The Most Dangerous Complications of HIV and AIDS

Health Line

10-07-2025

Key takeaways
HIV weakens the immune system, making individuals susceptible to opportunistic infections (OIs), which can be life-threatening if the number of CD4 cells drops below 200 cells per cubic millimeter.
Common OIs associated with HIV include candidiasis, pneumonia, and herpes, as well as certain cancers such as Kaposi's sarcoma and lymphoma can also occur.
Following a prescribed drug regimen, getting vaccinated, practicing safe sex, and adopting healthy habits can prevent OIs, significantly improving the life expectancy and quality of life for people living with HIV.
Living with HIV can result in a weakened immune system. This makes the body more susceptible to a host of illnesses. Over time, HIV attacks the body's CD4 cells.
These cells play a critical role in maintaining a healthy immune system. People living with HIV can proactively reduce the likelihood of developing common, life-threatening illnesses by taking their prescribed daily medications and practicing healthy living habits.
What are HIV-related opportunistic infections?
Opportunistic infections (OIs) capitalize on weakened immune systems. In general, complications of HIV don't occur if the body's CD4 count is higher than 500 cells per cubic millimeter. Most life-threatening complications occur when the CD4 count drops below 200 cells per cubic millimeter.
OI illnesses may have little to no significant impact on a person with a healthy immune system. However, they can cause devastating effects for people living with HIV. OIs typically present when the CD4 count drops below 200 cells per cubic millimeter. They are considered stage 3 HIV (or AIDS-defining) conditions.
In general, a person living with HIV will not present with OIs if their CD4 count is above 500 cells per cubic millimeter.
The following 20 OIs have been defined by the Centers for Disease Control and Prevention as stage 3 HIV (or AIDS-defining) illnesses.
Infections common with HIV
Candidiasis. This is a common fungal infection that's also known as thrush. It can be treated with antifungal medications after a simple visual examination.
Coccidioidomycosis. This common fungal infection can lead to pneumonia if left untreated.
Cryptococcosis. This fungal infection often enters through the lungs. It can quickly spread to the brain, often leading to cryptococcal meningitis. Left untreated, this fungal infection is often fatal.
Cryptosporidiosis. This diarrheal disease often becomes chronic. It's characterized by severe diarrhea and abdominal cramping.
Cytomegalovirus. This common global virus affects most adults during their lifetime. It often presents with eye or gastrointestinal infections.
HIV-related encephalopathy. This is often referred to as HIV-related dementia. It can be defined as a degenerative brain condition that affects people with CD4 counts of less than 100.
Herpes simplex (chronic) and herpes zoster. Herpes simplex produces red, painful sores that appear on the mouth or genital area. Herpes zoster, or shingles, presents with painful blisters on skin surfaces. While there is no cure for either, medications are available to alleviate some symptoms.
Histoplasmosis. This environmental fungal infection is commonly treated with antibiotics.
Isosporiasis. This is a parasitic fungus. It develops when people drink or come into contact with contaminated food and water sources. It's currently treated with antiparasitic drugs.
Mycobacterium avium complex. This is a type of bacterial infection. It often presents in people with severely compromised immune systems (CD4 cell counts of less than 50). If these bacteria enter the bloodstream, it often results in death.
Pneumocystis carinii pneumonia (PCP). This OI is currently the leading cause of death in people living with HIV. Careful monitoring and antibiotic therapies are currently used to treat the person following diagnosis.
Chronic pneumonia. Pneumonia is an infection in one or both lungs. It can be caused by bacteria, viruses, or fungi.
Progressive multifocal leukoencephalopathy (PML). This neurological condition often affects people with CD4 cell counts below 200. While there is no current treatment for this disease, some response has been shown with antiretroviral therapies.
Toxoplasmosis. This parasitic infection commonly strikes people with CD4 cell counts below 200. Prophylaxis treatments are used as a preventive measure for people posting low CD4 cell counts.
Tuberculosis. This disease is most common in low-income areas of the world. It can be successfully treated in most cases if caught early.
Wasting syndrome (HIV-related). This OI causes a total weight loss of more than 10 percent of your normal body weight. Treatment involves dietary management and continued antiretroviral therapy.
Kaposi's sarcoma. This form of cancer often presents with either oral lesions or lesions covering the skin surfaces. Current treatments include radiation and chemotherapy to shrink the tumors. Antiretroviral therapy is also used to boost the body's CD4 cell count.
Lymphoma. A variety of cancers frequently present in people living with HIV. Treatment will vary based upon the person's cancer type and health condition.
Cervical cancer. Women living with HIV are at greater risk of developing cervical cancer. An impaired immune system presents challenges associated with treating this form of cancer.
Cancers common with HIV
If a person presents with one or more OIs, the disease will likely be categorized as stage 3 HIV (or AIDS), regardless of the person's current CD4 cell count. OIs are currently the leading cause of death for people living with HIV. However, antiretroviral therapies (HAART) and prophylaxis have shown promise in preventing these diseases, when taken as directed.
Staying healthy with HIV
Doctor-prescribed drug regimens and healthy daily living habits can greatly improve life expectancy as well as quality of life for people living with HIV. People living with HIV can proactively avoid many OIs by following these tips:
Follow a daily drug regimen that includes both antiretroviral therapies and prophylaxes (medications used to prevent disease).
Get vaccinated. Ask your doctor which vaccines you may need.
Use condoms consistently and correctly to avoid exposure to sexually transmitted infections.
Avoid illicit drug use and needle sharing.
Take extra precautions when working in high-exposure areas, such as day-care centers, prisons, healthcare facilities, and homeless centers.
Avoid raw or undercooked products and unpasteurized dairy products.
Wash your hands frequently when preparing foods.
Drink filtered water.