HIV vs. AIDS

Medically Reviewed by Shruthi N, MD on September 03, 2024
Written by Marijke Vroomen Durning, RN
9 min read

HIV and AIDS are related, but they’re not the same.

HIV is a virus. It may cause AIDS after you’ve been infected for several years and it’s weakened your immune system.

Not everyone who has HIV will get AIDS. But the infection will advance to AIDS, usually in 10 to 15 years, if you don’t get treatment with antiretroviral drugs.

Many people with the virus don’t know they have it. Of the nearly 1.3 million people in the U.S. who have HIV, more than 160,000 haven’t been diagnosed and aren’t getting treatment.

There are about 36,000 new cases of HIV infection and about 17,000 AIDS diagnoses each year in the U.S.

Worldwide, there were 39.9 million people living with HIV as of 2023.

HIV stands for “human immunodeficiency virus.” It’s a virus that spreads from person to person. 

“Immunodeficiency” means your immune system, the system that fights illnesses in your body, isn’t working the way it should.

Your immune system includes white blood cells called T cells, also called T lymphocytes. These cells help keep you healthy by fighting infections. HIV attacks one type of T cell, the CD4 cell (also called helper T cells). The virus copies itself over and over, killing your CD4 cells. Without these cells, you’re more likely to get infections from bacteria, viruses, parasites, and fungi. Treatment called antiretroviral therapy (ART) lowers the amount of virus in the blood and stops the destruction of these cells.

When the virus was discovered, there were no treatments, so life expectancy for people with the virus was only a couple of years. But now with ART, people with HIV can live long and healthy lives as long as they continue to take their medications.

You can get HIV through direct contact with:

  • Blood
  • Semen
  • Vaginal fluid
  • Breast milk

The virus is usually passed from person to person through:

  • Sex
  • Sharing needles or other drug equipment
  • Mother-to-baby infection during pregnancy

Untreated HIV leads to a condition called AIDS, or acquired immunodeficiency syndrome.

AIDS is the third and most advanced stage of HIV infection, called stage III HIV. People who have AIDS either were never diagnosed with HIV, didn’t get treatment early enough to keep the infection from getting worse, didn’t take their ART drugs as prescribed, or stopped taking the treatment altogether.

The life expectancy of someone with AIDS can be as long as 3 years, but the prognosis can be only 1 year if they get an infection.

HIV and AIDS aren’t the same thing — HIV is a virus and AIDS is the condition caused by the virus. So, while they may have some symptoms in common, they’re quite different overall.

HIV symptoms

Not everyone with a new HIV infection, called primary infection or acute HIV, gets symptoms. If they do, they may be mild and not really noticeable. Others feel like they have the flu. Early signs and symptoms can appear about 2 to 4 weeks after you are infected. They include:

  • Fever
  • Headaches
  • Fatigue
  • Swollen lymph nodes in the neck and groin
  • Skin rash
  • Muscle aches
  • Joint pain
  • Sore throat
  • Painful mouth sores
  • Diarrhea
  • Weight loss (unintentional)
  • Cough
  • Night sweats

If you have these symptoms and might have been exposed to HIV, get tested right away.

AIDS symptoms

AIDS symptoms differ from HIV symptoms because they are related to the specific infection or illness you develop. Signs that you may have AIDS include:

  • Sudden weight loss
  • Night sweats
  • Fever that keeps coming back (recurrent)
  • Extreme fatigue, feeling very tired for no reason
  • Diarrhea that lasts more than a week
  • Sores in your mouth, in your anal area, or on your genitals
  • Pneumonia
  • Blotches on your skin or inside your mouth, nose, or eyelids
  • Memory problems
  • Depression
  • Persistent or frequent yeast infections (oral or vaginal)
  • Skin rashes or flaky skin that won’t heal
  • Pelvic inflammatory disease that doesn’t respond to treatment

People with AIDS get sicker with some types of infections than people who don’t have it. This is because their immune system can’t fend them off as well or at all. These opportunistic infections are what cause the signs and symptoms. The most common opportunistic infections that affect people with AIDS include:

When you have HIV, your doctor needs to keep an eye on how much of the virus is in your system. You might hear them call it your “viral load.” Typically, people with HIV should be tested every 3 or 4 months to see what their viral load is. Your doctor will tell you what schedule is right for you.

HIV tests check your blood or saliva for antibodies that your body makes in response to the virus. Earlier, you had to go to a doctor’s office, community health center, or a hospital to get an HIV test, but now many people with HIV take these tests at home with a self-test kit.

To do a self-test, you use a swab from the kit and rub it over your gums. After following the directions for your particular kit, you should have your result in about 20 minutes.

Two things will tell your doctor if your infection has become AIDS:

  • Your CD4 count. A person with a healthy immune system has 500 to 1,600 CD4 cells in a cubic millimeter of their blood. A person with AIDS has fewer than 200. This number is called your “CD4 count.”
  • AIDS-defining infections (opportunistic infections). These generally happen in people who have a CD4 count below 200. 

How long it takes HIV to become AIDS is different for everyone. If you don’t get treatment, it might take 10 to 15 years. With treatment, you may never have AIDS.

Treating HIV means taking antiretroviral therapy, or ART. The treatment doesn’t cure HIV, but the drugs help stop the virus from making copies of itself so it can’t attack your T cells. When your viral load is low, your immune system is healthier, which helps prevent infections and you have a lower chance of spreading the virus.

The goal is to lower the viral load to “undetectable” and keep it that way. If your blood tests show “undetectable viral load,” you can’t spread the virus through sexual activity. It’s important that you take your medicine every day as prescribed for this to happen. Everyone is different, but most people with HIV who take ART without missing doses can get their viral load under control within 6 months. If you have HIV, the earlier you start taking ART, the better the chances of successful treatment. 

HIV treatment begins with oral therapy, or pills. And there are many ART drugs approved to treat the virus. Most people who have HIV take at least three different drugs from two different classes (groups). Your doctor will prescribe a mix of these medications tailored to your specific needs. Many of the pills now already contain a mix of medications. This cuts down on the number of pills you need to take each day. Here are a few examples of combination drugs:

  • Atripla, which combines efavirenz, emtricitabine, and tenofovir disoproxil fumarate
  • Biktarvy, which is a mix of bictegravir sodium, emtricitabine, and tenofovir alafenamide fumarate
  • Cimduo, which combines lamivudine and tenofovir disoproxil fumarate
  • Combivir, which has lamivudine and zidovudine
  • Complera, which is a mix of emtricitabine, rilpivirine hydrochloride, and tenofovir disoproxil fumarate
  • Descovy, which combines mtricitabine and tenofovir alafenamide fumarate
  • Epzicom, which combines abacavir sulfate and lamivudine

There are also many single-drug pills, such as:

  • Edurant rilpivirine hydrochloride (also called RPV)
  • Intelence, etravirine (also called ETR)
  • Rescriptor, delavirdine mesylate (also called DLV)

Once your viral load is low enough or undetectable because of the pills, your doctor might recommend you switch to an injection (shot) treatment. These medications are longer-acting than pills and only have to be taken once a month or every 2 months.

Another form of treatment called pre-exposure prophylaxis (PrEP) helps reduce the risk of contracting HIV if you are at high risk of getting it. This is for people who don’t have HIV, not for those who have it already. If you're at risk of contracting HIV, speak to your doctor about starting PrEP treatment.

If you have HIV and it’s progressed to AIDS, your doctor will likely recommend you continue taking ART. It might help keep the viral load from getting much higher.

HIV is spread by contact with infected body fluids, so it can often be prevented. To protect yourself from getting HIV and prevent spreading it to others:

  • Always use a condom correctly when having sex.
  • Avoid injecting drugs. 
  • Take your ART medications exactly as prescribed.
  • Take PrEP medications if you're at high risk.
  • If you wish to become pregnant and you and/or your partner have HIV, speak with your doctor about how to reduce the risk of transmitting the virus to the baby.

AIDS is the most advanced stage of HIV. The best way to avoid AIDS is to start antiretroviral therapy as soon as possible. Taken every day as prescribed, these drugs will keep you healthy and make your viral level so low that it can’t be detected. Sticking to the right treatment can keep AIDS at bay for years and decades. It also greatly reduces the chances that you’ll pass HIV to your sexual partners and others. Many HIV-positive people live normal life spans.

HIV is a virus that can lead to AIDS, which some people call stage III HIV. HIV is often preventable but not curable. Instead, treatment — called ART — focuses on lowering the amount of the virus in your body so you don’t progress to AIDS. This will also keep the virus from spreading. It’s important to start ART as soon as possible and it’s vital that you take it exactly as prescribed for it to work properly.

Is there a vaccine for HIV?

Researchers are working on developing a vaccine for HIV, but it isn't available yet. That said, there is a treatment called PrEP that can reduce your risk of getting the virus if you're at high risk.

How long can someone with HIV live?

Many people with HIV live long, healthy lives, typically because they're taking antiretroviral therapy (ART) to keep the virus from multiplying in their body. 

What happens if you are HIV-positive?

If you are HIV-positive, it means the virus attacks your immune system, leaving it weak and not able to fight infections. The more the virus multiplies, the weaker your immune system becomes, and it progresses to AIDS.

Is HIV easy to catch?

HIV only spreads through infected body fluids, so it isn’t easy to catch, such as a cold or the flu. You have to be in contact with the fluid and it has to get inside your body. This could happen through sex or using a contaminated needle if you use drugs, for example.

Who is at the highest risk for HIV?

Anyone can get HIV, but people who have the highest risk are those who are gay or bisexual and men who have sex with other men.

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