HIV-related opportunistic infections

HIV-related opportunistic infection (OI) risk in people living with HIV increases as the CD4 count declines. Risk also increases in people who are not virologically suppressed, regardless of the CD4 count.

For most people living with HIV with an acute OI, antiretroviral therapy (ART) should be considered within the first 2 weeks of initiation of treatment.

The use of ART among people treated for OIs is complicated by drug interactions, drug toxicity profiles, and immune reconstitution inflammatory syndrome (IRIS). IRIS has been observed most commonly with mycobacterial infections (TB and disseminated Mycobacterium avium complex), but may also develop with other OIs.

Primary and secondary prophylaxis against OIs is essential in the prevention of an initial or recurrent episode of OIs in people living with HIV.

Prophylaxis against many OIs can be discontinued for people who respond to ART and maintain a CD4 count above the recommended threshold for more than 3 months. However, if the CD4 count decreases below that threshold, prophylaxis should be resumed.

HIV-related OIs are infections that can occur as a result of impaired cell-mediated immunity in advanced stages of HIV infection. These illnesses tend to occur most often in people who have untreated HIV infection or who fail to respond to antiretroviral therapy (ART). Tuberculosis, Pneumocystis jirovecii pneumonia, candidiasis, cryptococcosis, toxoplasmosis, cytomegalovirus, Mycobacterium avium complex, coccidioidomycosis, and histoplasmosis infections are some of the HIV-related OIs encountered in clinical practice and are covered in this topic.​[1]National Institutes of Health, Centers for Disease Control and Prevention, HIV Medicine Association, and Infectious Diseases Society of America. Panel on Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV. 2025 [internet publication]. https://clinicalinfo.hiv.gov/en/guidelines/hiv-clinical-guidelines-adult-and-adolescent-opportunistic-infections/whats-new ​ This topic covers HIV-related opportunistic infections in nonpregnant adults. Consult guidelines for management during pregnancy and in children.