Key takeaways
- WHO prefers a three-drug PEP regimen taken for 28 days.
- The usual combination is tenofovir plus lamivudine or emtricitabine, with dolutegravir as the third medicine.
- Other combinations are also accepted, so your pills may differ from someone else’s and still be correct.
- Some antacids and mineral supplements need to be spaced from dolutegravir.
- Your doctor prescribes the exact regimen and dose; take every tablet as labelled.
What is the standard PEP regimen for HIV?
The standard PEP regimen is a combination of three HIV medicines taken every day for 28 days, started as soon as possible after a possible exposure. The World Health Organization prefers tenofovir plus lamivudine (or emtricitabine) as the base, with dolutegravir as the third drug.
These are HIV treatment medicines, used here for a short course. For how PEP works and who needs it, see our guide to what PEP is and how the 28-day course works.
The three medicines in a typical PEP regimen
Each medicine in the combination blocks HIV at a different step, which is why three together work better than one.
- Tenofovir: one of the two “backbone” medicines.
- Lamivudine or emtricitabine: the second backbone medicine; the two are closely related.
- Dolutegravir: the third drug, from a group called integrase inhibitors.
WHO notes that a single tablet combining tenofovir, lamivudine and dolutegravir, often shortened to TLD, can also be used for PEP and may be preferable because it means fewer pills.
Preferred PEP regimen vs the alternatives
The WHO guidelines for HIV post-exposure prophylaxis set out a preferred combination and several accepted alternatives.
WHO-recommended PEP medicines for adults and adolescents
| Part of the regimen | What WHO recommends | What it means for you |
|---|---|---|
| Backbone (two drugs) | Tenofovir + lamivudine or emtricitabine | Almost everyone gets this pair |
| Preferred third drug | Dolutegravir | The usual first choice |
| Alternative third drugs | Atazanavir/ritonavir, darunavir/ritonavir, lopinavir/ritonavir or raltegravir | Used when dolutegravir does not suit you |
| Single combined tablet | TLD (tenofovir, lamivudine, dolutegravir) | Fewer pills to remember |
| Two-drug regimen | Effective, but three drugs are preferred | Only if a third drug is not available yet |
WHO also notes that other HIV medicines are used for PEP in some high-income countries, which is why foreign websites may name different pills.
Why your PEP medicines may look different
Many people compare their pills with a friend’s or a forum post and worry. More than one combination can be the right choice.
Your doctor may choose a different combination if you have kidney problems, take medicines that interact, are pregnant or planning a pregnancy, or if the other person’s HIV treatment history is known. If you are unsure why you were given yours, ask.
How to take your PEP medicines each day
How well PEP works depends heavily on taking it correctly, as our guide to how effective PEP is and what helps it work explains. These habits help most people finish the course.
- Take the first dose as soon as possible, ideally within 24 hours and no later than 72 hours after the exposure.
- Take every dose at about the same time each day, exactly as your label says.
- Finish all 28 days, even if you feel well or the other person tests negative.
According to MedlinePlus drug information on dolutegravir, it can be taken with or without food. For a week-by-week view, see the 28-day PEP course from first dose to follow-up.
Once-daily vs twice-daily PEP schedules
Many PEP regimens are taken once a day, but some alternative combinations need a second daily dose. Your label tells you which applies to you.
| Question | Once-daily schedule | Twice-daily schedule |
|---|---|---|
| When to take it | Same time every day | Morning and evening |
| Easy habit to link it to | Breakfast or bedtime | Breakfast and dinner |
| Main risk | Forgetting a whole day | Missing the second dose |
| Helpful tool | One daily phone alarm | Two alarms and a pill box |
If you forget a tablet, take it when you remember unless it is nearly time for the next one, and never double up. Our guide on what to do if you miss a PEP dose covers late and missed doses in detail.
Supplements, antacids and other medicines with your PEP regimen
Dolutegravir can bind to minerals such as calcium, iron, magnesium and aluminium in the gut, which can reduce how much of it your body absorbs. The fix is usually timing.
Common interactions with dolutegravir and what to do
| Product | Why it matters | What to do |
|---|---|---|
| Antacids, laxatives or multivitamins with aluminium, magnesium or calcium | Can reduce absorption | Take 2 hours after or 6 hours before dolutegravir |
| Calcium or iron supplements | Can reduce absorption | Space them, or take together only if dolutegravir is taken with food |
| Sucralfate or buffered medicines | Can reduce absorption | Take 2 hours after or 6 hours before dolutegravir |
| St John’s wort and other herbal products | May affect how PEP works | Tell your doctor before starting |
| Prescription medicines | Some interact with PEP | Bring a list or photos of the packs |
If your regimen uses a different third drug, the rules may differ, so check with your doctor or pharmacist. Questions about drinking during the course are covered in our guide to alcohol and PEP.
PEP medicine side effects in brief
Modern PEP medicines are usually well tolerated, and any nausea, headache or tiredness tends to settle within the first week or two. Our guide to common PEP side effects and how to manage them explains what to expect.
A rash with fever, blistering, mouth sores or swelling of the face or throat needs urgent medical help. Contact your clinic straight away, and in an emergency in Thailand call 1669.
Getting a PEP regimen in Bangkok
At HIV PEP Bangkok, near BTS Asok and MRT Sukhumvit, you can walk in for PEP any day from 09:00 to 21:00. An English- or Thai-speaking doctor assesses you in a private room and runs baseline tests.
Most people take their first dose at the clinic within about an hour and leave with the full 28-day supply, plus a medical letter naming the medicines for your own doctor.
If you are still deciding whether your exposure needs PEP, the PEP self-check and 72-hour window calculator can help. Our step-by-step plan after a possible HIV exposure covers the first hours.
After your PEP medicines: what comes next
After the last tablet you still need follow-up HIV tests, usually around 4 to 6 weeks and again at about 3 months after the exposure; our guide to testing for HIV after finishing PEP explains the timing.
If you often need PEP, ask about daily prevention; our comparison of the differences between PEP and PrEP is a good place to start.
Frequently asked questions about PEP medicines
My PEP pills look different from what a friend was given. Is that a problem?
Usually not. Several combinations are accepted, and doctors choose based on your health and other medicines. If you are unsure, ask your clinic to explain your regimen.
Is a two-drug PEP regimen good enough?
WHO says two drugs can be effective, but three are preferred. If only two are available at first, start them straight away and add the third as soon as it is available.
Should I take my PEP tablets with food?
Dolutegravir can be taken with or without food. Follow your label for the other medicines in your combination.
Does hepatitis B change which PEP medicines I can take?
WHO states that hepatitis B does not rule out PEP containing tenofovir, lamivudine or emtricitabine. If you have hepatitis B, your doctor will plan monitoring for when the course ends.
You do not need to know the drug names in advance. Contact our Bangkok clinic by LINE, WhatsApp or phone, or simply walk in, and a doctor will prescribe the right regimen for you.
