When should I get an HIV test after potential exposure?

HIV Testing After Potential Exposure

HIV testing should be performed at baseline (immediately after exposure), 6 weeks, 12 weeks, and 6 months post-exposure, with 4th generation tests preferred due to their earlier detection capability. 1, 2

Recommended Testing Schedule

• Baseline (Day 0): Immediate testing after exposure to establish baseline status
• 6 weeks post-exposure: First follow-up test (can detect most infections with 4th generation tests)
• 12 weeks post-exposure: Second follow-up test
• 6 months post-exposure: Final conclusive test, especially after PEP

This testing schedule is based on the most recent CDC recommendations from 2025, which provide the most comprehensive guidance for HIV testing following potential exposure 1, 2.

Test Types and Window Periods

• 4th generation tests (preferred): Detect both HIV antibodies and p24 antigen

  • Window period: 14-21 days
  • Can detect most infections by 2-4 weeks post-exposure 2

• 3rd generation tests: Detect only HIV antibodies

  • Window period: 21-28 days
  • Less sensitive in early infection 2

Special Considerations

Post-Exposure Prophylaxis (PEP)

If you received PEP after exposure, it's particularly important to complete the full testing schedule through 6 months, as PEP may delay seroconversion and extend the window period for antibody detection 2.

Early Detection vs. Conclusive Results

• A negative 4th generation test at 9 weeks (64 days) post-exposure is generally considered conclusive
• However, following the complete testing schedule (through 6 months) is recommended for maximum certainty, especially after PEP 2

Acute HIV Infection

During early infection (first few weeks), viral loads are typically much higher than in later stages, making this period both highly infectious and important for early diagnosis 3. Symptoms of acute HIV infection may include:

• Fever
• Rash
• Lymphadenopathy
• Sore throat
• Myalgia/arthralgia

Common Pitfalls to Avoid

1. Stopping testing too early: A single negative test at 41 days is insufficient to rule out infection 2
2. Using outdated testing algorithms: Older recommendations suggested testing only at 3 months; current guidelines recommend multiple time points 1, 2
3. Relying solely on 3rd generation tests: These miss early infections that 4th generation tests can detect 2, 4
4. Ignoring the need for confirmatory testing: Positive screening tests require confirmation with more specific tests 2
5. Extending testing beyond necessary timeframes: Testing beyond 6 months without specific indications increases anxiety without medical benefit 2

Next Steps After Testing

If any test is positive:

• Confirmatory testing should be performed
• If confirmed positive, prompt linkage to HIV care is essential for early treatment
• Early treatment improves long-term outcomes and reduces transmission risk

If all tests remain negative through 6 months:

• HIV infection can be confidently ruled out
• Consider PrEP (pre-exposure prophylaxis) if ongoing risk factors exist

Following this evidence-based testing schedule provides the optimal balance between early detection and conclusive results, maximizing both individual health outcomes and public health benefits.