Cobicistat
Cobicistat is a “booster” medicine that raises blood levels of the HIV drugs atazanavir or darunavir, so they work better as part of HIV-1 treatment.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Cobicistat (Tybost) is a booster with no HIV activity of its own; it blocks CYP3A, a liver enzyme, so atazanavir or darunavir stay at higher levels in HIV-1 treatment, and since about 2012 it has been the main alternative to ritonavir. It is usually well tolerated, with nausea, diarrhea or headache the common complaints, plus yellowing of the eyes or skin, mostly with atazanavir. Watch for drug interactions, which can push other medicines to harmful levels or weaken your HIV treatment and invite resistance. Expect kidney checks, since it nudges up creatinine (a kidney blood test) without real harm, though kidney injury has occurred with tenofovir disoproxil regimens.
Clinical pearls
- Take it with food at the same time as your atazanavir or darunavir; with atazanavir, space antacids at least two hours apart.
- Never take it with ritonavir or another cobicistat-containing combination tablet, a mix-up that is easy to make when regimens change.
- St. John’s wort, rifampin, carbamazepine, phenytoin and simvastatin are off limits, so check every new medicine with your pharmacist first.
- Pregnancy changes the plan, since boosted atazanavir or darunavir levels fall in later trimesters and this combination is not recommended.
Patient information guide A plain-language walkthrough of Cobicistat, written from its FDA label.
What Cobicistat is used for
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Cobicistat is a booster used in HIV-1 treatment.
- Tybost raises exposure to atazanavir or darunavir (once-daily regimens) in adults with HIV-1 infection.
- Tybost is also used in children with HIV-1 weighing at least 14 kg.
- It is always combined with other HIV medicines.
How Cobicistat works
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Cobicistat is a mechanism-based inhibitor of CYP3A, an enzyme that breaks down certain medicines. By blocking it, cobicistat raises the levels of atazanavir and darunavir in the body.
Studies found that atazanavir or darunavir levels with cobicistat were comparable to levels with ritonavir, another booster. It is not interchangeable with ritonavir for every HIV drug.
Cobicistat dosage
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Tybost is a once-daily medicine taken by mouth. Take it at the same time as atazanavir or darunavir, with food. Dosing in children depends on body weight. Follow your prescriber and the label, and ask your pharmacist what to do about a missed dose.
Dosing details from the FDA-approved label
From the Cobicistat prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Adults, treatment-naïve or treatment-experienced, coadministered with atazanavir
- TYBOST 150 mg orally once daily with atazanavir 300 mg orally once daily, given with food at the same time
- Assess estimated creatinine clearance before starting; not recommended during pregnancy
- Adults, treatment-naïve or treatment-experienced with no darunavir resistance-associated substitutions, coadministered with darunavir
- TYBOST 150 mg orally once daily with darunavir 800 mg orally once daily, given with food at the same time
- Not recommended during pregnancy
- Pediatric patients with atazanavir, weighing at least 14 kg to less than 25 kg
- TYBOST 90 mg orally once daily with atazanavir 200 mg orally once daily
- Dosed by body weight, given with food
- Pediatric patients with atazanavir, weighing at least 25 kg to less than 35 kg
- TYBOST 150 mg orally once daily with atazanavir 200 mg orally once daily
- Dosed by body weight, given with food
- Pediatric patients with atazanavir, weighing at least 35 kg
- Atazanavir 300 mg orally once daily (TYBOST dose not stated in the table text)
- Dosed by body weight, given with food
- Pediatric patients with no darunavir resistance-associated substitutions, weighing at least 15 kg to less than 25 kg
- TYBOST 90 mg orally once daily with darunavir 600 mg orally once daily
- Dosed by body weight, given with food
- Pediatric patients with darunavir, weighing at least 25 kg to less than 30 kg
- TYBOST 150 mg orally once daily with darunavir 600 mg orally once daily
- Dosed by body weight, given with food
- Pediatric patients with darunavir, weighing at least 30 kg to less than 40 kg
- Darunavir 675 mg orally once daily (TYBOST dose not stated in the table text)
- Dosed by body weight, given with food
- Pediatric patients with darunavir, weighing at least 40 kg
- Darunavir 800 mg orally once daily (TYBOST dose not stated in the table text)
- Dosed by body weight, given with food
- Patients with renal impairment coadministered with TDF
- Not recommended with estimated creatinine clearance below 70 mL/min
- Dose adjustment of TDF is required below 50 mL/min and has not been established with TYBOST
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION TYBOST must be coadministered with atazanavir or darunavir at the same time, with food, and in combination with other HIV-1 antiretroviral agents. ( 2.1 , 2.2 ) Recommended dosage in adults: ( 2.1 ) Adult Patient Populations Coadministered Agent Dosage TYBOST Dosage Treatment-naïve or treatment-experienced atazanavir 300 mg orally once daily 150 mg orally once daily Treatment-naïve or treatment-experienced with no darunavir resistance-associated substitutions darunavir 800 mg orally once daily Recommended dosage in pediatric patients: TYBOST 150 mg or TYBOST 90 mg orally once daily based on body weight. For dosage recommendations for TYBOST and the coadministered protease inhibitor atazanavir or darunavir in pediatric patients, refer to Table 2 and Table 3 of the full prescribing information respectively. ( 2.2 ) Prior to starting TYBOST, assess estimated creatinine clearance. ( 2.3 ) Coadministration with tenofovir disoproxil fumarate (TDF): assess estimated creatinine clearance, urine glucose, and urine protein at baseline. ( 2.3 ) TYBOST coadministered with TDF is not recommended in patients who have an estimated creatinine clearance below 70 mL/min because dose adjustment of TDF is required below 50 mL/min and such dose adjustments have not been established for coadministration with TYBOST. ( 2.4 ) 2.1 Recommended Dosage in Adults Administer TYBOST in conjunction with atazanavir or darunavir and other antiretroviral agents in the treatment of adults with HIV-1 infection. The recommended dosages of TYBOST and atazanavir or darunavir given with food are presented in Table 1 . TYBOST must be coadministered at the same time as atazanavir or darunavir [see Drug Interactions (7) ]. Consult the prescribing information for atazanavir or darunavir. Table 1 Recommended Dosing Regimens in Treatment-Naïve or Treatment-Experienced Adults Patient Populations Coadministered Agent Dosage TYBOST Dosage Treatment-naïve or treatment-experienced atazanavir 300 mg orally once daily 150 mg orally once daily Treatment-naïve or treatment-experienced with no darunavir resistance-associated substitutions darunavir 800 mg orally once daily 2.2 Recommended Dosage in Pediatric Patients Administer TYBOST in conjunction with atazanavir or darunavir and other antiretroviral agents in the treatment of pediatric patients with HIV-1 infection.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Cobicistat side effects
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In studies with atazanavir, the most common side effects were:
Common side effects
- Jaundice (yellowing of the skin)
- Yellowing of the whites of the eyes (ocular icterus)
- Rash
- Nausea
- Diarrhea
- Headache
When to get medical help
- Call your doctor if you have kidney problems such as new or worsening kidney trouble. This has been reported when Tybost is used with a tenofovir disoproxil fumarate (TDF) regimen.
- Get medical help for signs of a serious allergic-type skin reaction or a spreading rash.
- Tell your doctor right away about muscle pain or breakdown (rhabdomyolysis), which was reported less commonly.
- Call your doctor if you notice yellowing of the skin or eyes that is new or worsening.
- Contact your doctor if your HIV medicines seem to stop working. Some drug interactions can reduce their effect and lead to resistance.
Cobicistat warnings and precautions
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- Kidney effects: cobicistat raises creatinine and lowers estimated kidney function without changing true filtering. Kidney function should be checked before and during treatment.
- With TDF, acute kidney failure and Fanconi syndrome have been reported. Urine glucose and protein should be monitored.
- Drug interactions can be serious or life-threatening, or cause HIV treatment to fail.
- Not recommended with ritonavir or with more than one boosted HIV drug.
- Not recommended during pregnancy.
Cobicistat interactions
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Cobicistat blocks CYP3A and CYP2D6 and several transporters, so it can raise levels of many drugs.
- St. John’s wort, rifampin, carbamazepine, phenobarbital, and phenytoin: contraindicated, since they can cause loss of effect.
- Simvastatin, lovastatin, and lomitapide: contraindicated because of higher levels.
- Colchicine, ranolazine, alfuzosin, and dronedarone: contraindicated because of serious risks.
- Rivaroxaban: not recommended because of bleeding risk.
- Digoxin and other heart rhythm drugs: dose changes or monitoring.
- Antacids with atazanavir: separate by at least 2 hours.
Interactions listed in the FDA-approved label
From the Cobicistat prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Drugs highly dependent on CYP3A for clearance (serious and/or life-threatening events with elevated levels): Cobicistat inhibits CYP3A and CYP2D6, which may increase plasma concentrations of these drugs. Coadministration is contraindicated.
- CYP3A inducers: May decrease plasma concentrations of cobicistat, atazanavir and darunavir, which may lead to loss of therapeutic effect and development of resistance. Consult Table 7 and the full prescribing information.
- Fosamprenavir, saquinavir, tipranavir: Pharmacokinetic data are not available to provide dosing recommendations. Coadministration is not recommended.
- Lopinavir, ritonavir-containing regimens, other cobicistat-containing products: Lopinavir is co-formulated with ritonavir; more than one agent requiring pharmacokinetic enhancement is not recommended. Use with TYBOST is not recommended.
- Efavirenz: Decreases cobicistat, darunavir and atazanavir levels. With darunavir: not recommended. With atazanavir in treatment-naïve adults: atazanavir 400 mg with TYBOST 150 mg once daily with food, efavirenz 600 mg once daily on an empty stomach, preferably at bedtime. Not recommended in treatment-experienced patients.
- Nevirapine: Decreases atazanavir and cobicistat, increases nevirapine; may cause loss of therapeutic effect and resistance. Contraindicated with atazanavir; not recommended with darunavir.
- Etravirine: Decreases cobicistat and atazanavir; may result in loss of therapeutic effect and resistance. Coadministration is not recommended.
- Maraviroc: Increases maraviroc levels. Adult patients should receive maraviroc 150 mg twice daily.
- Alfuzosin, ranolazine, dronedarone: Increased levels with potential for serious and/or life-threatening reactions. Coadministration is contraindicated.
- Antacids (e.g., aluminum and magnesium hydroxide): Decreases atazanavir levels. With atazanavir, administer a minimum of 2 hours apart.
Read the label’s full interactions text
7 DRUG INTERACTIONS TYBOST, in combination with atazanavir or darunavir, can alter the concentration of drugs metabolized by CYP3A or CYP2D6. Drugs that induce CYP3A can alter the concentrations of TYBOST, atazanavir and darunavir. Consult the full prescribing information prior to and during treatment for potential drug interactions. ( 4 , 5.3 , 7 , 12.3 ) 7.1 Potential Effect of Cobicistat (Coadministered with Atazanavir or Darunavir) on the Pharmacokinetics of Concomitant Drugs Cobicistat is an inhibitor of CYP3A and CYP2D6. The transporters that cobicistat inhibits include p-glycoprotein (P-gp), BCRP, OATP1B1, and OATP1B3. The plasma concentration of drugs that are primarily metabolized by CYP3A or CYP2D6, or are substrates of P-gp, BCRP, OATP1B1, or OATP1B3 may be increased if those drugs are coadministered with TYBOST. Based on in vitro data, cobicistat is not expected to induce CYP1A2 or CYP2B6 and based on in vivo data, cobicistat is not expected to induce MDR1 or, in general, CYP3A to a clinically significant extent. The induction effect of cobicistat on CYP2C9, CYP2C19, or UGT1A1 is unknown, but is expected to be low based on CYP3A in vitro induction data. Coadministration of TYBOST with atazanavir or darunavir with drugs highly dependent on CYP3A for clearance and for which elevated plasma concentrations are associated with serious and/or life-threatening events is contraindicated. Coadministration with drugs that have active metabolite(s) formed by CYP3A may result in reduced plasma concentrations of these active metabolite(s). Coadministration with other CYP3A substrates may require a dose adjustment or additional monitoring as shown in Table 7 . 7.2 Potential Effect of Concomitant Drugs on the Pharmacokinetics of Cobicistat (Coadministered with Atazanavir or Darunavir) Cobicistat is metabolized by CYP3A, and to a minor extent, by CYP2D6. Atazanavir and darunavir are also metabolized by CYP3A.
Excerpted — the section continues on the label. Read the full Drug Interactions section on DailyMed →
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Cobicistat
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- Kidney disease or low creatinine clearance, especially if TDF is part of your regimen.
- Pregnancy: not recommended with darunavir or atazanavir, and should not be started during pregnancy.
- Children weighing less than 14 kg should not use it.
- Share a full list of your medicines and supplements.
Cobicistat overdose
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If too much is taken, the person should be watched for signs of toxicity and given supportive care, such as monitoring vital signs. Dialysis is unlikely to remove cobicistat because it is highly protein-bound.
What Cobicistat does in the body
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Cobicistat raised atazanavir and darunavir levels to be comparable to ritonavir boosting in studies. It lengthened the PR interval (an ECG measure) but did not affect the QT interval. It also raises serum creatinine by blocking its release into urine, without changing true kidney filtering.
How your body processes Cobicistat
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Cobicistat peaks about 3.5 hours after a dose when taken with food. It is mostly bound to proteins in the blood and is broken down mainly by CYP3A. Its half-life is about 3 to 4 hours. Most of it leaves in the feces, with a smaller amount in the urine.
How to store Cobicistat
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Store at 25 °C (77 °F); excursions permitted to 15°C –30 °C (59–86 °F) (see USP Controlled Room Temperature).
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Cobicistat
30 supplements and herbal products have documented interactions with Cobicistat in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 1
- Moderate · 19
- Minor · 10
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
Cobicistat: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Cobicistat — the kind of thing our pharmacy team would talk through with you at the counter.
What is cobicistat actually for?
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How should I take it?
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What side effects should I expect?
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Why does my kidney test change?
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Can I take other medicines or supplements with it?
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Is it safe in pregnancy?
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Is Cobicistat available over the counter?
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When was Cobicistat first available?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Cobicistat on HelloPharmacist
Cobicistat forms and strengths (how it comes)
Cobicistat is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Cobicistat inactive ingredients by manufacturer.
Tablet
How this form is used
- Tybost is used to boost atazanavir or darunavir (once daily) in HIV-1 treatment with other antiretrovirals.
- Tybost is approved for adults and children weighing at least 14 kg.
- Tybost is taken by mouth once daily.
- Tybost must be taken at the same time as atazanavir or darunavir, with food.
- Tybost is used together with other HIV-1 medicines.
Cobicistat on the U.S. market: products, makers and brands
How Cobicistat appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
1 company lists 1 Cobicistat product record with the FDA, mostly as tablet; the earliest marketing or approval year on record is 2012. Brand names on the directory include Tybost; the rest are generics.
Also listed with the FDA, not a patient dose form: Powder (6) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
How widely Cobicistat is used (Medicaid data)
A general measure of how commonly Cobicistat is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Cobicistat is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Cobicistat prescribed? Of the 1,601 medications we measure, Cobicistat ranks #1,549 by Medicaid prescriptions — more than 3% of them.
Utilization by Cobicistat product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
cobicistat 150 MG Oral Tablet
Summed across the 1 of 2 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1551993
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Cobicistat, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 1 of 2 listed Cobicistat NDCs with Medicaid activity.
Compare Cobicistat products
A representative set of FDA-listed product records for Cobicistat — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Tablet | ||||
| 150 mg | Oral | Gilead Sciences, Inc. | NDA | View NDC → |
Showing 1 of 1 products — FDA National Drug Code Directory. See every product, package size and price: browse all 1 Cobicistat NDCs →
Cobicistat side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Cobicistat — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Cobicistat in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Cobicistat FDA approval history
How Cobicistat went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Cobicistat recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no Cobicistat recalls since July 2021.
✅No Cobicistat recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 1306284 1 dose form · 1 strength
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Dose form (SCDF) Oral Tablet RxCUI 1551992In current FDA listingsClinical drug / strength (SCD) 150 MGRxCUI 1551993
Look up RxCUI 1306284 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Cobicistat supply and shortage status
Whether Cobicistat is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
Cobicistat brand names
Cobicistat is sold under one brand name in the FDA directory — Tybost. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Cobicistat: manufacturers and labelers
One company lists Cobicistat products with the FDA. By number of product records, the largest are Gilead Sciences, Inc.. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Cobicistat drug class (RxNorm)
Cobicistat belongs to the Cytochrome P450 3A Inhibitor class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Cobicistat page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Gilead Sciences, Inc. is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →