HIV and AIDS

Human immunodeficiency virus (HIV) is the virus that causes HIV infection. Without treatment, HIV can progress to acquired immunodeficiency syndrome (AIDS), the most advanced stage of HIV infection.

Overview

Over the past four decades, there has been tremendous progress in advancing the science of human immunodeficiency virus (HIV) testing, prevention, and treatment. Today, there are safe and effective ways to prevent HIV acquisition, as well as treatment that allows people with HIV to live long, healthy lives without transmitting HIV to others.

HIV attacks and destroys CD4 cells in the immune system. These cells help the body fight viruses. The loss of CD4 cells makes it difficult for the body to eliminate viruses, illnesses, and certain cancers.

Without treatment, HIV can gradually destroy the immune system and may progress to immunodeficiency syndrome (AIDS), the most advanced stage of HIV illness. With treatment, the body can prevent HIV from destroying CD4 cells, allowing the immune system to recover and protect against other infections.

Effective treatment is available. Antiretroviral therapy (ART) allows people with HIV to live long, healthy lives. NIH-funded research showed that, when taken as prescribed, ART can reduce the amount of HIV in the blood to a level so low that it cannot be transmitted to sexual partners. This concept is known as Undetectable = Untransmittable, or U=U.

Signs and Symptoms

When it comes to HIV, knowing the signs and symptoms can help. But here’s the thing: Not everyone with HIV has symptoms. In fact, some people don’t feel sick at all until the infection has progressed to AIDS. That’s why it’s so important to learn the basics and know when to get tested.

Early (Acute) Symptoms

Some people develop flu-like symptoms two to four weeks after getting HIV. These early signs, called acute HIV symptoms, are your body’s natural response to the virus. Common symptoms may include:

  • Fever
  • Chills
  • Rash
  • Night sweats
  • Muscle aches
  • Sore throat
  • Fatigue
  • Swollen lymph nodes
  • Mouth ulcers or sores

These symptoms can look a lot like other common illnesses, so it’s easy to miss or dismiss them. Don’t assume you have HIV just because you have any of these symptoms, they can be similar to those caused by other illnesses. If you think you may have been exposed to HIV, then get an HIV test. The most important takeaway: The only way to know for sure if you have HIV is to get tested regularly.

Starting HIV treatment during acute HIV has the best prognosis

Later Symptoms: Chronic or Advanced HIV

After the acute phase of a new infection, HIV moves into what’s often called chronic HIV, clinical latency, or asymptomatic HIV. During this stage, the virus is still active, but it multiplies very slowly. Many people don’t have any symptoms at all—and this phase can last for years for some people.

Just because you feel fine doesn’t mean HIV isn’t affecting you. The inflammation from the infection causes damage to your body. Without treatment, this stage can last 10 to 15 years (sometimes less) but will eventually progress.

Taking your medicine as prescribed can keep the virus undetectable. If you maintain an undetectable viral load, then you can live a long, healthy life—and you won’t transmit HIV to your sexual partners.

However, it’s important to remember that if your viral load becomes detectable, then you can pass the virus to others—even if you have no symptoms. That’s why regular checkups and routine lab work are so important.

AIDS: The Most Advanced Stage of HIV Infection

If HIV isn’t treated, it can progress to stage 3, also known as AIDS (acquired immunodeficiency syndrome). At this point, the immune system is severely weakened and can't fight off certain infections and illnesses, and some cancers become more likely. Many of the serious illnesses seen in people with AIDS come from opportunistic infections. These are conditions that take advantage of the body’s weakened immune system.

Symptoms of AIDS can include:

  • Rapid weight loss
  • Recurring fever or heavy night sweats
  • Extreme and unexplained tiredness
  • Swollen lymph nodes that last for weeks
  • Diarrhea that lasts more than a week
  • Sores in the mouth, anus, or genitals
  • Pneumonia
  • Memory loss, confusion, or other neurological issues

These symptoms might be linked to other health problems—but if you’re experiencing them, it’s time to talk to your healthcare provider and get tested or re-engage in HIV treatment. If you have been diagnosed with HIV, then a health professional will use specific criteria to determine whether HIV has progressed to AIDS. Most people can reverse the complications of AIDS once they are on medicine to suppress the virus and medications that treat the infections caused by the damaged immune system.

Related Health Effects

Without treatment, HIV can gradually damage the immune system and increase the likelihood of getting other infections, like fungal infections, lung infections, tuberculosis, and some sexually transmitted infections (STIs).

People living with HIV/AIDS can become very sick from common conditions that often are more severe in people with weakened immune systems. These conditions include:

  • Viral infections that cause skin tumors, liver disease, and pneumonia
  • Fungal infections of the mouth, lungs, and genitals
  • Bacterial infections spread through the air like tuberculosis
  • Certain cancers

People with HIV may develop aging-related conditions at younger ages, even when the virus is well controlled on antiretroviral therapy. People with HIV are more likely than people without HIV to develop cardiovascular disease. Older people with HIV are more likely to have:

Mental health conditions are common in the United States. Anyone can experience poor mental health or a mental illness. People with HIV may be more likely to experience some mental health conditions. For example, people with HIV are more likely to experience depression as people without HIV. It is important to remember that mental health conditions are treatable and that people can recover from poor mental health.

People with HIV are at special risk for oral health problems. Some of the most common oral health problems are:

Oral health conditions can be painful, annoying, and can lead to other health problems. ART has made some oral health problems less common. The most common oral health problems linked with HIV can be treated. Talk with your doctor or dentist about what treatment might work for you.

Causes and Risk Factors

When the viral load is high enough to be detectable by a viral load test, HIV can spread through specific body fluids (blood, semen, vaginal fluids, rectal fluids, and breast milk) most commonly through sex without a condom, shared needles, or perinatal transmission (from parent to child during pregnancy, birth, or infant feeding).

How HIV can Be Spread

Through blood:

  • Sharing needles or syringes for injecting drugs or tattooing
  • Being exposed to the blood of a person with HIV through accidental needle sticks
  • Sharing personal items that may have blood on them, such as razors or toothbrushes

Through semen, pre-seminal fluid, vaginal fluids, and rectal fluids:

  • Having vaginal or anal sex
  • Having oral sex (less likely, but possible in rare cases)

Remember U=U: A person living with HIV who is on treatment and maintains an undetectable viral load has zero risk of transmitting HIV to their sexual partners.

Through perinatal transmission:

Babies can be exposed to HIV while breastfeeding or through blood during pregnancy and childbirth, especially if the mother is not taking ART during or after pregnancy.

How HIV Does Not Spread

HIV cannot be transmitted through:

  • Casual contact: Hugging, closed-mouth kissing, or shaking hands
  • Environmental surfaces or items: Door handles, shared food, drinks, or utensils, swimming pools, or toilet seats
  • Through the air
  • Body fluids: Mucus (including when coughing or sneezing), saliva, sweat, tears, or urine
  • Insects or animals: Ticks, mosquitoes, other insects; dogs, cats, or other household animals

Factors That Increase Transmission Risk

When someone with HIV does not receive treatment or their treatment is not working, some circumstances can increase the chances they will spread HIV to others:

  • Having sex without a condom
  • Having untreated STIs, such as genital herpes
  • Having a detectable viral load
  • Using drugs that affect judgment or decision-making
  • Sharing needles or drug injection equipment

Prevention Guidance

  • Get tested for HIV. Talk to your partners about HIV testing and get tested before you have sex. Use the GetTested locator from the CDC to find an HIV testing location near you.
  • Get tested and treated for STIs. Ask your partners to get tested and treated, too. Having an STI can increase your risk of getting HIV or transmitting it to others.
  • Use condoms correctly every time you have sex. HIV is mainly transmitted through anal or vaginal sex without a condom.
  • Talk to your healthcare provider about pre-exposure prophylaxis (PrEP). PrEP is an HIV prevention option if you do not have HIV and want to lower your chances of getting HIV. PrEP involves taking HIV medicine on a routine schedule to prevent HIV transmission in the event of possible HIV exposure.
  • Consider post-exposure prophylaxis (PEP). PEP is taken within 72 hours after possible exposure to HIV to prevent HIV. PEP should be used only after possible exposure and is not meant for regular use.
  • Do not share needles. If you inject drugs, use only sterile drug injection equipment and water, and never share your equipment with others.

Diagnosis

HIV Testing

It is possible to have HIV and not know it. The only way to know for sure whether you have HIV is to get tested.

A small blood sample, mouth swab, or urine sample is used to test people for HIV. It can take as long as three to six months after initial exposure for signs of the virus to show up in the blood, and years before symptoms appear.

You can be tested at:

  • A doctor’s office
  • A hospital
  • A community health center or other health clinic
  • Mobile testing vans
  • AIDS services organizations
  • At home, using an FDA-approved at-home testing kit

Use the CDC GetTested locator to find an HIV testing location near you.

Everyone aged 13 to 64 should be tested at least once for HIV. If you are older than 64 and are at risk for HIV, talk with your doctor about how often you should be tested. People should get tested more often when they have had more than one sex partner or are having sex with someone whose sexual history they don't know.

If you choose to take a test at home, make sure to use a test that is approved by the U.S. Food and Drug Administration (FDA). Follow up with your doctor to confirm the results of at-home tests. If necessary, your doctor can help you start treatment.

After Testing

Starting treatment as soon as possible after a positive test leads to better results. A person’s first visit with a healthcare provider after testing positive for HIV includes a review of the person’s health and medical history, a physical exam, and several lab tests.

The following lab tests help doctors decide the best treatment:

  • CD4 count measures the number of CD4 cells in a blood sample.
  • Viral load measures how much virus is in the blood. When taken as prescribed, HIV treatment keeps viral load so low that that the virus cannot be detected by a viral load test. When HIV is not detected, it cannot be transmitted.
  • Drug-resistance testing identifies which HIV medicines will not be effective against a person’s strain of HIV, so the right medicines can be prescribed.

AIDS Diagnosis

People with HIV are diagnosed with AIDS if their CD4 count is less than 200 cells/mm3. They could also be diagnosed if they have AIDS-defining conditions, or certain opportunistic infections or cancers like Kaposi's sarcoma.

Viral load should be measured every every three to four months. People with HIV should talk with their health care team to determine how often they should have viral load testing

Treatment and Management

Antiretroviral Therapy (ART)

The treatment for HIV is called ART. ART involves taking a combination of HIV medicines on a regular schedule, usually every day for pills or once a month, every six months, or less often for injections. ART is recommended for everyone who has HIV.

ART cannot cure HIV, but it helps people with HIV live long, healthy lives. ART also reduces the risk of HIV transmission including mother-to-child transmission.

After an HIV diagnosis, it is important for people to start taking HIV medicines as soon as possible. Research shows that people who start HIV treatment early can live longer than people who delay treatment.

How ART Works

HIV medicines prevent HIV from multiplying or making copies of itself. This reduces the amount of HIV in the body. Having less HIV in the body gives the immune system a chance to recover and produce more CD4 cells that help the body fight infection.

In most people who take HIV medicine as prescribed, the viral load will drop to an undetectable level. A person has an undetectable HIV viral load if their viral load remains undetectable for at least six months after their first undetectable test result.

Even when viral load is undetectable, HIV is still present in the body. The virus stays in a small number of cells in the body. These are called viral reservoirs. If treatment is stopped, the virus begins to multiple, becoming detectable in the blood again.

People on ART generally take a combination of two or three HIV medicines. In many cases, multiple HIV medicines may be combined into a single pill or capsule that is taken once a day. There are also newer long-acting medicines given by injection every two weeks to six months that may be appropriate for some people with HIV.

Side Effects and Drug Interactions

Sometimes HIV medicines can cause side effects. Most side effects from HIV medicines are manageable, but a few can be serious. Overall, the benefits of HIV medicines far outweigh the risk of side effects.

HIV medicines also can interact with other medicines. Healthcare providers carefully consider potential drug interactions before recommending an HIV treatment regimen. If you believe you are experiencing side effects from HIV medicines, talk to your healthcare provider before stopping or adjusting your treatment regimen.

Treatment for Related Conditions

People with HIV may receive treatment for complications and conditions associated with well-controlled HIV. These include medicines to treat and prevent illnesses that are common in people with HIV, such as viral hepatitis and tuberculosis, cardiovascular disease, certain cancers, neurological disorders, and oral health conditions.

Living With HIV

A positive HIV test often leaves a person overwhelmed with questions and concerns. It is important to remember that HIV can be treated effectively with HIV medicines.

After testing positive for HIV, it is important to see a healthcare provider as soon as possible, even if you do not feel sick. Prompt medical care and treatment with HIV medicines is the best way to stay healthy.

Issues such as lack of health insurance or an inability to pay for certain HIV medicines can make it hard to take HIV medicines consistently. Healthcare providers can recommend resources to help people access treatment.

People with HIV can involve their partners in their treatment plans. Research shows that support from loving relationships and from the community can help individuals take medicine as prescribed.

The following are some questions that people with newly diagnosed HIV typically ask their healthcare providers:

  • What can I do to stay healthy and avoid getting other infections?
  • How can I prevent passing HIV to others?
  • How will HIV treatment affect my lifestyle?
  • How should I tell my partner that I have HIV?
  • Is there any reason to tell my employer and those I work with that I have HIV?
  • Are there support groups for people with HIV?
  • Are there resources available to help me pay for my HIV medicines?

Tips for People Living With HIV

  • Take ART as prescribed. When taken as prescribed, HIV medicines can eliminate the possibility that you will transmit HIV to your partner through sex.
  • Maintain an undetectable viral load. People with HIV who maintain an undetectable viral load have no risk of transmitting HIV to their sexual partners. This concept is known as Undetectable = Untransmittable, or U=U.
  • Disclose your HIV status to your sexual partners.
  • Remain engaged with your healthcare team.

Preventing Mother-to-Child Transmission

HIV medicines taken during pregnancy, childbirth (including vaginal delivery), and breastfeeding can reduce the likelihood of perinatal HIV transmission. Evidence suggests that the odds of perinatal transmission are less than 1% when breastfeeding with an undetectable viral load. Feeding infants using properly prepared formula or pasteurized human donor milk from a milk bank can eliminate the chances of perinatal HIV transmission completely.

HIV and Older Adults

Nearly half of people with HIV in the United States are aged 50 and older. Many have lived with HIV for decades. Others acquired HIV more recently. Older people are less likely than younger people to get tested, so they may not know they have HIV. Signs of HIV can be mistaken for the aches and pains of normal aging. Doctors do not always think of testing older people for HIV.

Even when the disease is well controlled, people with HIV may develop aging-related conditions, such as cardiovascular disease or osteoporosis at younger ages. Talk with your doctor about how living with HIV could affect you as you grow older.

Here are some key areas for people aging with HIV to focus on:

  • Heart health and metabolism: People with HIV may be at higher risk for heart disease and type 2 diabetes, requiring regular blood pressure, cholesterol, and glucose checks.
  • Bone and kidney health: Long-term HIV infection and HIV medications can affect both bone density and kidney function, so ask your provider about bone scans and monitoring your renal function.
  • Managing multiple medications and potential interactions: People aging with HIV may see an increase in medications they take. Managing drug interactions and simplifying treatment regimens with pharmacies and care teams are key to staying in control.
  • Cognitive well-being: Aging with HIV can bring unique cognitive changes, so check in with a health care provider regularly and be alert for changes that might cause concern. Don't delay evaluating new symptoms.
  • Lifestyle and prevention: Staying physically active, eating well, avoiding tobacco, and keeping up with screenings matter now more than ever.

Find Treatment

The following resources can help you find HIV care and services:

  • Available Care and Services is a webpage from the Ryan White HIV/AIDS Program outlining the services available for people with HIV who are low-income and have inadequate health insurance or no health insurance.
  • Living With HIV is a webpage from CDC with information on living with an HIV diagnosis, including recommendations on how to share an HIV diagnosis with others.
  • CDC HIV/AIDS site has information on HIV/AIDS risk factors, screening, prevention, and treatment.

Find Clinical Trials

Clinical trials uncover better ways to prevent, diagnose, treat, and understand diseases and conditions. To ensure results apply to everyone, volunteers of all ages, sexes, and backgrounds, including both healthy individuals and those with specific medical conditions, are needed. Find studies on HIV.

Community Support

The following organizations provide information and support for people with HIV:

Note: This resource list is for informational purposes only. It is not comprehensive, and an organization’s inclusion does not constitute an endorsement by NIH.  

Research Information

The National Institutes of Health (NIH) is the largest public funder of biomedical research in the world. NIH invests most of its budget in medical research seeking to enhance life and to reduce illness and disability. NIH-funded research has led to breakthroughs and new treatments helping people live longer, healthier lives, and building the research foundation that drives discovery.

NIH provides the largest public investment in HIV research globally. As HIV crosses nearly every area of medicine and scientific investigation, the response to the HIV pandemic requires a multi-institute, multidisciplinary, global research program.

NIH supports a comprehensive HIV research portfolio to increase adoption of existing evidence-based prevention and treatment, meet the needs of people aging with HIV, address co-occurring conditions associated with HIV, develop novel formulations to support choice and widespread access in HIV prevention and treatment, and continue to pursue a cure for HIV.

Find NIH-funded research projects using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies.