HIV is a virus that gradually weakens the immune system. Without treatment, it progresses over time through three stages. The timing depends on many factors, including medications, age, and overall health.

HIV targets white blood cells called CD4 T cells that help protect the body from infection.

By killing these cells, HIV progressively weakens the body’s defenses against infection and illness, leading to complications that can be fatal — unless a person receives effective, ongoing treatment.

Antiretroviral therapy can prevent HIV from progressing, especially when a person starts taking it early. People with HIV who receive this treatment can live long, healthy lives, with life expectancies comparable to those of people without HIV.

This article looks at the timeline of HIV symptoms, the stages of the infection, and the outlook. We also describe how to prevent HIV from progressing.

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When a person contracts HIV and does not receive treatment, the infection progresses through three stages.

For anyone who may have been exposed to HIV, it is important to talk to a healthcare provider for advice and ask them about preventive therapy called post-exposure prophylaxis (PEP).

People at risk of exposure to HIV can take pre-exposure prophylaxis (PrEP), on a regular basis to prevent the infection from taking hold, even if exposure occurs.

Stage 1: Acute HIV infection

After a person comes into contact with HIV, the virus replicates quickly, and the blood contains high levels of the virus. At this time, it can easily transmit to others — through blood, semen and preseminal fluids, rectal fluid, vaginal fluid, and breast milk.

Within 2–4 weeks of exposure to the virus, some people develop a nonspecific syndrome with a fever and other flu-like symptoms. This may last for several days or weeks.

Not everyone experiences these symptoms, however. If a person does not undergo testing, it is possible for HIV to progress without any indication that it is in the body.

The flu-like symptoms of a stage 1 HIV infection may include:

  • a fever
  • muscle or joint pain
  • tiredness
  • night sweats
  • skin rashes
  • ulcers in the mouth
  • a sore throat
  • swollen glands
  • nausea or vomiting

These symptoms are collectively known as a seroconversion illness. They represent the body’s natural response to an infection as it attempts to kill off the virus. However, the human body cannot completely remove this virus once it is present.

At this stage, the virus replicates using the body’s CD4 T cells and spreads throughout the body. In doing so, it destroys CD4 T cells.

Eventually, this process stabilizes. The immune system reduces the number of viral particles, and levels of CD4 T cells may rise. However, the number of these cells may not return to its original level.

Stage 2: Chronic HIV infection

After the acute stage has ended — and if the person has not received treatment — the virus remains active, reproducing at very low levels but continuing to damage immune cells.

At this stage, there are usually no symptoms or very mild ones. This is why doctors sometimes call stage 2 “asymptomatic HIV infection” or “clinical latency.” The virus can still pass to others during this stage, even if it causes no symptoms.

Without treatment, this stage can last for 10 years or more before the person develops stage 3 HIV.

However, modern antiretroviral medications can stop the infection from progressing. These drugs greatly reduce the amount of HIV in the body, the viral load, to very low levels.

When the viral load is so low that tests cannot detect it, HIV can no longer damage the immune system or transmit to other people. Some people refer to this as “undetectable equals untransmittable” or “U=U.”

A person with stage 2 HIV who takes effective antiretroviral therapy may never develop stage 3 HIV.

Stage 3 HIV

Stage 3 HIV, also known as AIDS, is the most advanced stage. It occurs when the immune system is damaged to the extent that it can no longer fight off infections.

Taking antiretroviral drugs keeps the immune system strong enough to prevent HIV from progressing to this stage.

Without treatment, the viral load continues to increase and the CD4 cell count continues to drop. A person will receive a diagnosis of stage 3 HIV if their CD4 cell count drops under 200 cells per cubic milliliter or if they develop an opportunistic infection.

Symptoms at this stage vary greatly, as they tend to stem from specific opportunistic infections.

Symptoms of stage 3 HIV can include:

  • night sweats
  • a fever
  • a persistent cough
  • problems affecting the skin, mouth, or both
  • regular infections
  • chronic diarrhea
  • weight loss

Due to modern treatments, opportunistic infections are increasingly less prevalent. There are many types, but some of the most common opportunistic infections in the United States are:

People can recover from serious HIV-related infections and diseases and bring HIV under control with treatment. Treatments for opportunistic infections include antivirals, antibiotics, and antifungals.

Learn more about complications of HIV here.

The most effective way is to take antiretroviral medication as soon as possible and to do so consistently as prescribed.

Antiretroviral therapy keeps the immune system healthy and reduces the risk of transmitting the virus to virtually zero.

The sooner a person receives a diagnosis, the sooner they can begin treatment. Early treatment can improve the person’s outlook and lower the risk of the virus passing on to others.

Antiretroviral therapy

Antiretroviral therapy keeps the immune system healthy and prevents the virus from transmitting. It benefits a person regardless of the stage of HIV.

Antiretroviral therapy:

  • suppresses viral activity
  • increases the person’s immunity and lifespan
  • reduces the chances of the virus transmitting

Taking antiretroviral therapy reduces the amount of HIV in the blood to very low or undetectable levels. In most people using antiretroviral drugs, the virus is under control within 6 months.

Once the viral load is undetectable, there is virtually no risk of transmitting HIV to other people.

A doctor may adapt the combination of drugs for the individual. Taking the medication consistently as prescribed makes it more effective and reduces the chances of the virus developing resistance to the treatment.

PEP

If a person was recently exposed to the virus, they can prevent it from taking hold using PEP. This is an emergency option.

PEP is most effective when a person takes it as soon as they suspect exposure to HIV and within 72 hours. When a person does this, PEP can prevent HIV.

The World Health Organization (WHO) estimate that when people take it correctly, the 28-day course of PEP reduces the risk of HIV infection by over 80%.

Lifestyle factors

Certain lifestyle factors can play a role in the progression of HIV. A person can adopt strategies to boost their immune system, including:

  • Avoiding infections: Take steps to protect against infections and illnesses, and get regular vaccinations, if the doctor recommends it.
  • Reducing stress: Stress weakens the immune system and increases the risk of developing other illnesses and opportunistic infections.
  • Using condoms during intercourse: Condoms protect people with HIV from other sexually transmitted infections that can further weaken their immunity.
  • Exercising regularly: This brings many benefits, including a lower risk of heart disease, increased energy, improved circulation and lung capacity, better sleep, and less stress.
  • Eating a healthful diet: Maintaining a balanced diet with a low alcohol intake helps boost the immune system and ward off infections. Nutritious food can also help the treatment work properly.
  • Quitting smoking: People with HIV who smoke are more likely to develop infections such as candidiasis and pneumonia, as well as illnesses such as certain cancers, heart disease, and chronic obstructive pulmonary disease.

Other factors that affect the progression

Some of these are not under a person’s control. Additional factors that can play a role in HIV progression include:

  • age
  • genetics
  • the HIV subtype
  • overall health before the infection
  • the presence of other infections

For a person with HIV, the outlook largely depends on whether they have consistent access to treatment and are taking it as prescribed.

If a person with HIV receives consistent antiretroviral therapy before the infection advances, they can live a long, healthy life, with a life expectancy comparable to that of someone without HIV.

Without treatment, a person may develop stage 3 HIV 2–15 years after contracting the infection. The life expectancy after a stage 3 HIV diagnosis is 3 years.

However, with effective medication, many people never develop stage 3 HIV, and the incidence of opportunistic infections is much lower than it was in the past.

Learn how to receive HIV testing in the U.S. here.