Darunavir: What it does and how to use it safely

Darunavir is a protease inhibitor used to treat HIV. It blocks a viral enzyme so HIV can't make new infectious particles. Doctors usually give it as part of a combination antiretroviral regimen — never alone. You probably care less about mechanism and more about how to take it, what can go wrong, and what to watch for. Here’s a clear, practical guide.

Common dosing and boosters

Darunavir needs a booster to work well. For most adults the usual dose is darunavir 800 mg once daily plus ritonavir 100 mg once daily or darunavir 800 mg once daily with cobicistat 150 mg once daily. If someone has certain resistance mutations or past treatment failure, doctors may use 600 mg twice daily with ritonavir 100 mg twice daily. Always follow your clinician’s prescription — dosing can change with other drugs, kidney or liver issues, and resistance patterns.

Take darunavir with food. Food increases absorption and helps steady levels in your blood. Missing doses reduces effectiveness and raises the chance of resistance. If you forget one dose, take it as soon as you remember unless it’s almost time for the next dose — then skip the missed dose and continue the schedule. Don’t double up without checking your provider.

Side effects, monitoring and safety

Common side effects include nausea, diarrhea, headache, and rash. Darunavir can also raise cholesterol, triglycerides, and blood sugar in some people. Liver enzyme increases happen, especially if you have hepatitis B or C. Tell your doctor about any persistent stomach problems, skin rash, yellowing of the skin, or new muscle pain.

Before and during treatment you’ll likely get tests for viral load and CD4 count, plus blood tests for liver function, lipids, and glucose. If viral load doesn’t drop as expected, resistance testing is usually done to guide changes.

Drug interactions are a big deal with darunavir because it affects and is affected by the CYP3A4 enzyme. Some medicines you should avoid or use with caution include simvastatin and lovastatin (use atorvastatin or pravastatin instead under supervision), certain benzodiazepines, rifamycins, St John’s wort, and some anti-arrhythmics. Always give your HIV team a full list of your meds, supplements, and herbal products.

If you have a sulfa allergy, mention it — darunavir is related to sulfonamides and your doctor will weigh risks and benefits. Pregnant people should discuss risks and alternatives; many antiretrovirals are used safely in pregnancy but choices depend on the whole regimen.

Finally: darunavir is prescription-only. Don’t try to source it without a valid prescription. Use licensed pharmacies and keep in regular contact with your clinic. Sticking to the regimen, attending monitoring visits, and being upfront about side effects will get the best results from darunavir.