More than 1 million people in the United States live with HIV, and about 1 in 7 of them don't know they have it. Early symptoms of HIV, such as fever, tiredness, and rash, are similar to many other common infections like the flu. It's important to know that having a couple of symptoms that look like HIV doesn't guarantee you have it. If there's a chance you could have HIV because you had unprotected sex or shared a needle, the only way to know for sure is to get tested. Early symptoms of HIV appear within 2 to 4 weeks after infection and can include fever, chills, muscle aches, tiredness, swollen glands, and a sore throat. These symptoms can also be caused by other viral and bacterial infections. A rash, like the one seen in early HIV infection, could have many possible causes. Diarrhea could come from a stomach virus or food poisoning, and mouth sores could be from a burn, oral herpes, a food sensitivity, an allergy, or a vitamin deficiency. After these symptoms improve, HIV enters a stage where the virus is still in your body but you have no symptoms. This stage can last up to 15 years. Without treatment, HIV can progress to AIDS, where the immune system is so weak that many infections can occur, causing symptoms like fever, night sweats, extreme fatigue, and swollen glands. These symptoms can also happen with other conditions. A fever usually means your immune system is fighting an infection, and many illnesses can cause a fever. Night sweats, extreme tiredness, and swollen glands can also be caused by other conditions. Rapid weight loss, diarrhea lasting more than a week, and sores on the mouth, penis, vagina, or anus could also have other causes. Red, brown, pink, or purple blotches on the skin can be caused by other conditions as well. Symptoms alone can't confirm or rule out HIV; the only way to know for sure is to get tested. You can get an HIV test from your doctor or at a clinic. Some tests can detect HIV as early as 10 days after exposure, while others may take months to show a positive result. If you think you might have HIV, see your doctor for advice.