HIV: symptoms, testing, treatment and how to tell your partner
HIV is the human immunodeficiency virus. Today there is no cure, but there is very effective treatment: people with HIV who take it have a life expectancy similar to everyone else and, if the virus is undetectable, they do not pass it on through sex. If you have had a risky encounter in the last 72 hours, read the section on PEP first.
What is HIV?
It is a virus that attacks immune system cells (CD4 lymphocytes) and, without treatment, gradually destroys them, so the body loses its ability to defend itself. When the immune system is very weak and serious infections or tumors appear, it is called AIDS, the advanced stage of the infection. With treatment, that stage is avoided.
HIV symptoms
Between 2 and 4 weeks after infection, some people have a flu-like illness: fever, tiredness, sore throat, muscle aches, a skin rash or swollen glands. Others notice nothing. After that, the infection can go years without symptoms while the virus keeps damaging the immune system. That is why the only way to know if you have HIV is to get tested.
How is HIV transmitted?
It is transmitted through the blood, semen, pre-seminal fluid, vaginal and rectal fluids and breast milk of a person whose virus is detectable:
- Anal or vaginal sex without a condom.
- Sharing syringes or other injection equipment.
- From mother to baby during pregnancy, childbirth or breastfeeding, which treatment almost completely prevents.
It is not transmitted by kissing, hugging, saliva, sweat, mosquito bites, or by sharing glasses, cutlery, the bathroom or a swimming pool.
PEP: what to do after a risky encounter
If you have had sex without a condom, or the condom broke, with someone who may have HIV, go to a hospital emergency department as soon as possible. There they will assess whether you need post-exposure prophylaxis (PEP): a 28-day treatment that greatly reduces the risk of infection. It must be started within the first 72 hours, and the sooner the better.
The HIV test
You can get tested by your doctor, at sexual health clinics, at community organizations and at some pharmacies, and there is also an HIV self-test sold in pharmacies without a prescription. Keep in mind the window period, that is, the time it takes for the test to detect the infection:
- Fourth-generation lab tests detect most infections from 6 weeks.
- Tests that only detect antibodies, such as many rapid tests and self-tests, may need up to 3 months.
A positive result on a rapid test or a self-test must be confirmed in a laboratory.
HIV treatment
Antiretroviral treatment means taking medication, usually one pill a day, for life. It controls the virus, lets the immune system recover and prevents AIDS.
How to tell your partner you have HIV
Telling your partner allows them to get tested and, if the result is negative, to protect themselves with PrEP or condoms. Some tips:
- Prepare yourself: if you can, do it after talking to your doctor, so you can explain the treatment and what undetectable means.
- Choose a calm, private moment. Many community organizations and HIV units offer support for this step.
- Give clear information: HIV can be treated, with an undetectable viral load it is not passed on through sex, and PrEP exists.
- Ask them to get tested and, if the contact was in the last 72 hours, to go to an emergency department to be assessed for PEP.
- Respect their pace: they may need a few days to take it in.
If you cannot tell an ex or a casual partner in person, you can ask your HIV unit for help or send them an anonymous text message or email with STI notice, without your name or number appearing. Sharing your diagnosis is a personal decision, but notifying the people who may have been exposed allows them to get tested in time.
Who should you notify?
It depends on when the infection may have happened. Ideally, notify the sexual partners you have had since your last negative test and anyone you have shared injection equipment with. If you had never been tested before, your healthcare team will help you work out how far back to go.
If you have been told you might have HIV
If the risky contact was less than 72 hours ago, go to an emergency department to be assessed for PEP. If it was earlier, get tested now and repeat the test once the window period has passed: 6 weeks with a fourth-generation lab test or 3 months with a rapid test. In the meantime, use condoms. If the result is negative and you are at risk, ask about PrEP.
How to prevent HIV: condoms and PrEP
Condoms protect against HIV and other STIs. PrEP (pre-exposure prophylaxis) is a medication that, taken correctly, reduces the risk of getting HIV through sex by about 99%. PrEP does not protect against other STIs.
Frequently asked questions about HIV
Can HIV be transmitted through oral sex?
It is possible, but the risk is very low, much lower than with anal or vaginal sex without a condom. A condom or a latex barrier lowers it even further.
What does undetectable = untransmittable mean?
It means that a person with HIV who takes their treatment and keeps an undetectable viral load for at least 6 months does not pass the virus on through sex. This is backed by large studies involving thousands of couples.
Other sexually transmitted infections
Syphilis · Gonorrhea · Genital herpes · Pubic lice (crabs) · HPV and genital warts · Chlamydia · Yeast infection (candidiasis) · Hepatitis A, B and C · Trichomoniasis · Scabies · Mpox (monkeypox)
Sources: CDC: about HIV; CDC: HIV testing.Health information updated in October 2026. It does not replace advice from a healthcare professional.