Cobicistat
Cobicistat is a pharmacokinetic booster used alongside HIV-1 antiretroviral medicines to help them reach effective levels in the blood.
🧬 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: Patient Information Guide
A plain-language walkthrough of Cobicistat — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Cobicistat (Tybost) is a pharmacokinetic booster — it raises and maintains the blood levels of certain HIV medicines so they can work effectively.
- Tybost is indicated to boost atazanavir or darunavir (once-daily dosing) as part of a combination HIV-1 regimen in adults
- Tybost is also indicated for pediatric patients weighing at least 14 kg (about 31 lbs), used to boost atazanavir or darunavir (once-daily) alongside other HIV medicines
- Tybost is not recommended with darunavir twice-daily, fosamprenavir, saquinavir, or tipranavir — it has not been shown to work safely with these agents
- Tybost is not interchangeable with ritonavir for all purposes — drug interactions may differ even when both are used with atazanavir or darunavir
⚙️How it works▾
Cobicistat works by blocking a key liver enzyme called CYP3A — part of the body's system for breaking down and clearing drugs. When CYP3A is inhibited, atazanavir and darunavir are cleared from the body more slowly, keeping their blood levels higher and more consistent. This is called pharmacokinetic boosting, and it allows those HIV medicines to remain effective without needing higher doses on their own.
Cobicistat also inhibits other drug transporters (including P-gp, BCRP, OATP1B1, and OATP1B3), which is why it interacts with so many other medications. It does not itself fight HIV — its entire role is to improve how long your HIV medicine stays active in your system.
💊How it's taken▾
Tybost tablets are taken orally once daily, always at the same time as atazanavir or darunavir, and always with food. The dose in pediatric patients is determined by the child's body weight. Never take Tybost without the HIV medicine it is meant to boost.
- Always take with food — this applies whether you are taking it with atazanavir or darunavir
- Take all medicines in your regimen at the same time each day
- If you miss a dose, follow your prescriber's guidance — do not double up without asking
🤒Side effects — in detail▾
The most common side effects seen with Tybost (when used with atazanavir) include:
- Jaundice — yellowing of the skin or eyes (fairly common; often related to atazanavir's effect on bilirubin)
- Rash (including allergic skin reactions)
- Ocular icterus — yellowing of the whites of the eyes
- Nausea
- Diarrhea
- Headache
- Fatigue
- Sleep disturbances, abnormal dreams, or depression
More serious reactions that need prompt medical attention include signs of kidney problems (decreased urination, swelling, bone pain), severe muscle pain (possible rhabdomyolysis), or kidney lab abnormalities such as glycosuria or hematuria — your doctor will monitor for these with regular lab tests.
⚠️Warnings & precautions▾
- Kidney test changes: Tybost reliably raises serum creatinine by blocking how the kidneys secrete it — this does not mean your kidneys are damaged, but it can make test results hard to interpret. Your doctor will check kidney function before and during treatment.
- Real kidney damage risk with TDF: When Tybost is combined with tenofovir disoproxil fumarate (TDF), there is a genuine risk of kidney damage, including Fanconi syndrome (a disorder affecting the kidney's ability to reabsorb nutrients). This combination is not recommended if your estimated kidney clearance is below a certain level. Regular urine and blood monitoring is required.
- Drug interactions: Cobicistat interacts with a very large number of medicines. Some combinations can cause life-threatening reactions or make your HIV medicines stop working. Your full medication list must be reviewed every time something changes.
- Pregnancy: Tybost with atazanavir or darunavir is not recommended during pregnancy — drug levels drop significantly in the second and third trimesters, which could allow the virus to rebound.
- Not all boosting combinations are safe: Using Tybost with more than one agent that needs pharmacokinetic boosting, or adding ritonavir, is not recommended.
🔀What it interacts with▾
Cobicistat is a potent inhibitor of drug-processing enzymes and transporters, which means it affects the levels of many other medicines in your body. Key interactions include:
- Contraindicated drugs (never combine): alfuzosin (prostate), ranolazine (heart), dronedarone (heart rhythm), carbamazepine/phenobarbital/phenytoin (seizures), rifampin (antibiotic), colchicine (gout), St. John's wort (herbal), lovastatin/simvastatin (cholesterol), lurasidone/pimozide (psychiatric), ergot derivatives, triazolam and oral midazolam (sedatives), and sildenafil as Revatio (pulmonary arterial hypertension) — some contraindications apply only when Tybost is used with atazanavir specifically
- Blood thinners (DOACs): Apixaban and rivaroxaban levels increase, raising bleeding risk — dose adjustments or avoidance may be needed
- Other HIV medicines: Combining with ritonavir, lopinavir/ritonavir, or other fixed-dose cobicistat products is not recommended; several antiretroviral combinations are also not recommended due to loss of effectiveness
- Antibiotics: Clarithromycin, erythromycin, and telithromycin levels may rise — consider alternatives
- Heart medicines: Digoxin levels increase; amiodarone, flecainide, and other antiarrhythmics need clinical monitoring
- Cancer medicines: Irinotecan is contraindicated with atazanavir; vincristine, vinblastine, dasatinib, and nilotinib may need dose adjustments
- Antacids: When using Tybost with atazanavir, take antacids at least 2 hours apart
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- Tell your doctor if you have kidney disease or low kidney function — Tybost affects kidney tests and can worsen kidney problems in certain combinations
- Pregnancy: Tybost with atazanavir or darunavir is not recommended during pregnancy; do not start this combination if you are pregnant, and switch to an alternative if you become pregnant while taking it
- Register with the Antiretroviral Pregnancy Registry (1-800-258-4263) if you are or become pregnant while taking Tybost
- Children: Not recommended for patients weighing less than 14 kg (about 31 lbs); dosing in children is based on body weight
- Provide a complete list of all medications, supplements, and herbal products to your doctor and pharmacist before starting — the interaction list is extensive
- Your doctor must check your estimated creatinine clearance before starting; if you are also taking TDF, urine glucose and urine protein should also be checked at baseline
- If you have chronic kidney disease and are taking TDF with Tybost, your serum phosphorus should also be monitored
🚑If you take too much▾
If too much Tybost is taken, seek medical attention and monitor for signs of toxicity. Treatment is supportive — that means watching vital signs and your overall clinical status carefully. Because cobicistat binds very tightly to proteins in the blood, dialysis is unlikely to remove a meaningful amount of it from the body.
📡Pharmacodynamics — effects in the body▾
Cobicistat raises the blood levels of atazanavir and darunavir by slowing the enzyme that would otherwise break them down, resulting in drug exposures that are comparable to those achieved with ritonavir boosting. It also causes a predictable, modest increase in serum creatinine — not by damaging the kidneys, but by blocking the kidneys' normal secretion of creatinine into the urine, which makes the lab value look higher without changing actual kidney filtration. At higher doses than used clinically, cobicistat has also been observed to prolong the PR interval (a measure of electrical conduction in the heart), though standard doses did not affect the QT interval in studies.
🔬Pharmacokinetics — how your body processes it▾
When taken with food, cobicistat reaches peak blood levels roughly 3.5 hours after a dose. It is very highly protein-bound (97–98%), which means very little of it circulates freely in the blood. Cobicistat is broken down mainly by the CYP3A enzyme (and to a small extent by CYP2D6) and has a relatively short half-life of about 3 to 4 hours. Most of the drug leaves the body through the feces (about 86%), with a small amount excreted in urine (about 8%).
📦How to store it▾
Store at 25 °C (77 °F); excursions permitted to 15°C –30 °C (59–86 °F) (see USP Controlled Room Temperature).
📄 Written from Cobicistat’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. 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.
🩺 Pharmacist Counseling Corner
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 exactly does Tybost do — is it treating my HIV? ▾
Do I have to take Tybost with food every time? ▾
My blood creatinine went up since I started Tybost — should I be worried? ▾
Are there medicines I absolutely cannot take with Tybost? ▾
Can I take Tybost if I'm pregnant? ▾
Can my child take Tybost? ▾
Is Cobicistat available over the counter? ▾
When was Cobicistat first available? ▾
Who makes Cobicistat? ▾
💬 Answers drafted from Cobicistat’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
💊 How Cobicistat 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.
Tablet
How this form is used
- Tybost tablets are used to boost atazanavir or darunavir (once-daily) as part of an HIV-1 treatment regimen in adults
- Tybost tablets are used to boost atazanavir or darunavir (once-daily) in pediatric patients weighing at least 14 kg
- Tybost tablets must be taken by mouth once daily, at the same time as atazanavir or darunavir
- Tybost tablets should always be taken with food
- Tybost tablets must be used with other antiretroviral medicines — never as the only HIV drug
- Tybost tablets are not recommended during pregnancy when taken with atazanavir or darunavir
📊 Cobicistat across the U.S. market
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.
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.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
📈 How widely Cobicistat is used
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 1,596 medications we measure, Cobicistat ranks #1,548 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. × 2 listings | NDA | View NDC → |
| 150 mg | — | Patheon Inc. | DRUG FOR FURTHER PROCESSING | View NDC → |
| 💊Bulk drug substance | ||||
| 1 kg/kg | — | Esteve Quimica, SA | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Honour Lab Limited | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Matrix Pharmacorp Private Limited × 2 listings | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | MSN Life Sciences Private Limited | BULK INGREDIENT | View NDC → |
| 35 kg/35 kg | — | Yuhan Chemical | BULK INGREDIENT | View NDC → |
Showing 9 of 9 products — FDA National Drug Code Directory. See every product, package size and price: browse all 9 Cobicistat NDCs →
📈 What people report — real-world data (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.
🏛️ The road to your pharmacy
How Cobicistat went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 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.
Source: openFDA drug enforcement (recall) reports.
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
-
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.
📦 Supply & 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.
🏷️ Sold under these brand names
🏭 Manufacturers & labelers
RxNorm drug class
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.
🔬 Where this comes from
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 we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 1 FDA-filed SPL label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Gilead Sciences, Inc. is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.