Last updated: July 2026
PrEP Side Effects: The Honest Guide
Fear of side effects is one of the top reasons people delay starting PrEP — and it's largely based on outdated impressions from early HIV treatment drugs. Modern PrEP is among the better-tolerated daily medications in medicine. Here's what actually happens, by option.
The short version
- Most people on PrEP feel no different at all.
- "Start-up syndrome" (mild nausea/headache, first 2–4 weeks) affects roughly 1 in 10 and resolves on its own.
- The monitored risks — kidney (TDF) and bone — are small, tracked with routine labs, and generally reversible.
- Quarterly follow-up is the safety system: it catches problems long before they matter.
Truvada / generic TDF-FTC
Start-up nausea, headache, or fatigue in the first weeks affects a minority and nearly always resolves. The two monitored effects: a small average decrease in kidney filtration (reversible on stopping; why creatinine is checked at baseline and periodically — clinically significant kidney injury on PrEP is uncommon and concentrated in people with preexisting risk) and small decreases in bone mineral density (~1%, largely recovering after stopping; relevant if you have osteoporosis risk). Full Truvada guide.
Descovy / TAF-FTC
Designed to minimize exactly those two effects — kidney and bone impacts are measurably smaller. The trade-offs seen in trials: modest weight gain and lipid increases relative to TDF (which mildly suppresses both). For most healthy people these differences are clinically minor in both directions. Full Descovy guide.
Apretude (injectable)
Injection-site reactions — soreness, a small lump, occasionally a day of feeling off — affect most people at least once and fade within days; they diminish with subsequent shots. Systemic side effects are uncommon. The unique consideration is the pharmacologic "tail": levels decline slowly over many months after stopping, so discontinuing requires a plan with your clinician. Full Apretude guide.
What PrEP does not do
Decades of surveillance have found no effect on hormones or sexual function, no interaction with alcohol or recreational cannabis, no interference with gender-affirming hormone therapy (a specifically studied question — levels of both remain effective), and no fertility impact. The persistent myths on these points keep people off a 99%-effective prevention tool.
When to call your prescriber
Persistent vomiting or inability to keep doses down; new significant swelling, urination changes, or flank pain (kidney); yellowing skin/eyes; or any symptom that worries you between visits — that's what the message portal is for. And if you ever stop PrEP, tell your clinician rather than just stopping: how you stop safely depends on which option you're on. Ready to talk it through? Start here.