Medically reviewed by Charles Maddix, MSN, APRN, PMHNP-BC
Last updated: July 2026

PrEP and Testosterone (TRT): What Men on Hormones Should Know

Testosterone therapy and PrEP get prescribed by different clinicians, monitored with different labs, and rarely discussed in the same visit. So the practical questions go unanswered: does testosterone blunt PrEP? Does PrEP mess with your T levels? Which labs overlap, and which one should you be watching? Here's what the evidence actually says — for cisgender men on TRT and for transgender men on testosterone, since the same pharmacology applies to both.

Does testosterone make PrEP less effective?

Not based on anything measured so far. The pharmacology argument is simple: tenofovir and emtricitabine are cleared by the kidneys, not by the liver enzymes that process testosterone, so there's no obvious mechanism for one to crowd out the other. The Liverpool interaction checker — the reference most HIV clinicians use — lists TDF-FTC plus testosterone as green: the combination hasn't been formally studied, but "based on metabolism and clearance a clinically significant interaction is unlikely."

The closest thing to direct evidence is the iBrEATHe study, run by Robert Grant's group and published in 2020. It enrolled 24 HIV-negative transgender men who had been stable on testosterone — injected, topical, or implanted — for at least six months, then had them take daily Truvada for four weeks with near-total observed adherence (over 99% of doses). Tenofovir concentrations in the trans men ran about 23% lower than in cisgender women measured the same way, a statistically significant difference, but they matched the levels seen in cisgender men and were all above the thresholds associated with high protection. The investigators concluded the results support standard TDF-based PrEP dosing. That's one small, short study — not a large outcomes trial — but it points the same direction as the pharmacology.

Does PrEP lower your testosterone?

Same study, same answer: after four weeks on Truvada, testosterone concentrations in the trans men were unchanged. CDC's 2021 PrEP guideline states in its interaction table that TDF does not affect hormone levels (its note is written about feminizing hormones, but the mechanism argument is the same). If your T levels drift after starting PrEP, the far more likely culprits are the usual ones — dose timing, injection interval, absorption of a gel — not the PrEP pill.

Where the evidence is honestly thin

CDC's guideline says plainly that the studies informing it included small numbers of transgender women and none included transgender men, so data specific to people on testosterone are "often limited or not available." Cisgender men on TRT for low testosterone weren't studied as a group either — they were simply mixed into the general male population of the PrEP trials, which is reassuring in a loose way but isn't the same as a dedicated analysis. The iBrEATHe result is a blood-level study, not an HIV-prevention outcome. None of that is a reason to hesitate; it's a reason to expect your clinician to say "no known interaction" rather than "proven no interaction," and to mean the difference.

The labs: where testosterone and PrEP actually overlap

This is the part that matters in practice, because the two therapies pull on the same blood tests in ways that can confuse a clinician who only sees half the picture.

Creatinine and kidney function

TDF-based PrEP (Truvada and its generics) requires kidney checks: CDC guidance sets a floor of an estimated creatinine clearance of 60 mL/min to start, with monitoring every 12 months for most people and every 6 months if you're 50 or older or started with a clearance under 90. Descovy (TAF-based) has a lower floor of 30 mL/min. The catch is that the standard kidney estimate is calculated from serum creatinine, and creatinine rises with muscle mass. Testosterone builds muscle. So a man a year into TRT can show a higher creatinine and a lower calculated clearance than before, without his kidneys having changed at all. Researchers studying transgender people on hormones have looked at cystatin C, a marker that doesn't depend on muscle, as a cleaner alternative in exactly this situation. The takeaway isn't to skip the test — it's that a creatinine bump on TRT plus TDF deserves interpretation, not panic, and sometimes a second marker.

Hematocrit

Testosterone raises red-cell production. The American Urological Association's guideline directs clinicians to measure hemoglobin and hematocrit before starting testosterone and to warn patients about polycythemia, and the Endocrine Society's systematic review found erythrocytosis (hematocrit above 54%) significantly more common on testosterone than placebo. This is a testosterone issue, not a PrEP one — PrEP isn't known to move your blood count — but it's the lab that most often gets a TRT patient's dose changed, and it's easy to bundle with your PrEP draw if the same practice manages both.

Bone density

TDF-FTC produced a small, reversible decrease in bone mineral density in PrEP studies, and CDC does not recommend routine bone scans for people on PrEP. Testosterone therapy, by contrast, is generally expected to support bone density rather than erode it. For most men on both, bone isn't a reason to choose one PrEP option over another; if you have a separate bone-health concern, that's a conversation for the visit and a possible nudge toward Descovy or an injectable.

What about the injectables?

Cabotegravir (Apretude) sidesteps the kidney question entirely — CDC guidance says no kidney assessment is needed for it — which makes it an appealing fit for someone whose creatinine is already muddied by testosterone. No interaction between cabotegravir and testosterone is flagged in CDC guidance, though like the pills it hasn't been studied head-to-head with TRT.

Lenacapavir (Yeztugo), which CDC added as a strongly recommended twice-yearly PrEP option in September 2025, deserves one honest asterisk. Its prescribing information describes it as a moderate inhibitor of the liver enzyme CYP3A, and warns that it can raise levels of drugs that are sensitive CYP3A substrates — an effect that can persist for up to nine months after the last injection. Testosterone is partly metabolized by CYP3A, but it isn't listed as a sensitive substrate and the label says nothing about testosterone or hormones. So: no interaction is flagged, but "not flagged" is not "studied." Worth noting that 22% of PURPOSE 2 trial participants identified as gender-diverse, so some people on hormones were in the trial; the label just doesn't break out their results. If you're on lenacapavir and your T levels or side effects shift, tell both prescribers.

A note for men who get testosterone outside a clinic

Some men source testosterone from gyms, online sellers, or a friend. Two things matter here. First, tell your PrEP prescriber anyway — the lab-interpretation issues above apply whether or not the T is prescribed, and a clinician who doesn't know about it may read a rising creatinine or hematocrit as a PrEP problem. Second, CDC's guideline specifically notes that non-sterile injection of non-prescribed hormones is its own HIV risk, separate from sex. PrEP covers the sexual exposure; it doesn't make shared needles safe.

When to talk to a clinician

Starting either therapy while on the other is routine, but it goes better with one person who sees the whole picture. Raise it if your creatinine or calculated kidney function drops after starting TRT while on Truvada; if your hematocrit is climbing; if you're on lenacapavir and anything about your testosterone response changes; or if you're a trans man on testosterone who's been told PrEP "might not work as well" — the best available evidence says otherwise, and you deserve the actual data rather than a hedge. Our reviewing clinical team prescribes PrEP by telehealth and can coordinate with whoever manages your testosterone, or manage both — the $25/month membership covers the visits and lab coordination, and you can book a visit directly.

The bottom line

Testosterone and PrEP don't fight each other. The pills and testosterone have no known interaction; the one study that checked found protective PrEP levels and stable testosterone; and the injectables are, if anything, simpler. What changes is how your labs should be read. Make sure whoever orders your PrEP labs knows you're on testosterone, and whoever manages your testosterone knows which PrEP option you're on.