References UK clinical guidance from the NHS, the British HIV Association (BHIVA), and the British Association for Sexual Health and HIV (BASHH). Last updated: April 2026.
Darunavir (brand name Prezista) is a protease inhibitor (PI) used to treat HIV. It’s one of the most potent PIs available and has a high barrier to resistance, making it a reliable option for people who need a protease inhibitor in their regimen. Darunavir is always taken with a pharmacokinetic booster — either ritonavir or cobicistat — to keep drug levels effective.
Here’s what darunavir does, when it’s used, and what to expect.
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HIV uses an enzyme called protease to cut long protein chains into functional pieces during replication. Darunavir blocks this enzyme, preventing the virus from assembling new copies of itself. Without protease, HIV produces defective, non-infectious viral particles.
- As part of combination ART when a protease inhibitor is preferred
- For people with resistance to other drug classes
- When drug interactions rule out integrase inhibitors
- As part of the fixed-dose combination Symtuza (darunavir + cobicistat + emtricitabine + TAF)
- In pregnancy — darunavir is widely used and well-studied
| Formulation | Dose | With Food? |
|---|---|---|
| Darunavir 800mg + ritonavir 100mg once daily | Treatment-experienced without resistance | Yes |
| Darunavir 600mg + ritonavir 100mg twice daily | Treatment-experienced with some resistance | Yes |
| Symtuza (single tablet) | Once daily | Yes |
Food increases absorption significantly — always take darunavir with a meal.
Side Effects
- Diarrhoea (most common)
- Nausea
- Headache
- Rash (usually mild; rarely serious — stop and seek advice if widespread)
- Raised cholesterol and triglycerides
- Possible effects on blood sugar in some people
Drug Interactions
Because darunavir is boosted with ritonavir or cobicistat, it has many drug interactions. Key ones include:
- Statins — some are contraindicated; pravastatin or rosuvastatin preferred
- Rifampicin — contraindicated
- Some contraceptives — may need adjustment
- Sildenafil, tadalafil — dose must be reduced
- Anticonvulsants — some lower darunavir levels
Always tell your HIV team and pharmacist about every medicine you take.
Read more: What is HIV? | Symtuza | Ritonavir
Frequently Asked Questions
Ritonavir or cobicistat slows the liver enzymes that break down darunavir, keeping its levels high enough to be effective. Without a booster, drug levels would drop too quickly.
Yes, if you have no significant protease inhibitor resistance. If resistance is present, twice-daily dosing may be needed.
Yes. Darunavir with ritonavir is widely used in pregnancy and has a good safety track record for both mother and baby.
Related reading
- Choosing the Right PrEP Drug: Truvada vs Descovy
- Dovato for HIV: A Two-Drug Regimen
- Triumeq for HIV: A Straightforward Guide
- Efavirenz for HIV: An Older NNRTI Still in Use
- Eviplera: How This Anti-HIV Drug Works
Sources
- NHS — Sexual health conditions
- BASHH — UK clinical guidelines for STI management
- British HIV Association (BHIVA) — HIV treatment guidelines
- Terrence Higgins Trust — sexual health information
- UK Health Security Agency — STI surveillance data
Steve Page is a recognised expert on Sexually Transmitted Diseases (STDs) and STD treatments, having published numerous articles in peer-reviewed journals and presented his research at conferences around the world. He has an in-depth understanding of the latest medical research on STDs, and is an advocate for the development of new treatments and protocols to improve the health of those affected. In addition to his research, he has dedicated his career to understanding the causes and symptoms of STDs, as well as how to best treat those impacted.
