References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Seroconversion is the period shortly after HIV infection when the body begins producing antibodies to the virus. Around 70-80% of people experience an illness during this time, sometimes called “acute retroviral syndrome” or “HIV seroconversion illness.” The symptoms can be easily mistaken for flu or glandular fever, and many people don’t recognise them as a possible sign of HIV.
Here’s what to watch for.
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When Does Seroconversion Happen?
Seroconversion symptoms typically appear 2-4 weeks after infection and last 1-2 weeks. Some people have no symptoms at all. The timing matters because during this period viral load is very high, making the person particularly infectious — even before HIV tests can detect the infection.
Common Symptoms
| Symptom | How Often |
|---|---|
| Fever | Very common |
| Sore throat | Common |
| Body rash (often on trunk) | Common |
| Swollen lymph nodes | Common |
| Headache | Common |
| Muscle and joint pain | Common |
| Fatigue | Common |
| Mouth ulcers | Moderate |
| Night sweats | Moderate |
| Diarrhoea | Moderate |
Not everyone has every symptom. The combination of fever, rash, sore throat and swollen glands in someone who has had a recent risky exposure should raise suspicion.
What to Do If You Suspect Seroconversion
- Contact a sexual health clinic promptly — say you think you may have recent HIV
- Ask for a 4th-generation lab test (antibody + antigen)
- A very high-sensitivity viral load (RNA) test may be offered for earlier detection
- Consider PEP if the exposure was within the last 72 hours
- Avoid condomless sex until you have a confirmed result
Why Early Detection Matters
- Starting treatment immediately protects your long-term health
- Acute HIV infection carries a very high viral load and high transmission risk
- Early treatment reduces the size of the HIV reservoir
- Knowing your status protects current and future partners
Read more: How do I know if I have HIV? | HIV window period | What is HIV?
Frequently Asked Questions
Can I have HIV without seroconversion symptoms?
Yes. Around 20-30% of people have no symptoms during seroconversion. The only reliable way to know is to test.
Do seroconversion symptoms prove I have HIV?
No. Flu, glandular fever and many other illnesses cause similar symptoms. Testing is the only way to confirm.
How soon after exposure can tests detect HIV?
A 4th-generation lab test is reliable from about 4 weeks after exposure. Viral load tests can detect HIV even earlier, sometimes within 10-14 days.
Related reading
- Abnormal Genital Discharge and Chlamydia
- Injectable HIV Treatment: Everything You Need to Know
- Are HIV Tests Accurate If You're on PrEP, PEP or ART?
- Asymptomatic STIs: Silent Infections Explained
- Causes of Painful Sex and How to Treat It
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
