Quick read
Key points
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HIV (human immunodeficiency virus) is a virus that attacks the immune system, and if untreated, can eventually progress to AIDS, a stage where the immune system is severely weakened. However, with modern antiretroviral treatment, people with HIV can live long, healthy lives, and effective treatment reduces the virus to undetectable levels, meaning it cannot be transmitted to others (undetectable = untransmittable).
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Topic-specific prevention and risk reduction will be added during the article-specific evidence audit.
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You've had unprotected sex with a partner whose HIV status you're unsure of
01 · Know
What is HIV?
HIV (human immunodeficiency virus) is a virus that attacks the immune system, and if untreated, can eventually progress to AIDS, a stage where the immune system is severely weakened. However, with modern antiretroviral treatment, people with HIV can live long, healthy lives, and effective treatment reduces the virus to undetectable levels, meaning it cannot be transmitted to others (undetectable = untransmittable).
HIV is transmitted through specific bodily fluids, primarily through unprotected sex or sharing needles, not through everyday contact. Early diagnosis through testing and prompt treatment lead to the best long-term health outcomes.
02 · Understand
Clinical context
Undetectable equals untransmittable (U=U)
People with HIV who take effective antiretroviral treatment and maintain an undetectable viral load cannot transmit HIV to sexual partners — this is a well-established scientific fact that has transformed understanding of living with HIV.
03 · Act
When to Get Tested
- 1You've had unprotected sex with a partner whose HIV status you're unsure of
- 2You'd like routine sexual health screening, which typically includes HIV testing
- 3You believe you may have been exposed to HIV — PEP (post-exposure prophylaxis) may be available if started promptly
- 4You're considering PrEP (pre-exposure prophylaxis) to reduce your risk of acquiring HIV
04 · Prevent & manage
Practical steps
PEP Needs to Start Within 72 Hours of Possible Exposure
If you believe you've been exposed to HIV, post-exposure prophylaxis (PEP) can significantly reduce the risk of infection, but needs to be started as soon as possible, and always within 72 hours — seek emergency or sexual health services promptly.
- 1Get tested regularly if at risk.Regular testing is recommended for anyone with new or multiple partners, or other risk factors.
- 2Seek PEP promptly after possible exposure.This needs to start within 72 hours to be effective, so don't delay seeking care.
- 3Take antiretroviral treatment consistently if diagnosed.This allows most people with HIV to live long, healthy lives and reach an undetectable viral load.
- 4Consider PrEP if you're at ongoing risk.This medication significantly reduces the risk of acquiring HIV for people at higher risk.
- 5Attend regular monitoring appointments if diagnosed.This tracks your treatment's effectiveness and overall health.
Evidence
References
BarnMD Health Intelligence uses authoritative and clinically relevant sources appropriate to the topic. References are shown so readers can inspect the evidence directly.
- HSE: HIV ↗
Medical information notice
Health education, not individual medical advice
BarnMD Health Library provides general health education for public health literacy. Reading this article does not establish a doctor-patient relationship and this information is not a diagnosis, prescription, or personalised treatment plan. If you have symptoms or concerns about your health, seek appropriate advice from a qualified healthcare professional. If you develop emergency warning signs, seek urgent or emergency medical attention.
BarnMD Bottom Line
HIV is a manageable long-term condition with modern treatment, and people on effective treatment with an undetectable viral load cannot transmit the virus to others.
If you believe you've been exposed to HIV, seek PEP promptly — it needs to start within 72 hours to be effective.