Causes and risk factors of Non-Hodgkin lymphoma (NHL)

For most people with NHL, a cause is never found. But there are factors that are known to increase the risk of developing it.

What are risk factors?

In many cases, experts do not know exactly what causes lymphoma. However, some things may increase the risk of developing it. These are called risk factors.

It is important to remember that having these risk factors does not mean you will get lymphoma. Many people affected by lymphoma do not have any risk factors.

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Some viruses or bacteria can increase the risk of developing non-Hodgkin lymphoma (NHL).

An infection called helicobacter pylori can sometimes cause a type of NHL called MALT lymphoma.

The Epstein Barr virus (EBV), which causes glandular fever, may slightly increase the risk of developing NHL.

Both infections are very common in the UK. But most people who have had these infections will not develop lymphoma.

Lymphoma is not infectious and cannot be passed on to other people.

A weakened immune system

If the body's immune system is weak, the risk of developing lymphoma may be higher.

Conditions such as HIV can weaken the immune system. Drugs called immunosuppressants also cause this. Some people need this type of drug after an organ transplant or to treat auto-immune disease.

Auto-immune disease

Auto-immune diseases develop when the immune system attacks healthy body tissue by mistake. Several auto-immune diseases can increase the risk of lymphoma. These include conditions called:

  • rheumatoid arthritis
  • Sjogren’s syndrome
  • systemic lupus erythematosus.

Doctors do not fully understand why these diseases increase the risk of developing lymphoma. It may be because of the diseases themselves, or because of the treatments used to control them.

A previous cancer

NHL is slightly more common in people who have had cancer before. This may be because of the cancer or because of the cancer treatments. Treatment with radiotherapy, or with some chemotherapy drugs, can increase the risk of developing NHL many years later. But the risk is small compared to the benefit of having the treatment in the first place.

Having a close relative with non-Hodgkin lymphoma (NHL)

Having a parent, brother or sister with NHL may mean you have a higher risk of developing it. But the risk of developing NHL is still low, with a lifetime risk of about 3 in 100 (3%). The lifetime risk for people who do not have a close relative with NHL is about 2 in 100 (2%).

About our information

  • References

    Below is a sample of the sources used in our non-Hodgkin lymphoma (NHL) information. If you would like more information about the sources we use, please contact us at

    National Institute for Health and Care Excellence (NICE). Guideline NG46. Haematological cancers: improving outcomes. 2016.

    National Institute for Health and Care Excellence (NICE). Guideline NG52. Non-Hodgkin’s lymphoma: diagnosis and management. 2016.

    Treleaven, et al. Guidelines on the use of irradiated blood components prepared by the British Committee for Standards in Haematology blood transfusion task force. British Journal of Haematology. 2011.

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editors, Dr Anne Parker, Consultant Haematologist; and Professor Rajnish Gupta, Macmillan Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.