenectomy. In an emergency removal, vaccines can be given about two weeks after surgery. Some people also carry a supply of emergency antibiotics to take at the first sign of infection.

How can you keep your spleen healthy?

There is no special diet or supplement that directly improves spleen function. The spleen is not like the liver or kidneys in that way. A general healthy lifestyle — balanced diet, regular exercise, not smoking, limiting alcohol — supports your whole body, including your spleen. If you have a condition that affects the spleen, such as liver disease or an infection, following your doctor’s recommendations is the most important step.

One practical way to protect your spleen is to avoid abdominal injury. Wear a seatbelt in the car. If you play contact sports, use proper protective gear. The spleen is well-protected by the ribs, but a strong impact can still damage it. Another measure is to treat infections promptly. An untreated infection can lead to an enlarged spleen and other complications.

Avoiding activities that increase your risk of infection, especially if you have a weakened immune system or no spleen, is also sensible. This includes careful food preparation to avoid foodborne illnesses and staying up to date on vaccines.

When should you see a doctor about your spleen?

You should see a doctor if you have persistent pain or discomfort in the upper left side of your abdomen, especially if it is accompanied by a fever or unexplained weight loss. Pain that spreads to your left shoulder could mean the spleen is irritated or leaking blood. See a doctor right away for this.

Other reasons to seek medical attention include being diagnosed with a condition known to affect the spleen, such as mononucleosis, and having new symptoms like easy bruising or bleeding, frequent infections, or feeling full quickly when eating. If you have a known enlarged spleen, avoid contact sports and talk to your doctor about activity restrictions. If you do not have a spleen, any fever should prompt a medical visit.

Can your spleen grow back?

In rare cases, small pieces of spleen tissue can regrow after removal if they are accidentally left behind during surgery. This is called splenosis. The regrown tissue may take over some function, but it is usually not enough to provide full immune protection. Routine imaging may detect these nodules years later, but they rarely cause problems. Do not rely on regrowth to restore your immunity — follow your doctor’s infection prevention plan if you have had a splenectomy.