The Spleen: What It Does and What Changes Without It

Where is the spleen?

The spleen sits high in the upper-left abdomen, behind the lower ribs and near the stomach, pancreas and left kidney. In a healthy adult it is usually about the size of a fist. It belongs to both the lymphatic and circulatory systems because it monitors blood while supporting immune responses.

What does the spleen do?

Red pulp and white pulp

The spleen’s red pulp filters blood, removes aging red cells and helps recycle iron. Its white pulp contains immune cells organized around blood vessels, where they can recognize blood-borne threats. The marginal zone between them is especially important for responding to certain bacteria with protective outer capsules.

What changes when the spleen is removed?

A person can live without a spleen. The liver, bone marrow, lymph nodes and other immune tissues continue many essential functions, but they do not completely replace the spleen’s ability to rapidly filter certain organisms from the blood. Surgical absence is called anatomic asplenia. A spleen that is present but does not work effectively is called functional asplenia or hyposplenism.

The increased infection risk is lifelong, even when surgery happened decades earlier and the person feels healthy. The practical goal is preparation: appropriate vaccines, a clear fever plan, prompt evaluation and communication with every healthcare team.

Why can infection become serious quickly?

The spleen is particularly important for clearing encapsulated bacteria—organisms protected by an outer coating that makes them harder for the immune system to capture. Important examples include Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type b. Without normal splenic function, infection can enter the bloodstream and progress rapidly to sepsis.

People with asplenia also need individualized advice about animal bites and scratches because Capnocytophaga bacteria can cause severe infection, and about travel or tick exposure because malaria and babesiosis affect red blood cells.

Building a lifelong prevention plan

Keep vaccines current

U.S. guidance commonly includes pneumococcal, meningococcal ACWY, meningococcal B and Hib vaccination for people with anatomic or functional asplenia, along with routine vaccines such as annual influenza vaccination. Exact products, doses and boosters depend on age, prior vaccines and current CDC guidance. Review the record with a clinician or pharmacist.

Have a written fever plan

A clinician may recommend daily preventive antibiotics for some people, an emergency supply for others, or another plan based on age, time since splenectomy and medical history. The plan should explain whom to call, where to go and whether prescribed standby medication should be taken while urgent care is arranged.

Make asplenia visible

Tell clinicians, dentists and pharmacists that you do not have a functioning spleen. A medical identification bracelet or wallet card can communicate this if you become too ill to explain. Before international travel, ask early about destination-specific vaccines, malaria prevention and access to medical care.

Treat bites promptly

Dog or cat bites—and scratches that break the skin—deserve prompt cleaning and medical advice. A clinician can decide whether preventive antibiotics or other treatment is appropriate.

The spleen, platelets and clotting

The spleen normally stores and removes some platelets. After splenectomy, platelet counts can rise, particularly during the weeks after surgery; in some people the elevation persists. Blood-clot risk depends on the reason for surgery, the platelet count and other health factors. A complete blood count and any treatment decisions should be interpreted by a clinician.

Can food replace what the spleen does?

No diet, food or supplement can replace splenic immune function or restore a removed spleen. Nutritious food can support general health, energy and cardiovascular health, but it cannot substitute for vaccination, antibiotics when prescribed or urgent evaluation of infection.

On The Nutrient, this distinction matters. Eleonora’s food choices are part of her lived experience and the way she cares for her overall health. They are not presented as a replacement for medical prevention or treatment after splenectomy.

Frequently asked questions

Can you live a normal life without a spleen?

Many people live active lives after splenectomy. The difference is that prevention and a rapid response to possible infection remain important for life.

Can the spleen grow back?

A removed spleen does not ordinarily regenerate as a complete organ. Some people have small accessory spleens or residual tissue, but medical testing is needed to determine whether it is functional.

Does asplenia mean you are always sick?

No. Asplenia may cause no daily symptoms. It raises susceptibility to particular serious infections, which is why prevention and prompt care matter even when a person feels well.

Are vaccines needed only once?

Not always. Some series require multiple doses or later boosters. Recommendations change, so review your record against the latest schedule with a clinician or pharmacist.

Sources and further reading

• CDC: Adult Immunization Schedule by Medical Condition
• CDC: Pneumococcal Vaccination
• Preventing infections in children and adults with asplenia
• The spleen in local and systemic regulation of immunity
• Cleveland Clinic: Asplenia

Sources reviewed October 3, 2026. This page provides general education and is not a personal diagnosis or treatment plan.