HIV is a virus that targets the immune system. It damages and destroys white blood cells called CD4 T cells. Without treatment, HIV can progress to an advanced stage called stage 3 HIV, or AIDS.

The World Health Organization (WHO) estimates there were nearly 39 million people living with HIV worldwide by the end of 2022. In the United States, there were 1.2 million people living with HIV at the end of 2021.

HIV is a serious medical condition that damages the immune system. If left untreated, the virus can progress through three stages that may seriously impair a person’s quality and duration of life.

That said, due to medical advances, people with HIV who receive appropriate treatment rarely develop stage 3 HIV, or AIDS. They can manage their condition and live long, healthy lives.

As of 2022, 76% of people with HIV were receiving antiretroviral therapy.

AIDS-related deaths have also significantly decreased by 51% since 2010.

This article explores HIV and AIDS, including the symptoms, causes, and treatments.

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HIV is a virus that attacks the body’s white blood cells. White blood cells circulate around the body to detect infection and faults in other cells.

HIV targets and infiltrates CD4 cells, a type of T cell. The virus uses these cells to create more copies of the virus.

In doing so, HIV destroys the cells and reduces the body’s ability to combat other infections and diseases. This increases the risk and severity of opportunistic infections and some types of cancer.

What are the stages of HIV?

HIV that is left untreated typically develops in three stages:

  • Stage 1, acute infection: This is when people have large amounts of HIV in the blood and the body begins producing antibodies to try and kill the virus. People typically develop flu-like symptoms 2–4 weeks after contracting HIV, which may last a few weeks. This stage is when HIV is the most transmissible to other people.
  • Stage 2, chronic infection: HIV is still active and reproducing in the body but at a slower rate. Some people may not have symptoms, but the virus is still transmissible. This stage may last 10 years or more without treatment. If treatment begins, the virus may never progress to stage 3.
  • Stage 3 HIV: This is the most advanced stage of HIV, also known as AIDS. It happens when the body can no longer fight off the infection. The survival rate is around 3 years without treatment.

Learn more about the stages of HIV here.

Stage 3 HIV, also called AIDS, is the most advanced stage of HIV. It typically happens if a person does not receive treatment.

Doctors diagnose it when a person’s CD4 blood count contains fewer than 200 cells per cubic millimeter, or if they have opportunistic infections.

The chances of HIV progressing to stage 3 vary for each person and depend on many factors, such as:

  • the person’s age
  • the body’s ability to defend against HIV
  • accessibility of quality healthcare
  • the presence of other infections
  • a person’s genetic resistance to certain strains of HIV
  • the strain of HIV, as some are drug-resistant

Learn the difference between HIV and AIDS here.

HIV and AIDS resources

For more in-depth information and resources on HIV and AIDS, visit our dedicated hub.

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HIV is transmitted when bodily fluids containing the virus are shared between people, including:

  • blood
  • semen
  • pre-seminal fluid
  • vaginal fluids
  • rectal fluids
  • breast milk

The virus cannot be transmitted through saliva. A person cannot contract HIV through open-mouthed kissing, for example.

HIV can be transmitted through:

  • anal or vaginal intercourse
  • sharing needles, such as for tattooing or injecting drugs
  • pregnancy
  • breastfeeding

Transmission typically occurs when people do not use barrier protection during intercourse, such as a condom. It may also happen if people with known risk factors are not taking preexposure prophylaxis (PrEP). PrEP is a treatment that aims to prevent HIV transmission.

In extremely rare cases, HIV may be transmitted through blood transfusions.

Undetectable = untransmittable

HIV can only be transmitted through fluids that contain a certain amount of the virus. If a person has undetectable levels of HIV, the virus cannot be sexually transmitted to another person.

HIV is considered undetectable when the amount of the virus in the body is so low that a blood test cannot identify it. Some people use a shorthand to refer to the fact that undetectable levels of HIV are untransmittable: U=U.

When the virus is undetectable, there’s effectively no risk of sexual transmission. Risk reduction is still unknown for sharing injection drug equipment. During pregnancy, the risk is 1% or less.

However, a person with undetectable levels still has HIV, so it is crucial that they regularly monitor their levels with blood tests and carefully follow their recommended treatment plan.

Learn more about the early detection of HIV here.

Symptoms of HIV depend on the stage of the virus.

Early symptoms of HIV

During stage 1, some people may have no symptoms for months or even years after contracting the virus. This may be why 13% of people with HIV in the United States do not know they have it.

That said, two-thirds of people with HIV develop flu-like symptoms 2–4 weeks after contracting the virus, such as:

These symptoms are collectively called “acute retroviral syndrome.” They result from the immune system fighting off the infection.

If people experience these symptoms and think they may have come into contact with HIV, they should get tested.

Some symptoms of HIV may also vary for males and females.

Learn more about the early symptoms of HIV here.

Asymptomatic HIV

During stage 2, people may not have any HIV symptoms, sometimes for years.

However, the virus continues to develop and damage the immune system and organs. Without treatment, this slow process may continue for 10 years or longer, or progress faster.

Taking antiretrovirals can stop this process and suppress the virus completely.

Late stage HIV

If a person with HIV does not receive effective treatment, the virus weakens the body’s ability to fight infection, exposing it to serious illnesses.

Symptoms of stage 3 HIV include:

  • blurred vision
  • dry cough
  • night sweats
  • white spots on the tongue or mouth
  • shortness of breath, which is called dyspnea
  • swollen glands lasting for weeks
  • diarrhea, which is usually persistent and chronic
  • a fever of over 100°F (37°C) that lasts for weeks
  • continuous fatigue
  • unintentional weight loss

A person with stage 3 has a significantly increased risk of developing a life threatening illness.

However, by taking other medications alongside HIV treatment, a person with stage 3 can control, prevent, and treat serious complications.

Stage 3 HIV reduces the body’s ability to combat a range of infections, complications, and cancers.

Without treatment, latent infections that once caused minimal or no health problems may now pose a serious risk.

These are called opportunistic infections and may be a sign of stage 3 HIV.


Candidiasis is a fungal infection that typically occurs in the skin and nails, but it often causes serious problems in the esophagus and lower respiratory tract in people with stage 3 HIV.


Inhaling the fungus Coccidioides immitis may cause coccidioidomycosis. The infection is also referred to as valley fever.


This is an infection with Cryptococcus neoformansfungus. It may involve any part of the body, but the fungus usually enters the lungs and triggers pneumonia. It may also lead to swelling of the brain.

Cryptococcus gatti also causes cryptococcal infections.


Infection with the protozoan parasite Cryptosporidium can cause severe abdominal cramps and chronic, watery diarrhea for people with HIV.

Cryptosporidiosis is a common cause of diarrheal illness in people who do not have HIV. For people with a healthy immune system, symptoms typically last a couple of weeks. For people with severe or chronic diseases like stage 3 HIV, symptoms may last more than 2 months.

Cytomegalovirus disease (CMV)

CMV may cause a range of diseases, including:

  • pneumonia
  • gastroenteritis
  • encephalitis, a brain infection

CMV retinitis is a particular concern for people with stage 3 HIV. This is an infection of the retina at the back of the eye. Because it permanently impairs eyesight, it is a medical emergency.


An infection with the herpes simplex virus (HSV) causes herpes. It is typically transmitted through anal or vaginal intercourse without a barrier method. It can cause genital or oral ulcers.

HSV usually resolves within a few weeks if ulcers develop in a person with a healthy immune system. In people with stage 3 HIV, severe infections may develop.


This fungal infection causes severe, pneumonia-like symptoms in people with advanced HIV. Histoplasmosis can also become progressive and widespread, affecting organs outside the respiratory system.

Tuberculosis (TB)

TB develops from the bacterium Mycobacterium tuberculosis. It may transfer through the air if a person with an active infection sneezes, coughs, or speaks. Signs and symptoms include:

  • severe lung infection
  • cough
  • chest pain
  • weight loss
  • fever
  • fatigue

While TB is generally considered a lung infection, it can spread to the brain and other organs.

Infections with mycobacteria

Other types of mycobacteria, including Mycobacterium avium and Mycobacterium kansasii, are naturally present in soil and water. These mycobacteria do not generally cause infection in people who do not have underlying lung disease or compromised immune systems.

However, when a person has HIV, especially in the later stages, these infections can spread throughout the body and cause life threatening health issues.

Recurrent pneumonia

Many pathogens may cause pneumonia, but Streptococcus pneumoniae bacteria can be among the most severe for people with HIV. A vaccine for this bacterium is available. Doctors highly recommend everyone with HIV receive it.

Pneumocystis jirovecii pneumonia

An infection with this fungus can cause breathlessness, a dry cough, and a high fever in people with suppressed immune systems, including some people with HIV.


This occurs when the parasite Cystoisospora belli enters the body through contaminated food and water, causing:

  • diarrhea
  • fever
  • vomiting
  • weight loss
  • headaches
  • abdominal pain

Recurrent Salmonella septicemia

When Salmonella bacteria enter the body, they may cause typhoidal or nontyphoidal salmonella (NTS) infection.

NTS typically causes limited gastroenteritis disturbance in people with healthy immune systems.

However, in people with HIV, NTS may spread to the bloodstream, causing bacteremia or septicemia, which are bloodstream infections. They may be life threatening.


Toxoplasma gondii is a parasite that inhabits warm-blooded animals, such as cats and rodents, and is present in their feces. Humans may contract toxoplasmosis by:

  • drinking contaminated water
  • eating undercooked, contaminated food
  • ingesting the parasite accidentally, such as after changing cat litter or gardening

It can cause severe symptoms involving the:

  • lungs
  • retina
  • heart
  • liver
  • pancreas
  • brain
  • testes
  • colon

It is recommended to wear gloves while changing cat litter and thoroughly wash hands afterward to reduce the risk of contracting toxoplasmosis.

HIV-related encephalopathy

HIV can trigger encephalopathy, which is inflammation in the brain. Doctors do not fully understand the underlying mechanisms.

Progressive multifocal leukoencephalopathy (PML)

PML stems from infection with the John Cunningham (JC) virus. The JC virus is present in many people but usually lies dormant in the kidneys.

If a person has a weakened immune system, such as from HIV, the JC virus attacks the brain, leading to PML. It can be life threatening and cause paralysis and thinking difficulties.

Wasting syndrome

Wasting syndrome occurs when a person involuntarily loses 10% of their muscle mass through diarrhea, weakness, or a fever. Part of the weight loss may also involve fat loss.

Associated types of cancer

A person with HIV may have a higher risk of various types of cancer, including:

Learn more about HIV and cancer risk here.

Prevention is key to extending the life of a person with HIV.

It is important to manage a person’s viral load with HIV medications and take additional precautions, such as:

  • using barrier methods, such as condoms, to prevent other sexually transmitted infections (STIs)
  • receiving vaccinations for potential opportunistic infections
  • identifying and limiting exposure to any environmental factors that could lead to infection
  • avoiding foods with a high risk of contamination, such as undercooked eggs and meat, unpasteurized dairy and fruit juices, and raw seed sprouts
  • not drinking water straight from a lake or river, or unfiltered tap water in certain countries
  • asking a doctor about relevant vaccinations and ways to limit exposure to pathogens at work, at home, and on vacation

Antibiotic, antifungal, and antiparasitic drugs can help treat opportunistic infections.

If a person’s CD4 count drops below 200, a healthcare professional may want to start medications to prevent opportunistic infections.

Read more about the possible complications of HIV here.

Many misconceptions circulate about HIV that contribute to the harmful stigma of the virus.

The following activities or behaviors cannot transmit HIV:

  • shaking hands
  • hugging
  • kissing
  • sneezing
  • touching unbroken skin
  • sharing a toilet
  • sharing towels
  • sharing cutlery
  • mouth-to-mouth resuscitation
  • touching the saliva, tears, feces, or urine of a person with HIV

Read more myths and facts about HIV and AIDS here.

Doctors use three types of tests to detect and diagnose HIV.

There is a time period between exposure to HIV and when a test can detect it. This is known as the window period. The period can vary between people and the type of test used to detect it.

The three types of tests are:

  • Nucleic acid test (NAT): This blood test can determine how much virus is in a person’s blood. It can detect HIV the soonest after exposure, between 10 and 33 days.
  • Antigen/antibody tests: These test for antigens and antibodies by drawing blood from a vein or pricking a finger. They may detect HIV in a blood sample 18–90 days after exposure.
  • Rapid and self-tests: These test for antibodies in a person’s oral fluids or blood. They can detect HIV antibodies 23–90 days after exposure.

Healthcare professionals can test a person’s blood for HIV antibodies. Alternatively, people can use home testing kits.

Anyone who thinks they may be at risk of contracting HIV can have a rapid test. If the test results are negative, the test provider usually recommends having another test within a few weeks.

If a person thinks they have had exposure to HIV within the past 72 hours, they should talk with a healthcare professional about postexposure prophylaxis (PEP), a preventive treatment.

Learn more about the types of HIV tests available here.

There is currently no cure for HIV. However, treatments may help:

  • stop HIV from progressing
  • reduce the risk of transmissions
  • extend a person’s life expectancy
  • improve a person’s quality of life

Many people who take HIV treatments live long, healthy lives.

Treatments are lifelong, but medications are becoming increasingly effective and may require a person only taking one pill per day.

Emergency HIV pills: PEP

Anyone who may have had exposure to HIV within the past 72 hours should speak with a healthcare professional about getting PEP.

PEP may be able to stop the infection, especially if a person takes it as soon as possible after the potential exposure.

A person takes PEP for 28 days. A doctor monitors them for HIV afterward.

PEP is not 100% effective, so it is important to use preventive techniques, such as barrier protection and safe injection practices while taking PEP.

Antiretroviral drugs

Treating HIV involves taking antiretroviral medications that fight the infection and slow the spread of the virus.

People generally take a combination of medications, called highly active antiretroviral therapy or combination antiretroviral therapy. A person might refer to the approach as HAART or cART, respectively.

There are many types of antiretrovirals, including:

Protease inhibitors

Protease is an enzyme that HIV needs to replicate. Protease inhibitors bind to the enzyme and inhibit its action, preventing HIV from making copies of itself.

Types include:

  • atazanavir and cobicistat (Evotaz)
  • lopinavir and ritonavir (Kaletra)
  • darunavir and cobicistat (Prezcobix)

Integrase inhibitors

Integrase inhibitors block the enzyme integrase, which HIV needs to infect T cells. Due to their effectiveness and limited side effects, doctors often prescribe these as part of first-line treatment.

Integrase inhibitors include:

  • dolutegravir (Tivicay)
  • raltegravir (Isentress)

Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)

These drugs, also called “nukes,” interfere with HIV as it tries to replicate.

Types include:

  • abacavir (Ziagen)
  • lamivudine and zidovudine (Combivir)
  • emtricitabine (Emtriva)
  • tenofovir disoproxil fumarate (Viread)

Non-nucleoside reverse transcriptase inhibitors (NNRTIs)

NNRTIs also make it more difficult for HIV to replicate.

Types include:

  • doravirine (Pifeltro)
  • efavirenz (Sustiva)
  • etravirine (Intelence)
  • nevirapine (Viramune)

Chemokine coreceptor antagonists

These drugs prevent HIV from entering cells. However, doctors in the United States do not often prescribe them because they are not as effective as some other drugs.

Entry inhibitors

Entry inhibitors prevent HIV from entering T cells. HIV cannot replicate if it cannot enter these cells. Entry inhibitors are also uncommon in the United States.

People often benefit from a combination of antiretroviral drugs. The right combination depends on factors specific to each person.

Read more about HIV medications here.

Complementary or alternative medicine

Many people with HIV try complementary, alternative, or herbal remedies. However, there is no evidence these options are effective.

While mineral or vitamin supplements may benefit health in other ways, it is important to discuss them with a qualified healthcare professional before taking any. Some natural products can negatively interact with HIV treatments.

Learn more about alternative treatments for HIV here.

The following strategies can prevent contact with HIV.

Use barrier protection and PrEP

Using condoms or other barrier protection, such as dental dams, during anal, vaginal, and oral sex can drastically reduce a person’s chances of contracting HIV and other STIs.

While people who have undergone vaginoplasty or phalloplasty may be at risk of HIV with intercourse, more studies are needed.

In their 2023 guidelines, the U.S. Preventive Services Task Force advises that doctors only approve PrEP for people with recent negative HIV tests.

The task force also approves a PrEP formation, which is a combination of tenofovir disoproxil fumarate and emtricitabine. It advises people who take PrEP to do so once a day.

The Food and Drug Administration (FDA) has also approved a second combination drug, tenofovir alafenamide/emtricitabine, as PrEP.

Learn more about PrEP for transgender people here.

Use safe injection practices

Intravenous drug use is a key means of HIV transmission. Sharing needles and other drug equipment can expose a person to HIV and other viruses, such as hepatitis C.

Anyone who injects any drug should do so with a clean, unused needle.

Needle exchange programs can help reduce the prevalence of HIV.

Avoid exposure to relevant bodily fluids

To limit the risk of HIV exposure, a person can reduce contact with blood, semen, vaginal secretions, and other bodily fluids that can carry the virus.

Frequently and thoroughly washing the skin immediately after coming into contact with bodily fluids can also reduce the risk of infection.

To prevent transmission, healthcare workers use gloves, masks, protective eyewear, face shields, and gowns when exposure to these fluids is likely. They also follow established procedures to prevent transmission.

Learn more about contracting HIV here.


While certain antiretrovirals can harm the fetus during pregnancy, an effective, well-managed treatment plan can prevent transmission to the fetus.

Vaginal deliveries are possible if the birthing parent with HIV manages their condition well.

It may also be possible for the virus to transmit through breast milk. The Centers for Disease Control and Prevention (CDC) does not recommend breastfeeding or chestfeeding, regardless of a person’s viral load and whether they take antiretrovirals.

It is important to discuss all the options thoroughly with a healthcare professional.

Learn more about HIV and giving birth here.


Understanding the risk factors is crucial in avoiding exposure to HIV.

Learn more about HIV and AIDS in our dedicated hub here.

Many people with HIV live long, regular lives. However, due to the risk of damage to the immune system, it is important to adopt the following strategies.

Have a medication routine

Taking HIV medication as prescribed is essential. Missing even a few doses might jeopardize treatment.

A person should design a daily medication-taking routine that fits their treatment plan and schedule.

Sometimes, side effects keep people from sticking with their treatment plans. If any side effect is hard to manage, contact a healthcare professional. They can recommend a more easily tolerated drug and suggest other changes to the treatment plan.

Learn more about how HIV medications can affect the body here.

Boost overall health

Taking steps to avoid illness and other infections is key. People with HIV can exercise regularly, eat a balanced and nutritious diet, and avoid unhealthy activities, such as smoking, to boost their overall health.

It is especially important to prevent exposure to germs. This might require a person to stop eating unpasteurized foods and undercooked meats and avoid contact with animal feces and cat litter.

It is also crucial to wash hands well and regularly.

Learn about some ways to stop smoking here.

Stay in contact with doctors

HIV is a lifelong condition. Regularly checking in with a healthcare team can ensure that a person’s treatment aligns with their age and any other health issues. The care team can review and adjust the treatment plan accordingly.

Support mental health

HIV is highly stigmatized and shrouded in misconceptions. As a result, a person may feel persecuted, isolated, or excluded.

An HIV diagnosis can be very distressing. Feelings of anxiety or depression are common. Speaking with a mental health professional or a trusted doctor can help.

The CDC provides a list of services that can help people manage the stigma and discrimination and receive additional support.

Learn more about HIV and mental health here.

What is the main difference between HIV and AIDS?

HIV is a virus that attacks the body’s white blood cells. If it is left untreated, HIV may develop in three stages. AIDS refers to stage 3 HIV, which is the final and most severe stage.

How do you deal with HIV-positive status?

A person with an HIV-positive status should speak with a doctor to get treatment as soon as possible. Although there is no cure for HIV, early treatment can help stop the virus from progressing and spreading and improve a person’s quality of life.

How long can you live with HIV without knowing?

Approximately 13% of people with HIV do not know they have it. Some people may not have any symptoms during the first stage of HIV. However, two-thirds of people with HIV develop flu-like symptoms 2–4 weeks after contracting the virus.

Is having HIV serious?

Yes, HIV is serious, but treatment can help manage it.

HIV destroys the body’s white blood cells and reduces its ability to fight off other infections and diseases. If left untreated, HIV can lead to severe complications and develop into stage 3 HIV, which is life threatening.

HIV is a viral infection that reduces the effectiveness of the immune system. Due to advances in treatment, a person with access to quality healthcare and who takes antiretroviral medication can lead a long, regular life with HIV.

HIV transmits through some bodily fluids, such as semen, vaginal secretions, and blood. The most common means of transmission in the United States are sharing needles and having sex without using barrier protection or taking PrEP.

If someone with HIV does not receive treatment, possibly because they are unaware they have HIV, the disease can progress to stage 3 HIV, or AIDS. A person with stage 3 HIV is prone to a range of infections and other health issues that can be severe and life threatening.

Sometimes, HIV causes no symptoms for years or limited symptoms that can be easily mistaken for those of the flu. Anyone in the United States who suspects recent HIV exposure can find their nearest testing facility here.

Read the article in Spanish.