What is HIV?
HIV stands for human immunodeficiency virus. All viruses must infect living cells to reproduce. HIV takes over certain immune system cells that are supposed to defend the body. These are called CD4 cells, or T cells.
When HIV takes over a CD4 cell, it turns the cell into a virus factory. It forces the cell to produce thousands of copies of the virus. These copies then infect other CD4 cells. Infected cells don't work well, and they die early. Over time, the loss of CD4 cells weakens the immune system, making it harder for the body to stay healthy.
What is AIDS?
AIDS stands for acquired immunodeficiency syndrome. Most people with HIV do not have AIDS. And most people with HIV will not develop AIDS if they start treatment soon after becoming infected and continue to take their treatment consistently. A person is said to have AIDS when their immune system becomes so weak it can't fight off certain kinds of infections and cancers, such as pneumocystis pneumonia (PCP) a type of pneumonia, Kaposi sarcoma (KS) a type of cancer that affects the skin and internal organs, wasting syndrome (involuntary weight loss), memory impairment, or tuberculosis.
Even without one of these infections, a person is diagnosed with AIDS if their immune system weakens, as indicated by the number of CD4 cells. People with a low CD4 count need to take certain medications to prevent opportunistic infections. But, again, most people with HIV will not develop AIDS if they get and stay on treatment.
How is HIV spread?
HIV is spread mostly through four body fluids:
- vaginal fluid
- breast milk
HIV is NOT spread through saliva, tears, sweat, feces or urine.
How is HIV spread through sex?
You can get infected from sexual contact with someone who has HIV. Sexual contact that can transmit HIV includes:
- vaginal sex (penis in the vagina)
- anal sex (penis in the anus of either a man or a woman)
- oral sex (penis in the mouth)
If you have sex, the best way to prevent HIV infection is practicing "safer sex" with any partner who is not proven to be HIV negative (on recent testing). Always use protection. This could include using a condom, dental dam, or other latex barrier, and/or PrEP (pre-exposure prophylaxis, a daily medication taken daily to prevent HIV). It is also important to avoid "rough sex" or other activities that might cause bleeding. Use water-based lube; oil-based lube causes latex condoms to break. See more tips for using condoms. HIV post-exposure prophylaxis (PEP) is medication taken within 72 hours after a recent possible exposure to HIV. It should be used only in emergency situations.
How is HIV spread through blood?
You can become infected if you have contact with the blood of someone who has HIV. For example:
- sharing injection equipment when using drugs
- getting tattoos or body piercings with unsterilized needles
- accidental needle sticks
If you inject drugs, use new or sterilized injection equipment every time. Some VA facilities have programs to provide clean equipment. You can also take PrEP to lower your risk.
Can HIV pass from pregnant people to their babies?
Infection can pass from pregnant people with HIV to their babies in the womb and during birth. Taking HIV medications during pregnancy and childbirth dramatically lowers the risk of a baby becoming infected with HIV. Learn more about pregnancy and HIV.
Does HIV have symptoms?
The period early infection is called acute HIV infection. Symptoms can be different for each person. Sometimes there are no symptoms at all. Others may feel as if they have a cold or the flu. Symptoms can include:
- sore throat
- swollen lymph nodes, usually on the neck
- sores in the mouth
If symptoms appear, they usually do so within days or weeks after infection, and end after 1 to 2 weeks. The only way to tell if your symptoms are from a cold, the flu, or HIV is to get an HIV test.
What is HIV and viral hepatitis coinfection?
Coinfection is a medical term meaning that you have two or more infections in your body at the same time. If you have HIV and hepatitis C coinfection, for example, then you have both HIV and hepatitis C.
Hepatitis C can be cured with treatment, and all persons with HIV and hepatitis C coinfection should receive treatment for both infections. Learn more about viral hepatitis.
- HIV Testing
- HIV Treatment
HIV.gov provides access to Federal HIV information and resources.
Information on HIV in English and Spanish including prevention, treatment, and statistics.