PEP in Chiang Mai: what to do after possible HIV exposure
If you have had a possible HIV exposure, do not wait. PEP is time-sensitive — ideally started within hours. This guide explains what to do, what to bring, and when to go to hospital instead.
Quick answer
PEP (post-exposure prophylaxis) is an antiretroviral medication course taken after a possible HIV exposure. It must be started as soon as possible — ideally within a few hours and generally no later than 72 hours after the possible exposure. A doctor assessment is required before PEP can be started. If you think you may need PEP and it is outside clinic opening hours, go directly to a hospital or emergency department. Do not wait.
What is PEP and how does it work?
PEP stands for Post-Exposure Prophylaxis. It is a short course of antiretroviral medication taken after a possible HIV exposure to reduce the risk of HIV transmission.
PEP works by blocking HIV from establishing a permanent infection in the body after a possible exposure. For PEP to be effective:
- It must be started as soon as possible after the exposure — ideally within a few hours
- It is generally considered appropriate up to 72 hours (3 days) after a possible exposure
- The full course must be completed — PEP is usually taken daily for approximately 28 days
- Adherence (not missing doses) is important for PEP to work as well as possible
PEP is not a guarantee. When started promptly and completed correctly, it can significantly reduce HIV risk after a possible exposure. It is not 100% effective, and it does not protect against STIs other than HIV.
Seek assessment as soon as possible
Seek prompt assessment even if:
- Waiting to see if symptoms develop — many people with HIV have no symptoms; this is not a reliable guide
- Waiting to find out the HIV status of a source person — assessment can begin while this is being determined
- Waiting for a more convenient time — every hour matters for PEP effectiveness
- Thinking the risk was low — let a doctor assess the risk, not just your own judgment
If your possible exposure was within the last 72 hours, seek medical assessment now. Outside clinic opening hours, hospital or emergency department assessment may be the fastest option for time-sensitive PEP care. Tell them you need assessment for PEP after a possible HIV exposure.
When hospital care is the safest option
Go directly to hospital or emergency department if:
- You experienced a sexual assault — hospital care is needed for comprehensive support, forensic documentation, PEP assessment, and referral to specialist services
- You have severe injury, bleeding, or distress related to the situation
- You feel unsafe or are in an emergency situation
- You are unsure whether the exposure warrants PEP and the clinic cannot be reached
What happens at the clinic during PEP assessment
When you come to Klaibaan Clinic for PEP assessment, the doctor will:
- Take a brief history: the doctor will ask about the timing of the possible exposure, the type of exposure, and any known information about the source person's HIV status if relevant. This is handled respectfully and without judgment.
- Assess whether PEP may be appropriate: not every possible exposure results in PEP being recommended. The doctor will assess the risk based on the type of exposure, the timing, and other clinical factors.
- Arrange baseline tests: a baseline HIV test is required before PEP can be started. Other tests — kidney function, hepatitis B — may also be arranged.
- Explain the medication and follow-up: if PEP is considered appropriate, the doctor will explain what the medication is, how to take it, the importance of completing the full course, possible side effects, and when to return for follow-up HIV testing.
PEP assessment is available at Klaibaan Medical Clinic during opening hours (Mon–Fri 17:00–20:00, Saturday 13:00–17:00). If your exposure was outside these hours, go directly to a hospital rather than waiting.
What to bring
- Passport or Thai ID: required for registration.
- Information about the exposure: when it occurred (date and approximate time), what type of exposure it was, and any information about the source person's HIV status if known.
- Current medicines and allergies: some antiretroviral medications interact with other drugs. Telling the doctor about all current medications and any known allergies helps ensure the right choices are made.
- Previous HIV or STI test results: if you have been tested for HIV before, bring the results if available. This helps establish your baseline status before starting PEP.
- Hepatitis status if known: hepatitis B co-infection affects medication choices for PEP. If you know your hepatitis B status or vaccine history, share it.
After completing PEP: what to expect
After completing the 28-day PEP course:
- Follow-up HIV testing is required. A follow-up HIV test is recommended at specific intervals after completing PEP — the doctor will advise on timing. This is important to confirm the outcome of the PEP course.
- STI testing may be appropriate. The circumstances of the original exposure may also warrant STI screening (syphilis, gonorrhea, chlamydia) — the doctor can advise.
- Discuss ongoing prevention. If the circumstances that led to this PEP episode may recur, it is worth discussing longer-term prevention with the doctor. PrEP may be a more appropriate approach for ongoing prevention rather than relying on PEP after each exposure.
PEP is not intended for repeated use as a routine HIV prevention strategy. If you find yourself needing PEP repeatedly, the doctor may discuss PrEP as a more appropriate long-term approach.
How Klaibaan Clinic can help
Klaibaan Medical Clinic in San Sai, Chiang Mai provides PEP consultation for English-speaking patients when within the clinic’s outpatient services and timing. The clinic can:
- Assess whether PEP may be appropriate based on timing and exposure type
- Arrange baseline HIV testing and other relevant tests
- Explain the medication course, dosing schedule, and follow-up requirements
- Arrange follow-up testing after PEP completion
- Discuss PrEP as an ongoing prevention option after PEP is completed
You can contact the clinic on LINE before visiting if you have questions about preparation or whether PEP may be appropriate. For urgent situations outside opening hours, go directly to a hospital for timely assessment.
Common questions
How quickly do I need to start PEP after a possible HIV exposure?
PEP should be assessed as soon as possible after a possible HIV exposure. It is generally most effective when started promptly — ideally within a few hours. PEP is typically not recommended after 72 hours (3 days) from the possible exposure. Do not rely on symptoms; seek medical assessment promptly.
What happens at the clinic when I come for PEP assessment?
The doctor will ask about the timing and type of possible exposure, perform a brief assessment, and arrange baseline HIV testing and other relevant tests. If PEP is considered appropriate, the doctor will explain the medication, the duration of the course, the importance of completing it, and follow-up testing requirements. Not every possible exposure will result in PEP being recommended — the doctor will assess what is appropriate for your specific situation.
What if I need PEP outside clinic opening hours?
If you need PEP assessment outside clinic opening hours, go directly to the nearest hospital or emergency department and explain that you need assessment after a recent possible HIV exposure. PEP is time-sensitive.
Is PEP a guarantee that I will not acquire HIV?
No. When taken correctly, promptly, and for the full course, PEP can significantly reduce the risk of HIV transmission. However, it is not 100% effective. Adherence to the full 28-day course without interruption is important. Follow-up HIV testing after completing PEP is also required to confirm the outcome.
Should I consider PrEP after taking PEP?
If you have taken PEP after a possible exposure, it may be appropriate to discuss PrEP with a doctor as an ongoing prevention strategy. PrEP is planned prevention taken before exposure rather than after. The doctor can discuss whether PrEP is suitable for your situation after PEP is completed and follow-up testing is done.
Sources and related reading
Selected official sources and clinic pages used to keep this guide practical and medically responsible.
Need urgent PEP assessment?
If your possible exposure was within the last 72 hours, contact Klaibaan Clinic on LINE or call now. Outside clinic opening hours, hospital or emergency department assessment may be the fastest option for time-sensitive PEP care. The clinic provides English-friendly PEP consultation in San Sai, Chiang Mai.