You cannot tell if someone has AIDS by looking at them. AIDS is a medical diagnosis based on specific lab results or the presence of certain serious infections, and the only way to confirm it is through HIV testing followed by immune system monitoring. Many people living with HIV, even those whose infection has progressed significantly, show no obvious outward signs. That said, advanced HIV does produce recognizable symptoms and health changes worth understanding.
What Makes HIV Different From AIDS
AIDS is not a separate virus. It is the most advanced stage of an HIV infection, reached when the immune system has been severely damaged. A healthy adult has between 500 and 1,200 CD4 cells per cubic millimeter of blood. These are the immune cells HIV targets and destroys over time. A person with HIV is diagnosed with AIDS when their CD4 count drops below 200, or when they develop one of roughly two dozen serious illnesses known as AIDS-defining conditions.
Without treatment, HIV typically takes years to progress to AIDS. During much of that time, a person may feel perfectly fine and look completely healthy. This is one of the main reasons HIV spreads so effectively: people who don’t know they’re infected can transmit the virus for years before symptoms appear.
Physical Signs of Advanced HIV
When HIV does progress to AIDS, the immune system becomes too weak to fight off infections and cancers that a healthy body would normally control. These “opportunistic” illnesses produce the symptoms most people associate with AIDS, though none of them are unique to HIV infection on their own.
Wasting syndrome is one of the most visible signs. It involves unintentional weight loss of more than 10 percent of body weight, often accompanied by chronic diarrhea, weakness, and fever lasting at least 30 days. A person who weighed 160 pounds losing 16 or more pounds without trying, while also dealing with persistent diarrhea or fever, fits this pattern.
Kaposi sarcoma, a cancer of blood vessel walls, produces distinctive skin lesions. On lighter skin, these appear as pink, red, or purple raised spots. On darker skin, they tend to look dark brown or black. The lesions can appear on the skin, inside the mouth, or on internal organs. While Kaposi sarcoma can occur in people without HIV, it is far more common and aggressive in people with severely weakened immune systems.
Other common AIDS-related conditions include a specific type of pneumonia caused by a fungus, chronic herpes sores lasting longer than a month, severe yeast infections in the throat or lungs, recurrent bacterial pneumonia, and certain types of lymphoma. Tuberculosis is another major AIDS-defining illness and remains one of the leading causes of death in people with advanced HIV worldwide.
Cognitive and Neurological Changes
AIDS can also affect the brain. HIV-associated dementia causes memory loss, difficulty concentrating, trouble speaking clearly, and a gradual decline in coordination and motor skills. Some people develop apathy and lose interest in activities they previously enjoyed. In severe cases, inflammation of the brain and spinal cord membranes (encephalitis) can occur. These cognitive symptoms tend to develop slowly and may initially be mistaken for depression or normal aging, especially in older adults.
Why You Can’t Diagnose AIDS by Appearance
Every symptom listed above can also be caused by conditions that have nothing to do with HIV. Rapid weight loss happens with cancer, thyroid disorders, and digestive diseases. Skin lesions have dozens of causes. Memory problems are common in many neurological conditions. No combination of visible symptoms can reliably confirm or rule out AIDS.
There is also the opposite problem: someone with an AIDS diagnosis may look and feel well, particularly if they have recently started treatment. Antiretroviral therapy can raise CD4 counts and suppress the virus to undetectable levels, even in people who were critically ill. A person who technically met the criteria for AIDS at one point may now appear completely healthy.
The CDC puts it simply: the only way to know someone’s HIV status is through testing.
How HIV Testing Works
Three types of tests detect HIV, each with a different detection window after exposure:
- Nucleic acid tests (NAT) detect the virus itself in the blood and can identify infection 10 to 33 days after exposure. These require a blood draw from a vein and are processed in a lab.
- Antigen/antibody tests look for both viral proteins and the body’s immune response. A lab-based blood draw can detect infection 18 to 45 days after exposure. A finger-prick version takes longer, requiring 18 to 90 days.
- Antibody tests detect only the immune response and work 23 to 90 days after exposure. Most rapid tests and home self-tests fall into this category.
If you’re trying to determine whether someone might have HIV or AIDS, the reality is that no amount of observation can replace a test. A person can carry the virus for years with zero symptoms, and a person with visible illness may have any number of other conditions.
Who Should Get Tested
Current medical guidelines recommend that all adolescents and adults between ages 15 and 65 get screened for HIV at least once, regardless of perceived risk. People at higher risk, such as those with multiple sexual partners, people who inject drugs, or men who have sex with men, benefit from more frequent testing. The CDC suggests annual screening for those at increased risk, and every 3 to 6 months for those at highest risk.
Pregnant individuals should be screened during prenatal care, with repeat testing in the third trimester recommended for those with risk factors or in areas where HIV is more common.
What Happens After an HIV Diagnosis
If someone tests positive for HIV, their doctor will order a CD4 count and a viral load test to determine how far the infection has progressed. A CD4 count above 200 means the person has HIV but not AIDS. A count below 200, or the presence of an AIDS-defining illness, means the infection has reached its most advanced stage.
The distinction matters for treatment urgency but not for treatment itself. Everyone diagnosed with HIV is started on antiretroviral therapy regardless of stage. With consistent treatment, most people with HIV never develop AIDS, and those already diagnosed with AIDS can rebuild their immune systems significantly. Many people on effective treatment reach undetectable viral loads, meaning the virus is suppressed to levels too low to transmit sexually and too low to cause further immune damage.