HIV is a virus that targets the immune system. The signs and symptoms differ depending on a person’s stage of HIV infection.

Around 1.2 million people in the United States are living with HIV, but many are not aware of their status, partly due to a lack of symptoms. An estimated 1 in 7 people with HIV do not know they have it.

When a person first contracts HIV, they may experience a non-specific illness, including a fever and possibly a rash. After this, HIV infection may not cause any symptoms for a decade or more, until it has damaged the immune system enough that the person can develop severe infections.

However, modern medications can prevent HIV from damaging the immune system by controlling the ability of the virus to grow in the human body.

The advent of newly-effective drug regimens means that people with HIV can live long, healthy lives, and few people now develop the advanced stage HIV infection, known as AIDS, when they are under appropriate care.

This article looks at the symptoms of different stages of HIV, how the virus transmits, and possible treatments.

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HIV is a virus that targets the body’s immune system. The virus attaches to, enters, and damages or destroys white blood cells called CD4 T cells. These cells are important for helping the body fight off infections from viruses, bacteria, and fungi.

Without treatment, HIV gradually damages more and more cells, weakening the immune system over a number of years. Eventually, the body is unable to fight off infections.

However, treatments known as antiretroviral therapy reduce the amount of HIV in the blood to very low levels.

When the levels are low enough to be undetectable, the virus no longer damages the immune system and there is virtually no risk of transmitting the virus to other people. This is known as undetectable = untransmittable (U=U).

The symptoms of an HIV infection differ depending on the stage of the infection. Symptoms and progression also differ between individuals.

Without treatment, an HIV infection tends to progress through three stages: acute infection, chronic infection, and stage 3 infection.

People often do not experience symptoms for many years, or until the condition is very advanced. Because of this, a person cannot rely on symptoms to tell if they have HIV. The only way a person can find out their HIV status is by taking a test.

Anyone who thinks they may have the virus should speak with a healthcare provider. Find out how to get tested for HIV in the U.S. here.

Stage 1: Acute HIV infection

Soon after a person contracts HIV, they may develop flu-like symptoms. These symptoms typically appear within 2–4 weeks and may last for several days or weeks.

The symptoms of an acute HIV infection can include:

  • fever
  • fatigue
  • a skin rash that usually does not itch
  • muscle aches
  • night sweats
  • a sore throat
  • swollen glands in the throat, groin, or armpits
  • sores or ulcers in the mouth or genitals
  • nausea, vomiting, or both

This is known as a seroconversion illness. Seroconversion is when the body begins to produce antibodies against the virus. This is the body’s natural response to detecting an infection.

At this stage, the virus replicates rapidly. The person has a large amount of HIV in their blood, and the risk of transmitting the virus to others is high.

Not everyone develops symptoms at this stage. Others experience mild flu-like symptoms that go largely unnoticed. This means that people may contract HIV without knowing it, which makes testing very important.

If a person thinks they may have been exposed to HIV, it is important to talk to a healthcare provider for advice, and to ask them about preventative medication called post-exposure prophylaxis (PEP).

Healthcare providers can order tests to check for HIV. Some tests can detect the virus after 10 days, while others may not detect the infection until 90 days after exposure. People often need to take more than one test for accurate results.

Stage 2: Chronic HIV infection

After the acute phase, HIV continues to reproduce at very low levels in the body, and it continues to damage the immune cells. People typically do not experience symptoms or get sick from the virus during this stage.

This stage is also known as asymptomatic HIV infection or clinical latency.

Without medication, the chronic stage of an HIV infection can last for a decade or more. People can still transmit the virus to others during this time.

Antiretroviral therapy slows or stops the progression of HIV. People who take antiretroviral drugs as prescribed may remain in the chronic HIV stage for life and never develop stage 3 HIV.

Stage 3 HIV

Stage 3 HIV, also known as AIDS, is the most advanced stage of the condition. This occurs when the person’s immune system is badly damaged and can no longer fight off infections.

People who take antiretroviral therapy can maintain a low viral load and may never develop stage 3 HIV. Other factors that affect whether this stage develops include age, genetic factors, and the strain of the virus.

Symptoms of stage 3 HIV can include:

  • weight loss
  • night sweats
  • fever
  • chronic diarrhea
  • a persistent cough
  • skin problems
  • mouth problems
  • regular infections
  • serious illness

A healthcare provider may diagnose stage 3 HIV if a person’s CD4 blood count drops below 200 cells per cubic milliliter (cells/mm3), or if they develop an opportunistic infection.

Opportunistic infections are those that take advantage of a weakened immune system. Common opportunistic infections in the U.S. include:

  • cryptococcal meningitis, a fungal infection
  • herpes, a viral infection
  • salmonella, a bacterial infection
  • candidiasis, a fungal infection
  • toxoplasmosis, a parasitic infection that affects the brain

Without treatment, people with stage 3 HIV typically survive an average of 3 years. People can recover from serious HIV-related infections and diseases and bring HIV under control with treatment.

Some symptoms differ by sex. Read more about HIV in males and HIV in females.

The most common ways people get HIV are anal or vaginal sex or sharing drug injection equipment, such as needles, syringes, or cookers.

A person can contract HIV if damaged tissue or mucous membranes, such as in the genitals, rectum, or mouth, come into contact with fluids that contain the virus.

Only certain body fluids can pass HIV between people. These fluids are:

  • blood
  • semen or preseminal fluid
  • vaginal fluid
  • rectal fluid
  • breast milk

A baby can contract HIV from a mother during pregnancy, childbirth, or breastfeeding. This is less common.

There are many myths about HIV transmission. People do not contract HIV from any of the following:

  • mosquito bites, ticks, or other insects
  • sweat, tears, or saliva
  • hugging, shaking hands, or social kissing
  • sharing bathrooms, food, drinks, or dishes
  • sexual activities, such as touching, that do not involve the exchange of body fluids
  • through the air

Read about the myths and facts of HIV transmission here.

The only way a person can know their HIV status is through taking a test. The Centers for Disease Control and Prevention (CDC) recommend that everyone between 13 and 64 get tested for HIV at least once.

There are three types of test for HIV:

  • Nucleic acid test: This blood test looks for the virus in the blood, and can reveal the person’s viral load. It involves drawing blood from a vein.
  • Antigen/antibody test: This blood test looks for the presence of antigens or antibodies in the blood that can signal an HIV infection. It involves either drawing blood or taking a finger prick.
  • Antibody test: This test looks for HIV antibodies in the blood or oral fluid. This can involve drawing blood from a vein, a finger prick, or an oral swab.

People can get an HIV test in a healthcare clinic or do a self-test at home.

It is not possible to detect HIV immediately after infection. The time between exposure and when a test can produce accurate results is known as the “window period.” This can be between 10 days and 3 months, depending on the individual and the specific test used.

To be sure of an accurate result, a person must take an HIV test after their window period.

If a person thinks they may have been exposed to the virus in the last 72 hours, it is important to talk to a healthcare provider as soon as possible and ask them about post-exposure prophylaxis (PEP), which can be highly effective.

There are many ways HIV-negative people can prevent contracting the virus, and there are many ways that HIV-positive people can avoid transmitting the virus to others.

Ways to prevent HIV transfer include the following:

  • Using condoms correctly when having sex.
  • Never sharing needles, syringes, or other drug injection equipment. If a person does share equipment, disinfecting the equipment with bleach can reduce the risk of HIV and hepatitis. The CDC provides advice about cleaning syringes here.
  • People at risk of contracting HIV can take pre-exposure prophylaxis (PrEP). When taken as prescribed, this method is highly effective at preventing HIV. Truvada and Descovy are two PrEP drugs approved by the Food and Drug Administration (FDA).

People who are HIV-positive can prevent transmitting the virus to others by taking antiretroviral drugs.

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 the virus to other people.

The U.S. Preventive Services Task Force issued new guidelines in 2019, stating that doctors can only recommend PrEP for those with a recent negative HIV test.

HIV is a virus that gradually weakens the immune system by targeting CD4 cells. The signs and symptoms differ depending on which stage of HIV infection a person has.

People can live with HIV for many years without any symptoms. This is why getting tested for HIV is important.

With effective treatment, many people with HIV can live long, healthy and symptom-free lives.