Human immunodeficiency virus, or HIV, is a virus that attacks the body’s immune system — specifically, white blood cells called CD4-positive (CD4+) T-helper cells.

Those cells, which are sometimes referred to as CD4 cells, T-helper cells, or T4 cells, play an important role in identifying pathogens that invade the body and in marshaling an immune response against them. Left untreated, HIV infiltrates and destroys CD4 cells over three stages, impairing the immune system’s ability to fight off infections and diseases.

When the number of CD4 cells drops low enough, or certain infections related to an impaired immune system occur, a person may be diagnosed with the final stage of HIV infection: acquired immunodeficiency syndrome, or AIDS.

When the immune system is weakened from AIDS, the body may have difficulty fighting off certain cancers or viral, fungal, or bacterial infections, and these conditions may prove fatal.

While there’s no cure for HIV yet, effective HIV treatment, known as antiretroviral therapy (ART), can reduce the amount of virus to undetectable levels, allow people to live longer, healthier lives, and help prevent the virus’s transmission to others.

Read on to learn about HIV symptoms, the different stages of the virus, HIV risk factors, advances in treatment options and their effectiveness, and much more.

Common Questions & Answers

What is the difference between AIDS and HIV?

HIV is an abbreviation that stands for human immunodeficiency virus. If you are HIV positive it means that an HIV test has detected the presence of the virus in your body. HIV attacks your body’s immune system.

AIDS is an acronym that stands for the disease caused by HIV, acquired immunodeficiency syndrome. It is a late stage of HIV infection in which the virus has actively damaged the immune system.

What are the first signs of HIV and AIDS?

Rapid weight loss, drenching night sweats, extreme fatigue, swollen lymph glands, diarrhea, and pneumonia are common early signs of both HIV and AIDS.

Can HIV kill you?

HIV leads to AIDS, which can kill you. Most people don’t die of AIDS per se but of the many opportunistic infections that can occur as a result of the damage the disease does to the immune system.

What are the stages of HIV infection?

There are three stages of HIV infection: (1) acute HIV infection, which happens right after the virus has been transmitted and may cause a viral-like illness; (2) latency, a period of time during which the virus is inactive and a person may be unaware of the infection; and (3) AIDS, during which the virus actively damages the immune system.

Is it possible to be infected with HIV and not know it?

Yes. About 1 in 7 people currently infected with HIV do not know they are infected, according to the Centers for Disease Control and Prevention (CDC). Without treatment, most people infected with the virus will develop AIDS within 2 to 15 years.

Signs and Symptoms of HIV/AIDS

There are three main stages of HIV infection, each with its own symptoms.

Stage 1: Acute HIV Infection

Within the first two to four weeks after HIV infection, about two-thirds of people will experience symptoms that feel like a really bad flu. As the immune system rallies to fight off the virus, fever may develop along with additional symptoms, such as sore throat, swollen glands, mouth sores, rashes, diarrhea, fatigue, headache, and muscle and joint pain.

This stage, called acute infection or primary HIV infection, can last for a few days, or it can stretch into weeks.

Stage 2: Clinical Latency

If the infection goes undiagnosed or untreated, the immune system can bring the HIV level down some, but it can’t completely control or contain it; the virus is still active but multiplies more slowly, often without causing any symptoms. This is also called the clinical latency stage, or chronic HIV infection, and the timeline of these HIV symptoms can last up to 15 years.

At this stage, people with HIV who aren’t taking medication still have a sufficient amount of virus in their system to transmit it to others, even if they don’t have symptoms, and the virus continues to damage the immune system over that time, leading to worsening health.

Stage 3: AIDS

If a person goes for years without treatment for HIV, the third stage is AIDS. Even after a diagnosis of AIDS, though, recovery is possible with ART, and people can go on to live full, healthy lives with antiretroviral medications.

AIDS symptoms can include:

Sudden weight loss
Recurring fever
Night sweats
Fatigue and weakness
Swollen lymph glands
Chronic diarrhea
Sores in the mouth, anus, or genitals
Blotches on the skin, under the skin, or inside the mouth, nose, or eyelids
Neurological issues, including memory loss and depression

Some of these symptoms may be the result of a so-called opportunistic infection, such as pneumonia, which an immune system badly damaged by HIV can’t effectively fight.

Learn More About Signs and Symptoms of HIV

Causes and Risk Factors of HIV/AIDS

HIV is spread by direct contact with certain body fluids from a person with HIV who has a detectable viral load. These fluids are:

Blood
Semen (cum) and preseminal fluid
Rectal fluids
Vaginal fluids
Breast milk

For transmission to occur, the virus in these fluids must enter the bloodstream of an HIV-negative person through a mucous membrane (found in the rectum, vagina, mouth, or tip of the penis), through open cuts or sores, or direct injection.

In the United States, HIV is mostly spread through sex, particularly anal and vaginal intercourse. People can also transmit HIV by sharing used injection equipment, such as syringes and other paraphernalia.

Mothers can spread HIV to babies during pregnancy, birth, and breastfeeding.

HIV is a flimsy virus that can’t live for long outside the human body and can’t reproduce without a human host. That means it isn’t spread through saliva on silverware; from kisses on the cheek, hugs, sharing toilets, or closed-mouth kissing; or by mosquitoes, ticks, and other insects.

If a person is on effective antiretroviral treatment for HIV, they can lower their viral load to an undetectable level, at which point they effectively have no risk of sexually transmitting HIV to their HIV-negative partners.

Learn More About HIV Transmission

How Is HIV/AIDS Diagnosed?

Who Should Be Tested for HIV

The CDC recommends that everyone ages 13 to 64 get tested for HIV at least once.

People with a higher risk of HIV should get tested more frequently. The CDC defines people in this higher-risk HIV group as those who have:

Had more than one sex partner in the past year
Had an HIV-positive partner
Been diagnosed with or treated for hepatitis, tuberculosis, or a sexually transmitted disease in the past year
Exchanged sex for drugs or money
Shared injection equipment

If you aren’t in any of these higher-risk groups but you think your partner may be, the CDC thinks you should be tested, too.

People who are pregnant or trying to become pregnant should also be tested. If you do have HIV, starting treatment in pregnancy can dramatically reduce the chance that your child will be born with HIV.

For men who have sex with men, the CDC recommends annual HIV testing, but it also notes that some doctors may advise a schedule of every three to six months for certain patients, depending on other risk factors.

Types of HIV Tests

There are lots of options for HIV tests. There are tests that analyze saliva, blood, or even urine. Tests screen for different signs of HIV infection: antibodies (proteins your body makes to fight the virus); antigens (proteins on the surface of HIV cells that trigger the production of antibodies); or actual genetic material from the HIV virus.

Which test you take depends on how recently you think you may have been exposed to HIV, how long you want to wait for results, and how you feel about blood draws.

Nucleic Acid Test (NAT): 10 to 33 Days After an Exposure For people with flu-like symptoms and a recent high-risk exposure, a NAT (also known as a viral load test) can detect HIV’s genetic material in the blood. This test must be taken in a clinic and is expensive. Usually, healthcare providers use it to confirm other tests.

Antibody/Antigen Test: 18 to 45 Days After an Exposure This test, commonly performed in a lab, checks for both antibodies and antigens. Antigens are detectable in the blood before antibodies develop, signaling the presence of HIV. An antibody/antigen test can be a rapid test that uses blood from a finger prick and delivers results in less than 30 minutes. Or it could be a test that uses blood drawn from a vein and delivers results in a few days.

Antibody Test: 23 to 90 Days After an Exposure An antibody-only test uses a fluid sample swabbed from inside your cheek or blood from a finger prick. These rapid tests and at-home tests can detect HIV antibodies three weeks after exposure (at the earliest) and deliver results in 20 to 30 minutes. They are also good at detecting chronic HIV.

There are antibody-only tests that use blood drawn from a vein rather than a finger prick. These tests can typically detect the infection sooner after exposure but take several days to deliver results and are conducted at a lab.

All positive antibody tests should be followed up with an additional test to confirm results.

Learn More About HIV Testing and Diagnosis

Diagnosis of AIDS

A person is diagnosed with AIDS when one of two things happens:

CD4 cell count drops from normal levels of 500–1,200 cells per cubic millimeter to 200 cells or fewer.
As the CD4 count drops, usually the volume of HIV in the blood, known as the viral load, rises.
Viral, fungal, or bacterial infections, and cancers, which healthy immune systems can fight off, emerge and worsen. These so-called AIDS-defining conditions are often the cause of death for people living with HIV who are not receiving treatment.

Prognosis of HIV

A positive diagnosis of HIV can be overwhelming, but effective treatment exists, and it’s important to start treatment as soon as possible. With the right medicines, people with HIV can now live longer, healthier lives with a very low risk of transmission to others.

Treatment and Medication Options for HIV

If you test positive for HIV, research shows that if you start taking medicine immediately (or even return to treatment after some time off) and stay on it, you can bring the amount of virus in your blood (your viral load) to undetectable levels, protect your immune system, and prevent transmission to others.

Agencies like the National Institutes of Health (NIH) recommend you start HIV treatment as soon as possible after diagnosis.

Talk to a healthcare provider about treatment choices and the resources that are available to you.

There are no-fee or low-cost programs that ensure that everyone, no matter their income or insurance status, can receive and stay on treatment.

Medication Options

There are more than 30 different HIV drugs, divided into eight classes. Known collectively as antiretroviral therapy (ART), they prevent the virus from replicating in different ways.

People typically take a combination of three drugs from at least two different classes, although new drug combinations require only two medicines, combined in one pill.

Most antiretroviral drugs need to be taken every day to work properly. Although it can be difficult to stick to this routine, it’s a must in order to keep your viral load (the amount of HIV in your body) low and avoid developing possible drug resistance.

In January 2021, the U.S. Food and Drug Administration (FDA) approved the first long-acting treatment for HIV. The once-a-month injection, administered by a healthcare provider, is a combination of cabotegravir and rilpivirine — sold under the brand name Cabenuva — and is meant for patients who have already lowered their viral load.

The shots could be especially beneficial for people who struggle with a daily pill schedule.

Side Effects of Medication

All medicines have potential side effects, and HIV medicines are no different. When you first start ART, you may experience:

Anemia
Diarrhea
Headache
Fatigue
Nausea
Nerve problems
Rash
Pain

When taken long term, certain HIV medicines can be associated with serious side effects, such as high cholesterol, lipodystrophy (gain or loss of body fat), diabetes, osteoporosis, or liver damage. However, the newer HIV medications have a much lower risk of these side effects and are safer to take. Ask your doctor what to expect and how to stay healthy.

According to the NIH’s Office of AIDS Research, ART is recommended for all transgender people with HIV, though some antiretroviral drugs may interact with gender-affirming hormone therapy. Be sure your doctor is aware of any other medications and supplements you’re taking and is monitoring you for any interactions.

Learn More About Treatment for HIV

Prevention of HIV

There are a number of strategies that can reduce your risk of becoming infected with HIV or greatly lower the odds that you will transmit the virus to an HIV-negative partner.

If you are using ART regularly and precisely as prescribed and have lowered your viral load to consistently undetectable levels (which usually takes up to six months, followed by ongoing care

), your risk of transmitting the virus to a sexual partner is essentially zero. Research shows this method of HIV prevention is 100 percent effective in preventing sexual transmission.

You can also reduce your risk of getting or transmitting HIV if you and your partner:

Use HIV prevention medications, an approach called pre-exposure prophylaxis (PrEP)
Take a combination of HIV medicines within 72 hours after you think you may have been exposed, an approach called post-exposure prophylaxis (PEP)
Use condoms correctly and consistently
Have a circumcised penis
Never share drug injection equipment
Limit your number of sexual partners
Abstain from sex or choose less-risky sexual behaviors, such as oral sex or mutual masturbation instead of anal or vaginal sex
Get checked and treated for other sexually transmitted diseases

HIV can be passed from mother to child at any point during pregnancy, but if you’re pregnant and have HIV, you can prevent this by making sure you take your HIV medicines as directed so that you have an undetectable viral load. By adhering to treatment throughout pregnancy, labor, and delivery, and if your baby takes HIV medicine two to six weeks after birth, you can lower the risk of transmission to 1 percent or less.

To understand your options for lowering your HIV risks, consider checking out the CDC’s Risk Reduction Tool.

PrEP (Pre-Exposure Prophylaxis)

The FDA has approved two oral medications to prevent HIV transmission: Truvada and Descovy. Both pills combine the medicine emtricitabine with a version of the drug tenofovir. When taken every day as directed, these medications have been found to be 99 percent effective in preventing sexual transmission of HIV and between 74 and 84 percent effective in preventing transmission of HIV through the shared use of injection equipment. Some people find it difficult to stick to a daily medication regimen, though.

In December 2021, the FDA approved the injectable drug cabotegravir (Apretude), a shot given once every two months. In clinical trials, Apretude was shown to be more likely to reduce the risk of HIV by 69 percent for cisgender men and transgender women who have sex with men, compared with the daily PrEP drug Truvada in pill form. For cisgender women at high risk of HIV, the injection reduced the risk of contracting the virus by 90 percent over treatment with daily oral Truvada.

PrEP is recommended for people at high risk of becoming infected with HIV. This includes people who have a sexual partner with HIV (especially someone with an unknown or detectable viral load), people dating someone in the first six months of HIV treatment (before they reach undetectable status), sexually active transgender people, people attempting to conceive with a partner who is living with HIV, and people who have had a sexually transmitted infection in the past year.

For transgender women, preliminary data suggests that PrEP medicines do not reduce the effectiveness of gender-affirming hormones.

But estrogen has been found to slightly reduce the levels of PrEP drugs. It’s not yet known whether that decreases PrEP’s effectiveness. Research is ongoing.

PEP (Post-Exposure Prophylaxis)

If you think you may have been exposed to HIV — for instance if a condom broke or you have experienced a sexual assault — you can also take medicine after the event to prevent yourself from acquiring HIV. If you visit a healthcare provider and begin taking the medicine within 72 hours of exposure, it can prevent any HIV in your system from setting up shop and proliferating. Emergency rooms are a common provider of PEP.

Once you start the medicine, you will take it for 28 days, until the medicine runs out. PEP is highly effective (though not 100 percent); the sooner it’s started, the better.

For people who frequently require PEP, doctors may suggest treatment with PrEP instead.

Complications of HIV

People with HIV that is left untreated are at increased risks for heart disease and neurological problems.

And that’s before HIV progresses to AIDS. Without treatment, the immune system’s CD4 cells become so damaged and destroyed that the body becomes susceptible to dangerous and fatal infections and certain cancers — specifically, lymphomas (cancers of the lymph nodes), Kaposi sarcoma (a blood vessel cancer), and invasive cervical cancer.

According to the CDC, if a person’s CD4 count falls below a certain level or a person develops one of these infections or cancers, they will be diagnosed with AIDS, the last stage of HIV. This usually happens after years of untreated HIV infection. You can reduce the chance you’ll be diagnosed with AIDS by getting tested early and taking antiretroviral therapy consistently and exactly as directed to reduce the amount of virus in your bloodstream.

People diagnosed with AIDS who are not on treatment are at high risk of becoming infected by a wide range of viruses and microbes, including bacteria, fungi, and parasites — these are called opportunistic infections (OIs) and include pneumonia and tuberculosis.

Usually, antiretroviral therapy restores the immune system and prevents OIs in people living with HIV. Still, some people aren’t diagnosed with HIV until they also qualify for an AIDS diagnosis. Or they may not be taking ART consistently, or their treatment isn’t keeping their viral load low enough for their immune system to do what it needs to.

Learn More About Complications of HIV

Research and Statistics: How Many People Have HIV/AIDS?

In 2021, about 36,000 people were diagnosed with HIV in the United States, according to the latest figures available from the CDC. The annual number decreased by approximately 7 percent between 2017 and 2021.

The CDC further estimates that roughly 1.2 million people in the United States were living with HIV at the end of 2021, and that about 13 percent of those individuals were unaware they were HIV-positive.

Male-to-male sexual contact accounted for about 67 percent of new HIV diagnoses; heterosexual sexual contact accounted for 22 percent; injection drug use accounted for 7 percent; and male-to-male sexual contact in combination with injection drug use accounted for 4 percent.

Globally, the HIV pandemic continues, with an estimated 39 million people living with HIV in 2022, according to UNAIDS.

Anyone can acquire HIV, but the prevalence of HIV is not the same in all communities and varies depending on social and demographic factors.

Despite the existence of effective treatment, people still die of AIDS-defining illnesses, though it’s difficult to know how many. The CDC now identifies the number of people with HIV who died in a year, but it doesn’t separate out deaths from AIDS-defining illnesses. In 2020, 18,489 people living with HIV in the United States and dependent territories died of any cause.

HIV and Black and Latino Americans

While HIV can affect anyone, regardless of race or ethnicity, it impacts certain U.S. communities disproportionally. As the CDC notes, this is due to a number of social and economic factors — including stigma, discrimination, income, education, and geographic region — that can affect HIV risk.

According to the latest data from the CDC, Black Americans account for both a higher proportion of new HIV diagnoses and people with HIV, compared with other races and ethnicities. Specifically, in 2021, Black Americans made up 12 percent of the U.S. population but 40 percent of new HIV diagnoses.

An estimated 46 percent of new diagnoses in the transgender population were Black transgender women.

While women accounted for only about 19 percent of new HIV diagnoses in 2019, 54 percent of those diagnoses were among Black women.

Hispanic/Latino Americans accounted for 18 percent of the U.S. population in 2021 but 25 percent of people with HIV.

Editorial Sources and Fact-Checking

Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.

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