Updated on October 27, 2026 · Our editorial process
Most people could not point to their spleen if you asked them. It gets none of the attention the heart or liver gets, and you can live without it. Yet it quietly does three jobs that matter every single day: it cleans your blood, it helps you fight infection, and it keeps a reserve of blood cells ready for emergencies.
This guide covers what the spleen is, exactly where it sits, what it does, the signs that something is wrong with it, and what happens if it has to be removed. If you came here with pain under your left ribs, there is a section on that too.
Key takeaways
- The spleen sits in the upper left of your belly, tucked under the lower ribs, behind the stomach and above the left kidney. In a healthy adult you cannot feel it from the outside.
- It filters old and damaged red blood cells out of your blood, makes and stores white blood cells that fight infection, and holds a reserve of platelets and red cells.
- The most common spleen problem is enlargement, usually caused by an infection, liver disease, or a blood disorder. The most dangerous is a rupture after a blow to the abdomen.
- You can live without a spleen, but your risk of certain serious bacterial infections goes up for life, so vaccines and quick treatment of any fever become essential.
What is the spleen?
The spleen is a soft, dark purple organ about the size of your fist. In an adult it is roughly 4 to 5 inches long, 10 to 12 centimeters, and weighs 5 to 7 ounces, about the same as a medium apple. It is the largest organ in your lymphatic system, the network that moves immune cells around the body, but it also plugs directly into your bloodstream. That double role is what makes it unusual.
Inside, the spleen has two kinds of tissue. Red pulp is a dense network of blood-filled channels where old red blood cells are pulled out of circulation and broken down. White pulp is packed with white blood cells and works like a lymph node sitting in the middle of your blood supply, checking everything that flows past for bacteria and other invaders. The Cleveland Clinic describes it simply as a filter for your blood.
Where is the spleen located?
Your spleen is on the left side of your body, in the upper part of the abdomen. Put your left hand flat over your lowest ribs, just below the chest and toward the back, and it is sitting underneath, protected by ribs nine through eleven. It lies directly behind the stomach, above and in front of the left kidney, and just below the diaphragm, the muscle that separates your chest from your belly.
Because the ribs cover it, a normal spleen cannot be felt by pressing on the abdomen. That is a useful fact. If a doctor can feel your spleen during an exam, it has usually grown to at least one and a half times its normal size. The ribs also explain the pain pattern when something goes wrong. Spleen pain is felt high on the left, under the ribs, and because the diaphragm shares a nerve with the shoulder, it can also be felt at the tip of the left shoulder.
People sometimes mix up which side the spleen is on. The liver and gallbladder are on the right. The spleen is on the left, roughly opposite the liver.
What does the spleen do?
The spleen has four main jobs, and it runs them all at the same time.
It filters your blood
Red blood cells live for about 120 days. As they age they become stiff, and the narrow channels of the red pulp catch them and break them down. Iron from the old cells is saved and sent back to the bone marrow to build new ones. The spleen also removes abnormal cells, bits of cell debris, and some bacteria. Your whole blood supply passes through it many times a day.
It fights infection
The white pulp makes and stores lymphocytes, the white blood cells that recognize invaders and produce antibodies. The spleen is especially good at clearing a group of bacteria that wear a sugar coat, known as encapsulated bacteria. These include the germs behind pneumococcal pneumonia and meningitis. This is the reason people without a spleen need specific vaccines, which we cover below.
It stores blood
About a third of your platelets, the cell fragments that form clots, sit in the spleen at any moment, along with a reserve of red blood cells. If you bleed heavily, the spleen contracts and pushes that reserve into circulation. It is a small emergency supply, not a large one, but it helps.
It makes blood cells before birth
In a developing baby, the spleen produces red blood cells. After birth the bone marrow takes over, but in some blood diseases the spleen can switch this job back on, which is one reason it grows large in conditions like thalassemia.
Signs of a spleen problem
A healthy spleen is silent. You notice it only when it enlarges, gets injured, or starts destroying too many blood cells. These are the signs worth knowing.
- Pain or fullness under the left ribs. An enlarged spleen presses on the stomach, so people often feel full after only a few bites. The pain can be a dull ache or a sharper pain that spreads to the left shoulder.
- Tiredness and looking pale. If the spleen becomes overactive and removes healthy red cells, anemia follows. That brings fatigue, breathlessness on stairs, and pale skin.
- Frequent infections. A spleen that is not working well leaves you more open to bacterial infections, especially chest infections.
- Easy bruising or bleeding. An enlarged spleen can trap too many platelets, which makes bleeding gums and bruising more likely.
- Sudden severe left-sided pain after an injury. This can mean a ruptured spleen. If it comes with dizziness, a racing heart, or pain at the left shoulder tip, call emergency services.
The NHS has a clear page on spleen problems and spleen removal if you want the medical detail behind these signs. For a full walk-through of what the pain itself feels like and the causes behind it, see our guide to spleen pain, its causes, and when to see a doctor.
Common spleen problems
Enlarged spleen
Doctors call it splenomegaly, and our full guide to enlarged spleen symptoms, causes, and treatment covers it in depth. It is not a disease in itself but a sign that something else is going on. The usual causes, according to the Mayo Clinic, are viral infections such as mononucleosis, liver disease such as cirrhosis, blood disorders such as sickle cell disease and thalassemia, blood cancers such as leukemia and lymphoma, and parasitic infections such as malaria. Treatment is aimed at the cause, and the spleen usually shrinks back once that is dealt with.
Ruptured spleen
The spleen has a thin capsule and a rich blood supply, so a hard blow to the left side, in a car accident, a fall, or a contact sport, can tear it and cause heavy internal bleeding. An already enlarged spleen tears more easily, which is why people recovering from mono are told to avoid contact sports for several weeks. Treatment ranges from close observation in hospital to surgery to remove the spleen.
Overactive spleen
Sometimes the spleen removes blood cells faster than the marrow can replace them. This is called hypersplenism, and it causes low counts of red cells, white cells, or platelets. It usually happens alongside an enlarged spleen and is treated by treating the underlying condition.
Problems from birth or disease
Some people are born without a working spleen. In sickle cell disease, repeated small blockages damage the spleen over childhood until it stops functioning, a process doctors call autosplenectomy. In both cases the person needs the same precautions as someone whose spleen has been removed.
Some conditions weaken the spleen without removing it, a state doctors call hyposplenism. Sickle cell disease is the best-known cause, and celiac disease and long-term liver disease can also do it, so people with these conditions are sometimes advised to have the same vaccines.
Roughly 1 in 10 people also has a small extra piece of spleen, called an accessory spleen or splenule, usually sitting close to the main one. It causes no symptoms and is normally found by chance on a scan. It matters mainly when the spleen is removed for a blood disorder, because a missed accessory spleen can carry on destroying blood cells, so surgeons look for one during the operation.
Can you live without a spleen?
Yes, and we have a separate guide to life without a spleen that goes through the vaccines, antibiotics, and daily habits in detail. Thousands of people have their spleen removed each year, an operation called a splenectomy, after an injury, because of a blood disorder, or as part of cancer treatment. The liver and bone marrow take over most of the filtering and recycling, and most people feel no day-to-day difference.
What does change is infection risk. Without a spleen you lose your best defense against encapsulated bacteria, and an infection that would be minor in someone else can turn into overwhelming sepsis within hours. The risk is highest in the first two years after removal and in young children, but it never goes away completely. For that reason, people without a spleen are advised to:
- Have the pneumococcal, meningococcal, and Haemophilus influenzae type b vaccines, plus a flu shot every year.
- Take a daily low-dose antibiotic, at least for the first few years and for life in some cases.
- Treat any fever as urgent and get medical help straight away, within hours.
- Carry a card or wear a bracelet saying they have no spleen, and take extra care with travel to malaria areas and with animal bites.
What spleen removal involves
Most splenectomies today are done by keyhole surgery, called laparoscopic surgery, through three or four small cuts in the abdomen under general anesthesia. Open surgery through one larger cut is used for a very large spleen or after a serious injury. According to the NHS, recovery after keyhole surgery usually takes a few weeks, and longer after open surgery.
When the operation is planned, vaccines are given at least two weeks beforehand so the body has time to respond. After an emergency removal, they are usually given about two weeks after surgery.
MedlinePlus has a plain summary of spleen diseases and the precautions that follow removal.
How doctors check your spleen
A spleen check usually starts with a hand on your belly. The doctor presses under your left ribs while you breathe in, because a normal spleen cannot be felt and an enlarged one can. From there, the common tests are a full blood count to look at your red cells, white cells, and platelets, and an ultrasound scan, which shows the spleen's size clearly and takes a few minutes. A CT or MRI scan gives more detail if a cause is not obvious, and blood tests for infections, liver function, and blood disorders help pin it down.
How to keep your spleen healthy
There is no special exercise or supplement for the spleen. What protects it is looking after the things it depends on.
- Protect it from injury. Wear a seat belt, and if you have had mono or a known enlarged spleen, stay out of contact sports until your doctor clears you.
- Look after your liver. Liver disease is one of the most common reasons a spleen enlarges, because blood backs up from the liver into the spleen. Keeping alcohol within sensible limits and keeping your weight in a healthy range protects both organs.
- Stay up to date with vaccines. This matters most for anyone with a damaged or missing spleen, but a yearly flu shot helps everyone's immune system.
- Treat infections properly. Finish courses of antibiotics, and do not ignore a fever that lasts more than a couple of days.
- Eat for your blood. The spleen recycles iron and relies on a steady supply of nutrients to make immune cells. Our guide to the best foods for spleen health covers the practical side, including what to limit if your spleen is already enlarged.
When to see a doctor
Book an appointment if you have ongoing fullness or aching under your left ribs, if you feel full after very small meals, if you are unusually tired or pale, or if you keep getting infections. Go to an emergency department or call emergency services if you have sudden, severe pain in the upper left abdomen, especially after any kind of blow or fall, and if that pain comes with dizziness, a fast heartbeat, pain at the left shoulder tip, or fainting. Those are signs of bleeding from a ruptured spleen.
The bottom line
The spleen is a small organ with an outsized role: it cleans your blood, trains and stores the cells that fight infection, and keeps a reserve of blood cells for emergencies. It sits under your left ribs where you cannot feel it, which is exactly why problems are easy to miss until they show up as fullness, pain, tiredness, or repeated infections. You can live without one, but with extra care. If something feels wrong on your left side, especially after an injury, get it checked rather than waiting it out.
Frequently asked questions
Where is the spleen located in the body?
The spleen is in the upper left part of the abdomen, under the lower ribs, behind the stomach and above the left kidney, just below the diaphragm. In a healthy adult it is protected by the rib cage and cannot be felt from outside.
What does the spleen do?
It filters old and damaged red blood cells out of the blood and recycles their iron, makes and stores white blood cells that fight infection, and keeps a reserve of platelets and red blood cells that it releases if you bleed heavily.
What side is your spleen on?
The left side. The spleen sits under the left ribs, roughly opposite the liver, which is on the right. Pain from the spleen is felt high on the left side of the abdomen and sometimes at the tip of the left shoulder.
Can you live without a spleen?
Yes. The liver and bone marrow take over most of its work. The main change is a higher lifelong risk of certain serious bacterial infections, so people without a spleen need specific vaccines, sometimes daily antibiotics, and same-day medical care for any fever.
What causes an enlarged spleen?
The most common causes are viral infections such as mononucleosis, liver disease such as cirrhosis, blood disorders such as sickle cell disease, blood cancers such as lymphoma and leukemia, and parasitic infections such as malaria. The spleen usually shrinks back once the cause is treated.
Can an enlarged spleen go back to normal size?
Often, yes, once the cause is treated. After mononucleosis the spleen usually returns to its normal size within a few weeks to a couple of months. When the cause is a long-term condition such as cirrhosis or a blood disorder, it may stay enlarged, and treatment then focuses on managing that condition and protecting the spleen from injury.
What does spleen pain feel like?
Usually a dull ache or a feeling of fullness under the left ribs that is worse after eating, sometimes with pain at the left shoulder tip. Sudden, severe pain in that area after a blow or fall, with dizziness or a racing heart, can mean a ruptured spleen and needs emergency care.
Can the spleen grow back after it is removed?
Not as a whole organ. In some people, small pieces of spleen tissue left behind during surgery or scattered by an injury can grow and take on part of its function. This is called splenosis, but it does not restore full protection against infection, so the usual precautions still apply.
Is the spleen part of the digestive system?
No. It sits next to the stomach but it does not help with digestion. The spleen belongs to the lymphatic and immune systems and works on the blood. People sometimes assume it is digestive because an enlarged spleen presses on the stomach and makes you feel full quickly.
