AIDS (acquired immunodeficiency syndrome) is the most advanced stage of HIV infection, diagnosed when the immune system has been severely damaged. The hallmark is a drop in CD4 immune cells to 200 or fewer per cubic millimeter of blood, compared to the normal range of 500 to 1,500. At this stage, the body becomes vulnerable to infections and conditions that a healthy immune system would normally fight off easily. These “opportunistic” infections and their symptoms are, in practical terms, the symptoms of AIDS.
How AIDS Differs From Earlier HIV Stages
HIV infection progresses through stages. Most people experience a brief flu-like illness within a few weeks of infection, then enter a long period where the virus is active but produces few or no symptoms. Without treatment, this chronic phase typically advances to AIDS in about 10 years, though it can happen faster in some people.
During those years, HIV gradually destroys CD4 cells, which coordinate your immune response. Once that count falls below 200, or you develop certain specific infections or cancers, the diagnosis shifts to AIDS. The symptoms at this stage are largely driven by what your weakened immune system can no longer prevent.
General Symptoms of Advanced HIV/AIDS
Before specific infections take hold, many people with AIDS experience a pattern of worsening general symptoms:
- Rapid, unexplained weight loss. Wasting syndrome is defined as losing more than 10 percent of your body weight, combined with diarrhea, weakness, or fever lasting at least 30 days. For someone who weighs 160 pounds, that means dropping 16 or more pounds without trying.
- Recurring fevers and drenching night sweats. These often come and go over weeks or months and may not be tied to an obvious infection.
- Extreme, persistent fatigue. Not the kind that improves with rest, but a deep exhaustion that interferes with daily life.
- Swollen lymph nodes. Lymph nodes in at least two areas of the body, such as the neck, armpits, or groin, may stay enlarged for three months or longer. This condition, called persistent generalized lymphadenopathy, can begin in earlier stages of HIV but often continues into AIDS.
- Prolonged diarrhea. Loose stools lasting more than two weeks are common and can be caused by the virus itself or by infections that exploit the weakened gut.
Opportunistic Infections and Their Symptoms
The infections that define AIDS are called “opportunistic” because they take advantage of a compromised immune system. Each one produces its own set of symptoms, and a person with AIDS may deal with more than one at a time.
Pneumocystis Pneumonia (PCP)
PCP is a fungal lung infection and one of the most common AIDS-defining illnesses. It causes a dry cough, shortness of breath (especially with physical activity), fever, and chest tightness. Symptoms tend to develop gradually over days to weeks rather than hitting all at once. Before effective HIV treatment existed, PCP was often the first sign that someone had AIDS.
Oral and Esophageal Thrush
Candidiasis, commonly known as thrush, is a fungal infection that produces white patches on the tongue, inner cheeks, and roof of the mouth. When it spreads to the esophagus, it causes pain or difficulty swallowing and a feeling that food is stuck in the chest. Thrush in the lungs or airway can cause coughing and breathing difficulties. Vaginal candidiasis is also more frequent and harder to treat in women with AIDS.
Tuberculosis
Tuberculosis (TB) is a bacterial infection that primarily attacks the lungs but can also affect the kidneys, brain, skin, lymph nodes, and eyes. Symptoms include a persistent cough (sometimes with blood), chest pain, fever, night sweats, and weight loss. TB is the leading cause of death globally among people living with HIV, partly because it can occur at higher CD4 counts than many other opportunistic infections.
Toxoplasmosis
This parasitic infection most commonly affects the brain in people with AIDS. Symptoms include headaches, confusion, fever, seizures, and problems with coordination, speech, or vision. It typically reactivates from a dormant infection that a healthy immune system had been keeping in check for years.
Herpes Simplex Infections
While herpes simplex is common in the general population, in people with AIDS it can cause severe, long-lasting outbreaks. These go beyond typical cold sores or genital sores, potentially spreading to the eyes, throat, esophagus, or brain. Herpes-related brain inflammation can cause confusion, seizures, and personality changes.
Chronic Salmonella Infection
Salmonella bacteria cause intestinal illness in anyone, but in people with AIDS, the infection can become recurrent or spread into the bloodstream. Symptoms include persistent diarrhea, fever, abdominal cramps, nausea, and vomiting that keep coming back rather than resolving within a few days as they would in a healthy person.
Skin and Cancer-Related Symptoms
Kaposi sarcoma is a cancer that was rare before the AIDS epidemic and remains one of the most recognizable signs of advanced HIV. It produces dark purple, red, or brown lesions on the skin, often on the legs, face, or inside the mouth. These patches are usually painless but can cause swelling if they block lymph drainage. Kaposi sarcoma can also develop in the lungs or digestive tract, causing breathing problems or internal bleeding.
Other cancers that occur more frequently with AIDS include lymphoma (which can cause swollen lymph nodes, fever, weight loss, and night sweats) and invasive cervical cancer in women. Skin problems in general become more severe and widespread: rashes, sores that heal slowly, and outbreaks of shingles that cover larger areas than they would in someone with a functional immune system.
Neurological Symptoms
HIV itself can damage the brain and nervous system, not just the infections it allows in. As AIDS progresses, some people develop memory problems, difficulty concentrating, confusion, and personality changes. Numbness, tingling, or burning pain in the hands and feet is also common, caused by nerve damage from the virus or from the effects of long-term immune suppression. In severe cases, people may have trouble walking, experience vision changes, or develop significant cognitive decline.
Why Early Detection Changes the Picture
Nearly all of these symptoms are preventable. Modern antiretroviral treatment keeps the virus suppressed, allows CD4 counts to recover, and stops progression to AIDS. People who start treatment early and take it consistently have life expectancies approaching those of the general population. The symptoms described here are what happens when HIV goes undiagnosed or untreated for years, which is why routine HIV testing remains so important. If you’ve had a potential exposure or haven’t been tested recently, a simple blood or saliva test can detect HIV long before any of these complications develop.