You can take PrEP and hormones together: studies show gender-affirming hormone therapy does not meaningfully weaken oral PrEP, and PrEP does not lower your hormone levels, although trans women on estradiol should take PrEP every day rather than using 2-1-1.
Worry about interactions is one of the most common reasons trans people delay starting PrEP. That worry is understandable, because hormones are central to how you live and feel. This guide sets out what the research shows, which schedule fits your body and the sex you have, and what to keep an eye on.
Do PrEP and your hormones affect each other?
There are two separate questions here. Does PrEP change your hormone levels? And do hormones change how much PrEP medicine reaches the places it needs to protect? Much of the best evidence comes from studies run in Bangkok.
On the first question, the answer is reassuring. In the studies, estradiol levels stayed the same once PrEP was added. The Liverpool HIV interactions database lists estradiol with tenofovir and emtricitabine as an interaction that is not expected, based on research in trans women.
What the main studies found
| Study | PrEP studied | Main finding |
|---|---|---|
| iFACT (Thailand) | TDF/FTC, the usual Thai tablet | Hormones lowered tenofovir levels modestly; estradiol unchanged |
| iFACT-3 (Thailand) | TAF-based PrEP | No significant interaction either way |
| US daily-dosing study | TDF/FTC, observed doses | Drug levels similar in trans women, trans men and cis men |
With daily dosing, the modest drop seen in the first iFACT study still leaves protective drug levels, but it leaves little margin for error on a schedule built around just a few pills.
The later iFACT-3 study looked at the newer TAF-based tablet and found no meaningful change in either direction. Most people in Thailand take the older TDF/FTC tablet, so the daily-dosing advice below still applies.
Trans women: why daily PrEP rather than 2-1-1
The 2-1-1 schedule means two pills 2–24 hours before sex, then one pill 24 hours and one pill 48 hours after the first dose. It works well for cis men who have sex with men and for trans women who are not taking estradiol-based hormones.
Questions about on-demand PrEP for transgender women come up often. If you take estradiol, guidelines advise against 2-1-1, because the slightly lower drug levels have not been proven enough for short courses. Daily PrEP gives maximum protection after about 7 days for receptive anal sex.
- Taking estradiol: daily PrEP.
- Not taking estradiol: daily PrEP or 2-1-1, provided you do not have hepatitis B.
- After vaginoplasty: talk to a doctor, as there is little research on PrEP levels in neovaginal tissue.
If you are eligible for 2-1-1, our 2-1-1 dose timing tool works out each pill for you.
Trans men and non-binary people
PrEP for trans men follows the same principle: no interaction is expected between testosterone and the usual PrEP tablet, and daily dosing is the recommended schedule. If you have receptive front-hole sex, allow about 21 days of daily pills before relying on PrEP, because protective levels build more slowly in that tissue.
Testosterone does not reliably prevent pregnancy, and PrEP does not either. If pregnancy is possible, contraception is a separate conversation. Our guide to PrEP for women and front-hole sex covers the 21-day lead-in in more detail.
For non-binary people, the right schedule depends on your body, any hormones you take and the kind of sex you have, not on a label. A doctor can match the plan to your situation without you needing to explain more than you want to.
Choosing a schedule by situation
| Situation | Suggested schedule | Time to full protection |
|---|---|---|
| Trans woman on estradiol, anal sex | Daily | About 7 days |
| Trans woman not on estradiol | Daily or 2-1-1 | 7 days daily; 2-1-1 from the first double dose |
| Trans man, receptive front-hole sex | Daily | About 21 days |
| Trans man, anal sex only | Daily | About 7 days |
What to keep an eye on while on both
Taking PrEP and hormones side by side mainly means sensible monitoring, not extra restrictions. Tenofovir is cleared through the kidneys, so you will have kidney tests before starting and at regular check-ups. Some anti-androgens, such as spironolactone, also act on the kidneys, so it helps when both prescribers see your results.
- Keep taking your hormones exactly as before; there is no need to pause them.
- Tell your hormone prescriber you are on PrEP, and tell us which hormones you use, including any bought without a prescription.
- Mention gym supplements or injectable hormones you source yourself, as these can affect test results.
The routine tests for people on PrEP include HIV, kidney and hepatitis B checks. Hepatitis B matters because stopping TDF/FTC suddenly can cause a flare in people who have it, which is also why 2-1-1 is not used in that case.
Long-acting options for trans people
If daily tablets are hard to fit around your life, longer-acting PrEP may appeal. Twice-yearly lenacapavir was tested in a trial that included trans women, trans men and non-binary people, and early research suggests no clinically significant interaction with feminising or masculinising hormones. It is not yet approved for general use here; see the current status of lenacapavir in Thailand.
Cabotegravir injections every two months are another option; our page on injectable PrEP in Bangkok explains how they work, and you can ask us whether they are available for you.
Getting PrEP in Bangkok as a trans person
Our English-speaking doctors will use the name and pronouns you give us, and you only share as much medical history as is needed for safe prescribing. You can book by LINE, WhatsApp or phone.
If you are visiting Thailand, bring the names and doses of your hormones, either written down or as photos of the packets. That is usually enough for the doctor to check for interactions.
Before your visit, you might find it useful to read how well PrEP protects you and who PrEP is designed for, or take the one-minute PrEP self-check. When you are ready, book an appointment with our doctors.
Had condomless sex in the last 72 hours without PrEP cover? You need PEP, not PrEP. Ask us about urgent PEP straight away.
Questions people ask
Does PrEP reduce the effect of my hormones?
No. Studies, including iFACT and iFACT-3 in Thailand, found estradiol levels were not lowered by PrEP. No interaction is expected with testosterone either.
Can trans women use 2-1-1 PrEP?
Only trans women who are not taking estradiol-based hormones, do not have hepatitis B, and are using it for anal sex. If you take estradiol, use daily PrEP.
Is PrEP safe for trans men on testosterone?
Yes, PrEP is used safely by trans men on testosterone. Take it daily, and allow about 21 days before relying on it for front-hole sex.
Do I have to stop hormones before an HIV test or starting PrEP?
No. Keep taking your hormones as usual. They do not affect HIV test results or your ability to start PrEP.
Should I tell the doctor which hormones I take?
Yes, including doses and where you get them. It helps with kidney monitoring and any future medicine decisions, and it stays confidential.
Written by the HIV PrEP Bangkok team, based on WHO guidance and the Liverpool HIV drug interactions database. Last updated 2 October 2026.