HIV is a virus that affects the immune system, increasing the risk and impact of other infections and diseases. Without treatment, HIV can progress to an advanced stage called stage 3 HIV, or AIDS.

Due to medical advances, people with HIV who have access to quality healthcare and receive appropriate treatment rarely develop AIDS, or stage 3 HIV.

The World Health Organization (WHO) and some other health agencies observe that many people with HIV manage the condition and live long healthy lives.

The life expectancy of a person with HIV is now approaching that of someone who tests negative for the virus. However, this only applies if the person takes a combination of drugs called antiretroviral therapy regularly and exactly how their doctor prescribes it.

As of 2020, around 73% of adults and 54% of children with HIV worldwide were receiving lifelong antiretroviral treatment.

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

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HIV stands for human immunodeficiency virus, and it attacks immune cells called CD4 cells. These are types of T cells — white blood cells that circulate around the body, detecting infections and faults and anomalies in other cells.

HIV targets and infiltrates CD4 cells, using them to create more copies of the virus. In doing so, it destroys the cells and reduces the body’s ability to combat other infections and diseases. This increases the risk and impact of opportunistic infections and some types of cancer.

However, it is worth noting that some people have HIV for long periods without experiencing any symptoms.

HIV is a lifelong condition, but treatments and certain strategies can prevent the virus from transmitting and the disease from progressing.

Learn about the stages of HIV here.

AIDS stands for acquired immunodeficiency syndrome. It is an advanced stage of HIV.

Doctors identify AIDS as having a CD4 count of fewer than 200 cells per cubic millimeter. They may also diagnose AIDS if a person has characteristic opportunistic infections, associated types of cancer, or both.

When a person with HIV does not receive treatment, the immune system gradually wears down, likely leading to stage 3 HIV. However, advances in antiretroviral treatments have made this progression increasingly less common.

In 2019, approximately 1.2 million people were living with HIV in the United States, and 15,815 people with HIV died. These deaths were due to any cause.

Learn more about HIV and AIDS here.

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

HIV can transmit when body fluids containing the virus come into contact with a permeable barrier in the body or small breaks in moist tissues of areas, such as the genitals.

Specifically, HIV can transmit via:

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

The virus cannot transmit through saliva, so a person cannot contract HIV through open-mouthed kissing, for example.

One of the main causes of HIV transmission in the U.S. is anal or vaginal intercourse. Transmission of HIV occurs when individuals do not use barrier protection, such as a condom, during intercourse or are not taking pre-exposure prophylaxis (PrEP), a treatment that aims to prevent HIV transmission among people with known risk factors.

Sharing equipment for injecting drugs is another main cause of HIV transmission in the U.S.

Less commonly, HIV transmits to babies during pregnancy, childbirth, or breastfeeding or chestfeeding.

There is also a chance of transmission through blood transfusions, though the risk is extremely low when blood donations undergo effective screening.

Learn more about the early detection of HIV here.

Undetectable = untransmittable

HIV can only transmit through fluids that contain a certain amount of the virus. If a person has undetectable levels of HIV, the virus cannot transmit to another person. While there’s effectively no risk of transmission during sex, risk reduction is still unknown for sharing injection drug equipment.

Additionally, the risk of transmission is very much reduced, but not negligible, for transmission during pregnancy and childbirth.

Some people use a shorthand to refer to the fact that undetectable levels of HIV are untransmittable: U=U.

Doctors consider HIV to be undetectable when the amount of the virus in the body is so low that a blood test cannot identify it.

Achieving undetectable levels requires a person to continually receive effective treatment and carefully follow the recommended treatment plan. This usually involves taking medications every day.

A person with undetectable levels still has HIV, and regular monitoring with blood tests is key to maintaining this status.

Learn more about HIV transmission here.

Progression to AIDS

The chances of HIV progressing to AIDS vary widely from person to person and depend on many factors, including:

  • 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.

For the most part, other infections — with bacteria, other viruses, fungi, or parasites — cause the more pronounced symptoms of HIV.

Early symptoms of HIV

Some people with HIV have no symptoms for months or even years after contracting the virus. Partly because of this, about 13% of people with HIV in the U.S. do not know that they have it.

While a person with no symptoms may be unlikely to seek care, there is still a high risk of transmission. For this reason, experts recommend regular testing so that everyone is aware of their HIV status.

Meanwhile, around two-thirds of people with HIV develop flu-like symptoms around 2–4 weeks after contracting the virus. These symptoms are collectively called acute retroviral syndrome.

Early symptoms of HIV may include:

These symptoms result from the immune system fighting off the infection. Anyone who has several of these symptoms and may have contracted HIV in the past 2–6 weeks should take a test.

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

Learn more about the early symptoms of HIV here.

Asymptomatic HIV

After the symptoms of acute retroviral syndrome resolve, many people may not experience any HIV symptoms for years.

While they feel well and appear healthy, the virus develops and damages the immune system and organs. If the person does not take medication that prevents the replication of the virus, this slow process can continue for 10 years or longer. However, some people may progress faster.

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

Learn more about antiretrovirals for HIV here.

Late-stage HIV infection

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.

When CD4 cells are severely depleted, at fewer than 200 cells per cubic millimeter, a doctor can diagnose stage 3 HIV.

Certain opportunistic infections involving bacteria, viruses, fungi, or mycobacteria also help a doctor identify stage 3 HIV.

Symptoms of Stage 3 HIV can include:

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

A person with HIV stage 3 has a significantly increased risk of developing a life threatening illness. Without treatment, people with AIDS typically live for around 3 years after diagnosis.

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

When a person with HIV takes effective treatment, the infection may never progress to stage 3. Treatment can also help a person recover some lost immune function, which will help ward off severe infections.

Learn more about the timeline for HIV here.

Stage 3 HIV reduces the body’s ability to combat a range of infections and associated complications and types of cancer.

Current treatment is often effective enough to keep many infections at bay. If a person with HIV does not receive treatment, latent infections that once caused minimal or no health problems can pose a serious risk. Doctors refer to these infections as opportunistic.

Below are some opportunistic infections that can signal to a doctor that a person has stage 3 HIV:

  • Candidiasis: 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 AIDS.
  • Coccidioidomycosis: Inhalation of the fungus Coccidioides immitis causes coccidioidomycosis. A doctor may refer to this infection in healthy people as valley fever.
  • Cryptococcosis: This is an infection with Cryptococcus neoformans fungus. 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.
  • Cryptosporidiosis: Infection with the protozoan parasite Cryptosporidium can lead to severe abdominal cramps and chronic, watery diarrhea.
  • Cytomegalovirus disease (CMV): CMV can cause a range of diseases, including pneumonia, gastroenteritis, and encephalitis, a brain infection. CMV retinitis is a particular concern for people with AIDS. This is an infection of the retina at the back of the eye, and it permanently impairs a person’s sight. It is a medical emergency.
  • Herpes: This results from infection with the herpes simplex virus (HSV). This virus usually transmits when people have anal or vaginal sex without using barrier contraception, such as a condom. It can also transmit through vaginal childbirth. A doctor may recommend that a person experiencing genital herpes close to delivery has cesarean delivery. This significantly lowers the risk of HSV transmitting to the baby.
  • Histoplasmosis: 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): The bacteria Mycobacterium causes TB. The bacteria can transfer through the air if a person with an active infection sneezes, coughs, or speaks. The signs and symptoms can include a severe lung infection, weight loss, a fever, and fatigue. It can spread to the brain and other organs.
  • Infections with mycobacteria: Types of mycobacteria, including Mycobacterium avium and Mycobacterium kansasii, are naturally present and tend to cause few problems. 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 different pathogens can cause pneumonia, but Streptococcus pneumoniae bacteria can be one of the most dangerous for people with HIV. A vaccine for this bacterium is available, and everyone with HIV should 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.
  • Chronic intestinal isosporiasis: This occurs when the parasite Isospora belli enters the body through contaminated food and water, causing diarrhea, fever, vomiting, weight loss, headaches, and abdominal pain.
  • Recurrent Salmonella septicemia: When Salmonella bacteria enter the body, usually via contaminated food or water, they can circulate and overpower the immune system, causing nausea, diarrhea, and vomiting. In this case, a doctor may diagnose recurrent Salmonella septicemia.
  • Toxoplasmosis: Toxoplasma gondii is a parasite that inhabits warm-blooded animals, including cats and rodents, and is present in their feces. Humans contract the resulting infection, called toxoplasmosis, by inhaling contaminated dust or eating contaminated food. It can cause severe symptoms involving the lungs, retina, heart, liver, pancreas, brain, testes, and colon. To reduce the risk of contracting toxoplasmosis, wear gloves while changing cat litter and thoroughly wash the hands afterward.

Related health problems

A person with advanced HIV or an opportunistic infection may experience complications, including:

  • HIV-related encephalopathy: HIV can trigger encephalopathy, or inflammation in the brain. Doctors do not fully understand the underlying mechanisms.
  • Progressive multifocal leukoencephalopathy (PML): PML stems from infection with the John Cunningham virus. This virus is present in many people, and it usually lies dormant in the kidneys. If a person has a weakened immune system, possibly due to HIV or medications, such as those for multiple sclerosis, the John Cunningham virus attacks the brain, leading to PML. It can be life threatening and cause paralysis and cognitive 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.

Learn about AIDS defining illnesses here.

Associated types of cancer

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

Kaposi sarcoma herpesvirus (KSHV), also known as human herpesvirus 8, causes a type of cancer that involves the growth of abnormal blood vessels. These can develop anywhere in the body.

It can be extremely dangerous if the cancer reaches organs such as the intestines or lymph nodes. A doctor may recognize characteristic solid, purplish, pink, brown, or black spots, which may be flat or raised.

In addition, Hodgkin and non-Hodgkin lymphoma have strong links to HIV. These cancers affect the lymph nodes and lymphoid tissues.

Also, a female with HIV should receive regular checks for cervical cancer. A recent study has found that women living with HIV have a higher risk for cervical cancer when compared with women without HIV infection. Receiving an early diagnosis can help limit the cancer’s spread.

Learn more about HIV and cancer risk here.

Preventing complications

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

It is important to manage the viral load with HIV medications and take additional precautions, such as:

  • using condoms to prevent other sexually transmitted infections (STIs)
  • having vaccinations for potential opportunistic infections
  • identifying and limiting exposure to any environmental factors that could lead to infection, including wearing gloves while changing cat litter
  • 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.

Read more about the possible complications of HIV here.

Many misconceptions circulate about HIV. These are harmful and stigmatizing.

The following activities or behaviors cannot transmit the virus:

  • shaking hands
  • hugging
  • kissing
  • sneezing
  • touching unbroken skin
  • sharing a toilet with someone who has HIV
  • 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.

Data suggest that about 13% of people with HIV in the U.S. are unaware of their HIV status.

Being aware of their HIV status is crucial for a person’s health and well-being, as it can enable them to access the necessary treatment early and prevent complications.

Healthcare professionals can test a person’s blood for HIV antibodies. They will retest the blood before confirming a positive result.

Home testing kits are also available.

Current HIV testing platforms make it possible to detect HIV in under 2 weeks. People with known risk factors should undergo testing more often.

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

The types of HIV tests are as follows:

  • Nucleic acid amplification tests, sometimes called NATs, can detect HIV as early as 10 days after exposure.
  • An antigen/antibody blood test can detect HIV in a blood sample as early as 18 days after exposure.
  • Most rapid tests and self-tests are antibody tests, and these can detect HIV antibodies as early as 21 days after exposure.

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

Additionally, there is a time between exposure to HIV and when a test can detect it known as the window period. However, the window period can vary between people and the type of test used to detect HIV.

Learn more about the types of HIV tests available here.

While there is no cure for HIV, treatments can stop it from progressing.

These treatments, called antiretrovirals, can reduce the risk of transmission. They can also extend a person’s life expectancy and improve their quality of life.

Many people who take HIV treatments live long, healthy lives. These medications are becoming increasingly effective, and most people tolerate them well. A person may need to take just one pill per day.

The following sections look at HIV treatments and medications for prevention.

Emergency HIV pills: PEP

Anyone who may have had exposure to the virus within the past 72 hours should speak with a healthcare professional about post-exposure prophylaxis (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, and a doctor monitors them for HIV afterward.

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

Antiretroviral drugs

Treating HIV involves taking antiretroviral medications, which 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 the first line of treatment.

Integrase inhibitors include:

  • dolutegravir (Tivicay)
  • raltegravir (Isentress)

Nucleoside and nucleotide reverse transcriptase inhibitors

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

Types include:

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

Non-nucleoside reverse transcriptase inhibitors

These drugs, called 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 U.S. 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 U.S.

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

HIV treatment is lifelong and involves taking pills on a regular schedule.

Each class of antiretrovirals has different side effects, but some common ones include:

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 that these are effective.

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

Learn more about alternative treatments for HIV here.

The following strategies can prevent contact with HIV.

Using barrier protection and PrEP

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

Transgender women and non-binary people assigned male at birth who have undergone vaginoplasty are at risk for HIV transmission when engaging in insertive vaginal sex with a partner who has a penis.

In their 2019 guidelines, the Preventive Services Task Force advises that doctors only approve PrEP for people with recent negative HIV tests.

They also approve a PrEP formation: a combination of tenofovir disoproxil fumarate and emtricitabine. They advise 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 and emtricitabine — as PrEP.

Learn more about PrEP for transgender people here.

Using 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 and addiction recovery programs can help reduce the prevalence of HIV.

Learn more about needle exchange programs and HIV here.

Avoiding exposure to relevant body fluids

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

Frequently and thoroughly washing the skin immediately after coming into contact with body 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, and they follow established procedures.

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 person with HIV controls the condition well.

It may also be possible for the virus to transmit through breast milk. The Centers for Disease Control and Prevention (CDC) do 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.

Having a medication routine

Taking HIV medication as prescribed is essential — missing even a few doses might jeopardize the 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.

Boosting overall health

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

It is especially important to prevent exposure to pathogens that cause infection. 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 the hands well and regularly.

Overall, antiretrovirals reduce the need for the above precautions.

Learn about some ways to stop smoking here.

Staying in contact with doctors

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

Supporting mental health

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

An HIV diagnosis can be very distressing, and 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.

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 U.S. are sharing needles and having sex without using barrier protection or taking PrEP.

If levels of HIV in the body are so low that a test cannot identify them, a person has an undetectable viral load. In this case, the virus cannot pass from them to someone else. Taking antiretrovirals can help a person achieve this.

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 AIDS is prone to a range of infections and other health issues that can be severe.

Sometimes, HIV causes no symptoms for years or limited symptoms that can be easy to mistake for those of the flu. Anyone in the U.S. who suspects recent HIV exposure can find their nearest testing facility here.

Read the article in Spanish.