HIV/AIDS: Symptoms, Causes, and How It Is Diagnosed and Treated
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is HIV/AIDS, and how is it treated?
HIV is a virus that attacks CD4 T cells, weakening the immune system, and untreated it can progress to AIDS within 7 to 10 years. Testing is the only way to know your status. Daily antiretroviral therapy lowers the virus to undetectable levels, at which point people with HIV are highly unlikely to transmit it through sex. [1] [2]
What the research says
Twice-yearly lenacapavir prevented almost all infections in a large trial. In PURPOSE 2, a randomized trial of 3,265 cisgender men, transgender women and men, and gender-nonbinary people, HIV infections occurred in 2 participants on lenacapavir (0.10 per 100 person-years) and 9 on daily oral emtricitabine-tenofovir (0.93 per 100 person-years), against a background incidence of 2.37 per 100 person-years. Injection-site reactions led 26 of 2,183 participants (1.2%) on lenacapavir to stop, compared with 3 of 1,088 (0.3%) on the daily pill (Kelley et al., New England Journal of Medicine, 2024 [3]).
Long-acting PrEP has also been studied in pregnancy and breastfeeding. In a PURPOSE 1 substudy, 487 of 5,345 enrolled women had one or more pregnancies. Lenacapavir exposure did not differ significantly by trimester or after birth compared with non-pregnant participants. The drug was present in breastmilk (median breastmilk-to-plasma ratio 0.52), but exposure in breastfed infants was minimal (infant-to-maternal plasma ratio 0.02) (Bekker et al., The Lancet HIV, 2026 [4]).
Prevention tools are not reaching everyone equally. A meta-analysis of 114 articles (514,543 participants) found that PrEP awareness was 61.4% among gay men but 42.9% among bisexual men, and use of U=U was 76.3% versus 69.3%, with odds ratios between 1.52 and 2.77 across these measures (Zhou et al., Journal of the International AIDS Society, 2026 [5]).
What HIV and AIDS Are
HIV stands for human immunodeficiency virus. It is an infection that damages specific cells of the immune system, making the body less able to clear out infections and diseases. If HIV infection is not treated, over time it can cause an illness called acquired immunodeficiency syndrome (AIDS) [1].
It helps to understand the two terms as stages of the same condition. HIV is the virus and the infection it causes. AIDS is the most advanced stage of that infection, reached when the immune system has been damaged enough that the body can no longer fight off infections it would normally control.
HIV spreads through contact with some body fluids. The virus can spread during sex, when people share needles or syringes, or during pregnancy, delivery, or breastfeeding. The only way to know if you have HIV is to get tested [1].
The encouraging news is that HIV is treatable and preventable. Medicine can control HIV levels in the blood. This keeps the infection from getting worse, so some people never get AIDS [1].
Symptoms of HIV, Stage by Stage
The symptoms of HIV and AIDS vary depending on the person and the stage of infection. The infection moves through recognizable stages [1].
Stage 1 — Primary (acute) infection. When a person gets HIV, the first stage can feel like the flu. This happens around 2 to 4 weeks after the virus enters the body. Common symptoms include fever, swollen lymph glands (mainly on the neck), sore throat, rash, muscle aches, diarrhea, and weight loss. Other early symptoms can include headache, joint pain, dry cough, night sweats, and mouth sores.
These symptoms can last for days or weeks. Symptoms may be serious, but some people have mild or no symptoms during this stage. Even with mild or no symptoms, HIV spreads easily to others during the acute stage.
Stage 2 — Clinical latent (chronic) infection. After the acute stage, symptoms often go away. HIV stays in the body, and the infection enters this quieter stage, which can last for many years. Over time, the infection weakens the body's ability to clear out germs.
Symptomatic HIV infection. As the immune system weakens, people may develop other infections such as shingles, thrush (a yeast infection in the mouth), and pneumonia. Persistent symptoms that don't go away can include fever, fatigue, swollen lymph glands, diarrhea, and weight loss.
Progression to AIDS. Without treatment, an HIV infection continues to damage the immune system. After 7 to 10 years, the infection can progress to AIDS. People with AIDS are more likely to have infections that would be easily controlled by a working immune system, and some cancers are also more common. AIDS symptoms include recurring fever, swollen lymph glands, ongoing diarrhea, and rapid weight loss, along with sweats, chills, white spots or lesions on the tongue or mouth that don't go away, fatigue, and skin rashes or bumps.
Thanks to treatment for HIV, many people do not develop AIDS.
Stage | Timing | Typical Symptoms |
Primary (acute) infection | About 2–4 weeks after exposure | Fever, swollen lymph glands, sore throat, rash, muscle aches, diarrhea, weight loss; also headache, joint pain, dry cough, night sweats, mouth sores |
Clinical latent (chronic) infection | Years, often symptom-free | Symptoms often go away; virus quietly weakens the immune system |
Symptomatic HIV infection | As immunity declines | Shingles, thrush, pneumonia; persistent fever, fatigue, swollen glands, diarrhea, weight loss |
AIDS | Typically 7–10 years without treatment | Recurring fever, ongoing diarrhea, rapid weight loss, sweats, chills, lasting mouth sores, skin rashes |
When to See a Doctor
If you might have come into contact with HIV, see a healthcare professional right away. There is medicine that can help stop the virus. This medicine, called post-exposure prophylaxis (PEP), works best if you start taking it within three days after contact with the virus [1].
The timing matters because every hour counts after a potential exposure. Acting quickly opens the door to medication that can dramatically lower the chance of infection taking hold.
Causes: How HIV Damages the Immune System
HIV is caused by a virus that attacks white blood cells called CD4 T cells. This weakens the immune system and allows germs to cause infection and disease. The immune system can't clear HIV from the body. That means HIV must be treated with medicine to prevent damage [1].
People with untreated HIV can spread it through sexual contact, sharing needles or syringes, contact with blood, and during pregnancy, delivery, or breastfeeding from birth parent to child.
Over time, even without symptoms, untreated HIV infection causes CD4 T cell levels to drop. In someone with a typical immune system, there are between 500 and 1,600 CD4 T cells in a blood sample. When the CD4 number falls below 200 cells, HIV infection has progressed to AIDS.
Measure | Typical Range | AIDS Threshold |
CD4 T cell count (cells in blood sample) | 500–1,600 | Below 200 |
Risk Factors
You are more likely to get HIV if you are sexually active, have contact with infected blood, share needles or syringes, or have been diagnosed with a sexually transmitted infection [1].
HIV can spread through sexual activity, including oral sex. Your risk of getting HIV is higher if your partner has HIV or is at high risk of HIV, and the risk goes up if you don't regularly use a condom or other barrier during sexual activity.
Your HIV risk is higher if you have been diagnosed with a sexually transmitted infection, especially syphilis. People who have anal sex also have a higher risk. For males, the risk is higher if you are not circumcised. Other factors that raise risk include bleeding during sex or having sex during a menstrual period. Children born to a parent with untreated HIV have a higher risk of HIV during pregnancy, birth, or breastfeeding.
Your risk also goes up if you share needles or syringes. Getting a tattoo may raise your risk of HIV exposure. People in certain jobs with regular exposure to blood may be at higher risk. HIV can also be transmitted through blood products or transfusion if blood isn't screened — though the risk this way is very low in the United States because donated blood is screened and tested for HIV.
HIV risk factors do not include casual contact. You cannot get HIV or AIDS by hugging, kissing, dancing, or shaking hands with someone who has the infection. Sharing dishes does not spread HIV. Toilet seats do not spread HIV. HIV is not spread through the air, water, or insect bites. You cannot get HIV by donating blood. You can't get HIV from someone's sweat, tears, or saliva.
Increases HIV Risk | Does NOT Spread HIV |
Sex without a barrier, especially with a partner who has HIV or is at high risk | Hugging, kissing, dancing, shaking hands |
Anal sex | Sharing dishes or toilet seats |
STI diagnosis, especially syphilis | Air, water, or insect bites |
Sharing needles or syringes; tattoos | Donating blood |
Contact with infected blood; certain jobs with blood exposure | Sweat, tears, or saliva |
Pregnancy, delivery, or breastfeeding with untreated HIV | Casual everyday contact of any kind |
Complications of Untreated HIV
HIV infection weakens your immune system, making you much more likely to get many infections and certain types of cancers [1].
Infections linked with HIV and AIDS include pneumonia (both bacterial pneumonia and Pneumocystis pneumonia, or PCP); candidiasis (thrush), a fungal infection that causes a thick, white coating on the mouth, tongue, esophagus, or vagina; tuberculosis (TB), a bacterial infection mainly affecting the lungs; cytomegalovirus (CMV), which stays in the body for life and can damage the eyes, digestive system, lungs, or other organs when immunity weakens; cryptococcal meningitis, a fungal infection of the membranes and fluid around the brain and spinal cord; and toxoplasmosis, a parasitic infection that can cause severe lung or brain disease.
Cancers linked to HIV and AIDS include lymphoma, which affects the system of immune organs, glands, vessels, and lymph nodes; Kaposi sarcoma, a tumor of the blood vessel walls that may appear pink, red, purple, brown, or black depending on skin color and can affect internal organs; and cancers related to human papillomavirus (HPV), including cancers of the vulva, vagina, cervix, anus, penis, and throat.
Other complications include wasting syndrome (severe weight loss often with diarrhea and fever), brain and nervous system complications ranging from confusion, forgetfulness, and difficulty walking to severe dementia, kidney disease (HIV-associated nephropathy, or HIVAN), and liver disease, mainly in people who also have hepatitis B or hepatitis C.
Complication Type | Examples |
Infections | Pneumonia (including PCP), candidiasis/thrush, tuberculosis, cytomegalovirus, cryptococcal meningitis, toxoplasmosis |
Cancers | Lymphoma, Kaposi sarcoma, HPV-related cancers (cervix, anus, throat, and others) |
Other | Wasting syndrome, brain and nervous system damage, kidney disease (HIVAN), liver disease |
How HIV Is Diagnosed
HIV can be found in the body with blood tests or tests on fluid from the mouth. Blood may be collected from a vein or from a finger stick. Testing can be done in a clinic or healthcare professional's office, and you may also be able to order an at-home test for HIV [2].
Screening at least once for HIV is recommended for all people age 13 to 65. Getting tested more often may be recommended if you have risk factors.
Different tests detect HIV at different points after exposure, which is why timing matters.
Test Type | What It Detects | Detects Infection After Exposure |
Viral load (HIV RNA) test | Genetic material from the virus | About 10–33 days |
Antigen/antibody combination test | Viral antigen plus the immune response | About 18–90 days |
Antibody-only test | The immune system's antibodies | About 23–120 days |
If a test is done too early, it may not catch an infection, so a negative result may need to be repeated. If there is detectable genetic material from HIV in the blood but the antibody or antigen tests are negative, this result suggests an early HIV infection. The test may be repeated to rule out a false positive result.
If your results are positive and you live in the United States, a state health department staff member may contact you.
People diagnosed with HIV may work with a specialist. HIV specialists help you decide on baseline tests and follow-up testing, guide your treatment including selecting antiretroviral therapy (ART), and help you manage your health overall.
Ongoing testing typically includes CD4 T cell counts, which help determine the stage of infection (AIDS is diagnosed if counts fall below 200 cells); viral load measurements (also called HIV RNA), where the goal of treatment is to lower the viral load to an undetectable level; and medicine resistance testing, since some HIV strains are no longer affected by certain medicines and identifying the strain helps pick the best treatment.
You may also get tests and screening for other infections or complications, including tuberculosis, hepatitis B or C, sexually transmitted infections, liver or kidney damage, cervical and anal cancer, cytomegalovirus, and toxoplasmosis.
Treatment: Antiretroviral Therapy (ART)
Once you have an HIV infection, your body can't get rid of it. Medicines are used to control HIV and to prevent complications. This medicine is called antiretroviral therapy (ART). It is a mix of two or more medicines that work together to lower the amount of HIV in the blood. This also helps prevent HIV from becoming resistant to the medicine [2].
Treatment should lower your viral load so that it can't be found in the blood. Regular blood tests check viral load and CD4 T cell counts. Even if HIV cannot be found in the blood, that doesn't mean your HIV is gone — HIV is still in your body, but ART prevents it from making viral particles.
There are many ART options that mix more than one type of HIV medicine into a single pill taken once a day. The main classes of HIV medicine are:
ART Class | How It Works |
Integrase inhibitors | Stop an enzyme called integrase, keeping HIV from putting viral genetic material into a cell |
NRTIs (nucleoside or nucleotide reverse transcriptase inhibitors) | Stop HIV from copying its RNA into DNA, so HIV can't make viral copies easily |
Protease inhibitors | Block an enzyme called protease, damaging HIV's ability to make new virus particles |
ART is a part of treatment for everyone with HIV, no matter your CD4 T cell count or symptoms. For the best results, take ART medicines as prescribed. Don't miss or skip doses.
Talk with your healthcare professional about possible side effects or trouble you may have taking medicines. Treatment side effects depend on the class of ART medicine you take. Possible side effects of some ART medicines can include nausea, vomiting, or diarrhea; heart disease; kidney and liver damage; and weakened bones or bone loss. ART medicines can also make cholesterol levels harder to manage. Mental health conditions or substance use issues can make it hard to stay on ART, and there are ways these issues can be managed with professional help.
Regular follow-ups let your healthcare team check your response to treatment. Viral load is checked 4 to 6 weeks after starting ART, and after that, every three months for at least the first two years of treatment.
Some health issues that are part of aging may be harder to manage if you have HIV. Some medicines that are common for age-related heart, bone, or metabolic conditions may not mix well with anti-HIV medicines. If another health professional prescribes medicine for another condition, be sure to mention your HIV therapy so they can check for issues with taking the medicines together.
Prevention: PEP, PrEP, and U=U
To prevent HIV, take actions that lower your risk: get tested and treated for any sexually transmitted infections, since these make it easier to get or spread HIV; ask sexual partners if they have HIV and tell your partners if you have HIV; use condoms correctly, every time; do not share needles or syringes and use new, sterile equipment each time; and if you are pregnant, get medical care that includes an HIV test right away [1].
Some people may consider circumcision. People who have a foreskin seem to get HIV through sexual contact at a higher rate than people who've been circumcised.
Also consider pre-exposure prophylaxis (PrEP). These medicines help prevent HIV infection when taken as directed among people at high risk. Some PrEP medicines are pills; others are given as a shot.
PrEP Option | Form and Schedule | Notes |
Tenofovir disoproxil fumarate + emtricitabine (Truvada) | Tablet, once a day | Daily oral pill |
Tenofovir alafenamide fumarate + emtricitabine (Descovy) | Tablet, once a day | Approved for males and transgender women; not approved for people who have receptive vaginal sex |
Cabotegravir (Apretude) | Injection every two months | Long-acting injectable option |
Lenacapavir (Yeztugo) | First dose as tablet + injection, then injection every six months | The longest dosing interval among the options |
Before you start PrEP, your healthcare professional will do an HIV test, repeated every three months. You need to take PrEP pills every day or closely follow the shot schedule. PrEP protects only against HIV, so use safe sex practices and get tested for sexually transmitted infections as recommended.
If you have HIV, taking antiretroviral therapy (ART) as directed can lower the amount of virus in your blood to where it is not detectable by tests. At this level, people are highly unlikely to spread HIV through sex. This is referred to as Undetectable = Untransmittable (U=U).
If you think you've been exposed to HIV, wash the area with soap and water. If there is eye exposure, rinse with water or use an eye wash station for 15 minutes. Then contact your healthcare professional or workplace health resource, or go to an emergency room. After contact or possible contact with HIV, medicines to block HIV are started within the first 72 hours. This is called post-exposure prophylaxis (PEP). These medicines are very effective in lowering your risk of getting HIV. You need to take the medicine for 28 days.
Lifestyle and Home Support
Taking antiretroviral therapy medicine on schedule and working with your healthcare team are vital for HIV management. There are also things you can do every day to support your health [2].
Get all recommended vaccinations. Common vaccines prevent illnesses such as pneumonia, influenza, COVID-19, and mpox. Other vaccines that may be recommended include HPV, hepatitis A, and hepatitis B. Some vaccines that use weakened but infectious viruses may only be safe if your CD4 T cell counts are high enough; other types of vaccines may be offered regardless of your CD4 count.
Avoid foods that carry a high risk of foodborne illness. People with HIV can become seriously ill from foodborne illness. Thoroughly cook food to a safe temperature. Avoid eating raw eggs, meat, or seafood. Wash all raw vegetables and fruit thoroughly. Don't leave food out for too long. Avoid dairy and juices that haven't been pasteurized, and don't drink water that isn't treated to remove germs.
Focus on hand hygiene if you have a pet. Caring for a pet can raise your risk of some infections. Wash hands thoroughly after handling pets or emptying litter boxes.
Supplements and HIV Medicines
Nothing replaces the benefit of antiretroviral therapy for HIV treatment. Also important is avoiding risky behavior or habits that aren't healthy, such as smoking [2].
If you're interested in dietary supplements, talk with your healthcare professional before taking any supplements to make sure they won't affect the way your medicines work. Supplements that are known to interfere with HIV medicines include St. John's wort and garlic.
Coping and Living With HIV
People living with HIV can find it overwhelming. Negative reactions are common, and these feelings may go away over time. HIV infection can be treated, and people with HIV often live long and healthy lives [2].
But if you or someone you're caring for is considering suicide, get help now. You can call a local emergency number or a suicide hotline. In the U.S., call or text 988 to reach the 988 Suicide & Crisis Lifeline, available 24 hours a day, every day, or use the Lifeline Chat. Services are free and confidential. If you're a U.S. veteran or service member in crisis, call 988 and then press 1, or text 838255.
If it's safe to do so, talk about your diagnosis with people who can support you. Ask for help if you need it, and talk with them about how you're feeling. Seeing a therapist can help you manage the feelings this diagnosis can cause. Joining a support group for people with HIV may also help you connect with others going through the same diagnosis.
Preparing for Your Appointment
If you think you might have an HIV infection, you're likely to start by seeing your family healthcare professional. You may see an infectious disease specialist who focuses on treating HIV/AIDS [2].
Before your appointment, think about the answers to these questions: How do you think you were exposed to HIV? What are your symptoms? Do you have risk factors, such as having sex without protection or injecting illicit drugs? What medicines or supplements do you take?
Your healthcare professional will ask questions about your health and lifestyle and do a physical exam, checking for swollen lymph nodes, sores on your skin or in your mouth, issues with your nervous system, unusual sounds in your lungs, and swollen organs in your belly.
In the meantime, protect yourself and others before your appointment. Don't have sex without using protection. If you inject illicit drugs, always use a fresh, clean needle, and never share needles with others.
The Bottom Line
HIV is no longer the diagnosis it was decades ago. It is a manageable, treatable condition — and one that is highly preventable. The only way to know your status is testing, and every person age 13 to 65 should be screened at least once, more often if risk factors are present.
If exposure may have just happened, PEP started within 72 hours can dramatically cut your risk. If you're at higher risk, PrEP offers reliable ongoing protection. And if you're living with HIV, taking ART as prescribed can lower the virus to undetectable levels, protecting your own health and making transmission through sex highly unlikely.
Take action this week: If you've never been tested, schedule an HIV screening — at-home tests and local clinics make it straightforward and confidential. If you think you were exposed in the last 72 hours, seek care immediately to ask about PEP. Don't wait for symptoms; early testing and treatment change everything.
Frequently Asked Questions
What is the difference between HIV and AIDS?
HIV is the virus that attacks the immune system's CD4 T cells. AIDS is the most advanced stage of untreated HIV infection, diagnosed when CD4 T cell counts fall below 200 cells in a blood sample. With treatment, many people with HIV never develop AIDS.
What are the first symptoms of HIV?
The first stage, called acute HIV, happens around 2 to 4 weeks after exposure and can feel like the flu: fever, swollen lymph glands on the neck, sore throat, rash, muscle aches, diarrhea, and weight loss. Headache, joint pain, dry cough, night sweats, and mouth sores can also occur.
How long can HIV stay silent before causing AIDS?
The clinical latent stage can last for many years with no symptoms. Without treatment, HIV infection typically progresses to AIDS after 7 to 10 years, as it slowly damages the immune system.
How is HIV transmitted?
HIV spreads through contact with certain body fluids: during sex, when people share needles or syringes, through contact with blood, and during pregnancy, delivery, or breastfeeding. It is not spread by hugging, kissing, sharing dishes, toilet seats, the air, water, or insect bites.
How soon can an HIV test detect infection?
A viral load (HIV RNA) test can detect infection about 10 to 33 days after exposure. An antigen/antibody combination test detects it around 18 to 90 days after exposure. An antibody-only test detects it around 23 to 120 days after exposure, so testing too early may need to be repeated.
Can HIV be cured?
Once you have HIV, your body can't get rid of it. However, antiretroviral therapy (ART) controls the virus, lowers it to undetectable levels, prevents progression to AIDS, and lets many people live long, healthy lives.
What is U=U (Undetectable = Untransmittable)?
Taking ART as directed can lower the virus in the blood so it can't be detected by tests. At that level, people with HIV are highly unlikely to spread HIV through sex.
What is PrEP, and how does it prevent HIV?
Pre-exposure prophylaxis (PrEP) is medicine taken by people at high risk to prevent HIV infection. It comes as daily pills or periodic injections (every two or six months, depending on the option). Before starting, an HIV test is done and repeated every three months.
What should I do if I think I was exposed to HIV?
Wash the area with soap and water (rinse eyes for 15 minutes if exposure was in the eyes), then contact a healthcare professional or go to an emergency room. Post-exposure prophylaxis (PEP) — medicines started within 72 hours and taken for 28 days — is very effective at lowering your risk.
What side effects can HIV medicines cause?
Possible side effects depend on the ART class and can include nausea, vomiting, or diarrhea, heart disease, kidney and liver damage, weakened bones or bone loss, and harder-to-manage cholesterol. Never skip doses without talking to your healthcare professional.
Related Reading
Protease Inhibitors: Types, How They Work and Side Effects explains protease inhibitor medicines.
Antiretroviral Therapy (ART) for HIV: How It Works and Side Effects explains antiretroviral therapy for HIV.
Antivirals: What They Treat, How They Work and Side Effects explains antiviral medicines and how they work.
Post-Exposure Prophylaxis (PEP): How It Works and When to Start explains emergency HIV prevention after a possible exposure.
Learn more in our guide to HIV Test: Types, Window Periods, How It Works and Results.
Learn more in our guide to STD Testing (STI Testing): Who Needs It, Test Types and What Results Mean.
Learn more in our guide to HIV Viral Load: Test, Normal Range, Results and What They Mean.
Flow Cytometry: What It Is, Why It's Done, How It Works and Results explains the lab test that sorts and counts cells by their surface markers to help diagnose and monitor blood cancers and immune conditions.
CD4 Count: Normal Range, What a Low CD4 Count Means and How Often It's Checked explains the blood test that tracks helper T cells and immune strength.
References
Mayo Clinic Staff. HIV/AIDS - Symptoms and causes. Mayo Clinic. May 22, 2026. https://www.mayoclinic.org/diseases-conditions/hiv-aids/symptoms-causes/syc-20373524
Mayo Clinic Staff. HIV/AIDS - Diagnosis and treatment. Mayo Clinic. May 22, 2026. https://www.mayoclinic.org/diseases-conditions/hiv-aids/diagnosis-treatment/drc-20373531
Kelley CF, Acevedo-Quiñones M, Agwu AL, et al. Twice-yearly lenacapavir for HIV prevention in men and gender-diverse persons. New England Journal of Medicine. 2024;392(13):1261-1276. PMID 39602624. https://doi.org/10.1056/NEJMoa2411858
Bekker LG, Moodley D, Diallo DD, et al. HIV acquisitions, safety, and pharmacokinetics of lenacapavir for HIV pre-exposure prophylaxis in pregnant and lactating women (PURPOSE 1): a substudy of a phase 3, randomised controlled trial. The Lancet HIV. 2026;13(9):e621-e630. PMID 42442378. https://doi.org/10.1016/S2352-3018(26)00112-8
Zhou Q, Sun X, Chaires S, et al. Disparities in awareness, willingness and uptake of biomedical HIV prevention among bisexual and gay men: a systematic review and meta-analysis. Journal of the International AIDS Society. 2026;29(6):e70132. PMID 42231594. https://doi.org/10.1002/jia2.70132
Further Reading and Credible Sources
This article is for general informational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional about any medical condition.
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