Medically Reviewed by Dr. Abhilasha S , Pediatric Hemato Oncologist
Written by KIE Editorial Contributors
3.5 min read | Published On: 08-10-2025
Lymphocytosis means that your blood has more lymphocytes than usual. Lymphocytes are white blood cells. They help the body fight off infections. When these cells go up quickly, it usually means your immune system is working to protect you. Adults usually have lymphocytosis if they have over 4,000 lymphocytes in each microliter of blood. Most of the time, this happens because of short illnesses. Sometimes, it can be a sign of a more serious problem, like blood cancer or an ongoing disease.
Lymphocytosis happens often. It can affect people in these situations:
Most people get lymphocytosis because they are fighting off germs. Viruses often cause this, including:
Some bacterial illnesses, like whooping cough, and certain parasites can also cause higher levels.
Sometimes high lymphocytes mean there is cancer in the blood or lymph system:
Other things that can cause high lymphocyte counts are:
Most people do not feel any symptoms just because their lymphocyte count is high. Instead, symptoms come from the illness causing the problem. These symptoms can include:
Many times, lymphocytosis is found when the doctor does a blood test for another reason.
Doctors check for lymphocytosis by:
You might see a blood specialist if the reason for lymphocytosis is not clear.
The treatment depends on what is causing the high lymphocyte count:
Most people get better once the problem is treated. It is important to have regular check-ups to make sure the blood is back to normal and to catch any issues early.
You might not be able to prevent lymphocytosis, but the chance of getting it can be lowered by:
Get in Touch with a Doctor
Yes, in many cases, lymphocytosis resolves naturally once the underlying infection or inflammation improves. However, if it persists for a long time, it’s important to see a doctor for further evaluation.
No, most cases of lymphocytosis are caused by temporary infections, not cancer. Only in a few cases does it signal a blood or lymphatic cancer, such as leukemia or lymphoma.
If you experience symptoms like night sweats, unexplained weight loss, fever, or swollen lymph nodes for an extended period, you should consult a doctor. These signs could indicate a more serious condition.
Doctors typically detect lymphocytosis during a routine blood test known as a complete blood count (CBC). If the results show elevated lymphocytes, additional tests may be recommended to identify the cause.
You should start by visiting a general physician. If the cause appears complex or blood-related, you may be referred to a hematologist, a doctor who specializes in blood disorders.
1099
