The most preventable cause of immune deficiency is human immunodeficiency virus (HIV) infection. Medical advances have nearly eliminated contaminated blood as a source of HIV infections. HIV is spread among adults mostly through unprotected sex and among injection drug users through sharing contaminated needles. Preventing the spread of HIV would prevent many deaths from non-Hodgkin lymphoma. Treating HIV with anti-HIV drugs also seems to lower the chance of developing non-Hodgkin lymphoma significantly.

Preventing the spread of the human T-cell leukemia/lymphoma virus (HTLV-1) could have a great impact on non-Hodgkin lymphoma prevention in areas of the world where this virus is common, such as Japan and the Caribbean region. The virus is rare in the United States but seems to be increasing in some areas. The same strategies used to prevent HIV spread could also help control HTLV-1.

The recent discovery of the link between Helicobacter pylori infection and some lymphomas of the stomach offers a potential opportunity for prevention, but the benefit of this strategy has not been proven yet. Most people with H. pylori infection have no symptoms, and some have only mild heartburn. Finding the best way to detect and treat this infection in people without symptoms will require more research.

Some non-Hodgkin lymphomas are caused by treatment of cancers with radiation and chemotherapy or the use of immune system-suppressing drugs to avoid rejection of transplanted organs. Doctors are trying to find ways to treat cancer and organ transplant patients in ways that do not increase the risk of lymphoma as much. But for now, the life-threatening nature of the diseases requiring these treatments still usually outweighs the small risk of developing non-Hodgkin lymphoma many years later.