Human immunodeficiency virus, or HIV, attacks the body’s infection-fighting immune system. Without treatment, HIV can lead to AIDS (acquired immunodeficiency syndrome). At the start of the AIDS epidemic in the 1980s, people who were infected with HIV quickly progressed to serious disease. But today’s treatments help lower the amount of virus in the blood—so people who are HIV-positive can live healthier, longer lives and not necessarily progress to AIDS.

More than one million people in the US live with HIV, and scarily, one in seven of them don’t know they have it. HIV symptoms can be hard to detect. Within a month or two of HIV entering the body, 40% to 90% of people experience flu-like symptoms known as acute retroviral syndrome (ARS). But sometimes HIV symptoms don't appear for years—or even a decade—after infection.

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"In the early stages of HIV infection, the most common symptoms are none," Michael Horberg, MD, director of HIV/AIDS for Kaiser Permanente, in Oakland, California, tells Health. As many as one in five people in the United States with HIV doesn't know they have it, according to the Centers for Disease Control (CDC). That's why it's so important to get tested, especially if you currently have or have had unprotected sex with more than one partner or use intravenous drugs.



HIV symptoms for women and for men are often the same; here are 16 of the most common signs.