If it happened in the last 72 hours, act on that first. If your partner has HIV and isn’t on effective treatment, or you don’t know their status, ask about PEP (post-exposure prophylaxis) today. It must start within 72 hours. How to get PEP

You’re not overreacting, but the numbers are on your side

Feeling scared after a condom slips, a one-night stand or a needle injury is a normal reaction. HIV is a serious word. But the fear usually runs well ahead of the actual risk, and it helps to look at real numbers.

These are the calculator’s estimates for a single act, based on CDC data:

  • Oral sex with a partner who has HIV and isn’t on treatment: 0.01% (about 1 in 10,000)
  • Vaginal sex without a condom, a man with a woman of unknown status in the US: <0.0001% (about 1 in 1,500,000)
  • The same, with a condom: <0.0001% (about 1 in 7,300,000)
  • Receptive anal sex without a condom with a partner who has HIV and isn’t on treatment, the highest-risk sexual exposure: 1.4% (about 1 in 72)

If a partner with HIV is on treatment and has an undetectable viral load, they don’t pass HIV on through sex. See U=U.

Some worries carry no risk at all. HIV isn’t spread by saliva, sweat, tears, kissing, hugging, sharing food or drinks, toilet seats, insects or contact with unbroken skin. More in how HIV is not transmitted.

Testing is the way out

Worry feeds on uncertainty. A test at the right time removes it. Once you’re past a test’s window period, a negative result means you don’t have HIV from that exposure, as long as you haven’t had another exposure since.

  • A lab antigen/antibody test (blood from a vein) is conclusive from day 45.
  • A NAT (nucleic acid test) is conclusive from day 33.
  • A rapid antigen/antibody test (finger-prick) and antibody tests, including most home self-tests, are conclusive from day 90.

If you took PEP, follow your clinician’s testing plan instead. CDC recommends tests about 4 to 6 weeks and 12 weeks after the exposure.

Testing earlier can help too. A negative result partway through the window already lowers the estimate a lot. For receptive anal sex with a partner who has HIV and isn’t on treatment, a negative lab test at four weeks takes it to 0.18% (about 1 in 540). See HIV test accuracy by week to plan yours.

Once you have a conclusive negative, testing again for the same exposure won’t change the answer. If you notice the urge to keep retesting, that is the worry talking, not the facts.

Why your body feels like it’s sending signals

Anxiety causes real physical symptoms. The NHS lists a more noticeable or unusual heartbeat, stomach problems, feeling tense, getting tired easily, feeling dizzy or lightheaded, and trouble sleeping. After an exposure, it’s natural to read each of these as a sign of HIV.

Symptoms can’t diagnose HIV in either direction. Many people with HIV have none early on, and the flu-like symptoms some people get are often caused by other illnesses. A test is the only way to know. See early HIV symptoms.

Things that help while you wait

  • Set your test date and put it in your calendar. Then you don’t have to decide again every day.
  • Limit searching. Reading forums and symptom lists late at night rarely brings relief. One reliable source is enough.
  • Talk to someone. A friend, a sexual health clinic or a helpline. Clinic staff are used to these questions.
  • Look after the basics. Regular sleep and meals make a hard few weeks easier to get through.
  • Think ahead. If you’re likely to be exposed again, ask about PrEP (pre-exposure prophylaxis). Taken as prescribed, it lowers the risk from sex by about 99% for anal sex and about 90% for vaginal sex.

When to get mental-health support

Get help if the worry carries on after a conclusive negative test, or if it’s affecting your sleep, work or relationships. A doctor can help, and talking therapies are one option. In England, adults registered with a GP can refer themselves to NHS talking therapies for anxiety without seeing the GP first.

If you’re in crisis or thinking about harming yourself, get help now. In the US, call or text 988, or chat at 988lifeline.org. It’s free, confidential and open 24/7, for any kind of emotional distress. Elsewhere, call your local emergency number or a crisis line.

What to do now

  1. Under 72 hours since the exposure? Ask about PEP first.
  2. Check your actual risk with the calculator.
  3. Pick a test and a date based on its window period.
  4. Retest once after the window if your first test was inside it, or follow your PEP testing plan, then stop.
  5. Get support if the worry doesn’t ease after a conclusive result.