How soon after exposure to unprotected sex can you test for Human Immunodeficiency Virus (HIV)?

HIV Testing Timeline After Unprotected Sexual Exposure

HIV testing should be performed at baseline (immediately after exposure), at 4-6 weeks, and at 12 weeks after potential exposure to HIV through unprotected sex. 1

Initial Testing (Baseline)

• A rapid HIV test or laboratory-based antigen/antibody combination test should be performed as soon as possible after the potential exposure 1
• This baseline testing helps determine if the person already had HIV infection prior to the exposure 1
• If rapid tests are not available, treatment decisions should be made assuming the person is not infected, pending test results 1

Follow-Up Testing Schedule

• Interim HIV testing should be performed 4-6 weeks after exposure using both:
  • Laboratory-based HIV antigen/antibody test
  • HIV nucleic acid test (NAT) 1
• Final HIV testing should be conducted at 12 weeks after exposure using:
  • Laboratory-based HIV antigen/antibody combination immunoassay
  • Diagnostic HIV nucleic acid test 1

Special Considerations

• For individuals who started post-exposure prophylaxis (PEP) within 24 hours of exposure and did not miss any doses, the 4-6 week testing may be deferred 1
• For persons with recent exposure to long-acting injectable PrEP medications, diagnostic HIV nucleic acid testing is recommended at the initial evaluation in addition to antibody testing 1

Post-Exposure Prophylaxis (PEP) Considerations

• If the exposure occurred within 72 hours, PEP should be considered and initiated as soon as possible 1
• PEP is a 28-day course of antiretroviral medications 1
• PEP is less likely to be effective if started more than 72 hours after exposure 1
• Patients on PEP should be monitored for medication side effects and adherence 1

Important Caveats

• The window period (time between HIV infection and when it can be detected by tests) varies depending on the type of test used 1
• Patients should be counseled about signs and symptoms of acute HIV infection (especially fever and rash) and advised to return for evaluation if these occur 1
• Patients should practice protective behaviors (abstinence or consistent condom use) throughout the testing period to prevent potential transmission to others 1
• Limited awareness of proper PEP timing remains a significant barrier to effective HIV prevention, with only 24% of at-risk individuals aware of the correct timing for effective PEP treatment 2

Additional Testing Recommendations

• Testing for other sexually transmitted infections, hepatitis B and C, and pregnancy (if applicable) should be offered at the time of HIV testing 1
• For individuals with ongoing risk behaviors, transition to pre-exposure prophylaxis (PrEP) should be considered after completing the testing period 1