Cobicistat side effects: what 618 FDA adverse event reports show

Cobicistat · Tybost · 26 reaction terms · 504 drug–reaction co-reports · data 2026-09-14

Drug class

Cytochrome P450 3A Inhibitor

FDA label (Established Pharmacologic Class) · compare the class

Brand names

Tybost

openFDA label

Who reports

618 reports · 94% serious · 64 with death outcome · 30% female

openFDA FAERS counts, all years, deduplication not applied

Used for

TYBOST is a CYP3A inhibitor indicated to increase systemic exposure of atazanavir or darunavir (once daily dosing regimen) in combination with other antiretroviral agents in the treatment of HIV-1 infection in adults and in pediatric patients weighing at least 14 kg.

FDA label, Indications and Usage

What it is

TYBOST (cobicistat) is a mechanism-based CYP3A inhibitor.

FDA label, Description section

Boxed warning

None in the current label

How to read this page. FAERS is a spontaneous-reporting system: counts are not incidence rates and a signal is not proof of causation. Each reaction below is run through an automated screen — is the term in the FDA label (known), in the indications (the disease being treated), an administrative/coding term, or none of these (unlabeled)? That screen is mechanical text matching, not a causality assessment. The 30 hand-written Bradford Hill assessments are on the causality assessment page. Not medical advice.

Causality screen of the 22 strongest signals

Labeled adverse reaction 1Reporting / coding artifact 6Lab value / disease marker 1Not in label — unassessed 14

What the badges mean

Labeled adverse reaction The exact term appears in the label's warnings or adverse-reactions sections: a known, expected effect. The FAERS signal confirms the label rather than discovering anything.
Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
Lab value / disease marker A laboratory result, investigation or disease-activity marker (antibody positive, CRP abnormal, swollen joint count) not described in the label. These usually mirror the monitored disease or testing protocol rather than a drug effect; not screened further.
Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.

Strongest disproportionality signals

Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 4 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.

Show: hide coding/lab/outcome terms hide indication terms unlabeled only hide PRR-only

Reaction	Reports	PRR 95% CI · ROR · χ²/p	EBGM EB05 · IC025	Label screen	Serious-only & strata	Trial cross-check
Adrenal insufficiency	32	90.9 64.9–127.5ROR 95.8 · χ² 2,751 / p <1e-300	86.2 EB05 63.9 · IC025 +4.7 3/3 methods agree	Not in label — unassessed	serious PRR 56.4 · ♀ 56% (drug 30%) · 97% clinician	no trial data cached
Serotonin syndrome	36	64.0 46.6–87.9ROR 67.9 · χ² 2,167 / p <1e-300	61.9 EB05 46.7 · IC025 +4.5 3/3 methods agree	Not in label — unassessed	serious PRR 39.6 · 97% clinician	no trial data cached
Brain injury	17	57.6 36.0–92.0ROR 59.2 · χ² 888 / p 2e-195	54.2 EB05 35.8 · IC025 +3.6 3/3 methods agree	Not in label — unassessed	serious PRR 35.8	no trial data cached
Drug interaction	181	38.7 34.3–43.8ROR 54.4 · χ² 6,661 / p <1e-300	38.6 EB05 34.1 · IC025 +4.9 3/3 methods agree	Reporting / coding artifact	serious PRR 26.0 · 96% clinician	no trial data cached
Eyelid ptosis	9	30.0 15.7–57.5ROR 30.5 · χ² 224 / p 5e-51	28.3 EB05 15.7 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious n=9	no trial data cached
Anhedonia	20	25.6 16.7–39.5ROR 26.5 · χ² 449 / p 5e-100	25.1 EB05 17.1 · IC025 +3.3 3/3 methods agree	Not in label — unassessed	serious PRR 15.7	no trial data cached
Nerve injury	8	24.4 12.2–48.5ROR 24.7 · χ² 157 / p 3e-36	22.6 EB05 11.4 · IC025 +2.1 3/3 methods agree	Not in label — unassessed	serious PRR 19.4	no trial data cached
Drug level increased	11	22.5 12.5–40.5ROR 22.9 · χ² 205 / p 7e-47	21.5 EB05 12.4 · IC025 +2.5 3/3 methods agree	Reporting / coding artifact	serious PRR 12.5	no trial data cached
Osteopenia	10	22.3 12.0–41.2ROR 22.6 · χ² 182 / p 8e-42	21.1 EB05 11.6 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious PRR 12.9	no trial data cached
Foetal exposure during pregnancy	48	20.1 15.3–26.3ROR 21.7 · χ² 853 / p 8e-188	19.9 EB05 15.6 · IC025 +3.6 3/3 methods agree	Reporting / coding artifact	serious PRR 12.6 · ♀ 76% (drug 30%) · 92% clinician	no trial data cached
Economic problem	8	17.6 8.8–35.1ROR 17.8 · χ² 109 / p 7e-26	15.6 EB05 6.9 · IC025 +1.9 3/3 methods agree	Reporting / coding artifact	serious PRR 10.3	no trial data cached
Product prescribing error	12	17.2 9.8–30.1ROR 17.5 · χ² 167 / p 1e-38	16.2 EB05 9.0 · IC025 +2.4 3/3 methods agree	Reporting / coding artifact	serious PRR 22.1	no trial data cached
Pneumocystis jirovecii pneumonia	5	17.0 7.1–40.7ROR 17.1 · χ² 60 / p 5e-15	12.5 EB05 4.1 · IC025 +1.2 3/3 methods agree	Not in label — unassessed	serious PRR 10.5	no trial data cached
Metabolic acidosis	15	16.1 9.8–26.5ROR 16.5 · χ² 198 / p 4e-45	15.3 EB05 9.2 · IC025 +2.6 3/3 methods agree	Not in label — unassessed	serious PRR 9.9	no trial data cached
Orthostatic hypotension (dizziness on standing)	8	15.6 7.8–31.0ROR 15.8 · χ² 95 / p 1e-22	13.2 EB05 5.8 · IC025 +1.9 3/3 methods agree	Not in label — unassessed	serious PRR 10.9	no trial data cached
Rhabdomyolysis (muscle breakdown)	17	13.9 8.7–22.2ROR 14.2 · χ² 191 / p 1e-43	13.0 EB05 8.0 · IC025 +2.5 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 8.6	no trial data cached
Drug resistance	10	13.2 7.1–24.4ROR 13.4 · χ² 101 / p 4e-24	11.3 EB05 5.6 · IC025 +2.0 3/3 methods agree	Reporting / coding artifact	serious PRR 8.2	no trial data cached
Abortion spontaneous	14	11.8 7.0–19.8ROR 12.1 · χ² 128 / p 5e-30	10.4 EB05 6.0 · IC025 +2.2 3/3 methods agree	Not in label — unassessed	serious PRR 7.3	no trial data cached
Disability	6	10.3 4.6–22.8ROR 10.4 · χ² 41 / p 6e-11	7.0 EB05 3.1 · IC025 +1.2 3/3 methods agree	Not in label — unassessed	serious PRR 6.5	no trial data cached
Osteonecrosis (bone death)	8	8.2 4.1–16.3ROR 8.3 · χ² 44 / p 2e-11	6.1 EB05 3.2 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 5.1	no trial data cached
Premature baby	7	7.9 3.8–16.4ROR 7.9 · χ² 35 / p 1e-9	5.6 EB05 2.8 · IC025 +1.1 3/3 methods agree	Not in label — unassessed	serious PRR 4.9	no trial data cached
Bone density decreased	7	7.5 3.6–15.7ROR 7.6 · χ² 33 / p 4e-9	5.4 EB05 2.8 · IC025 +1.1 3/3 methods agree	Lab value / disease marker	serious PRR 4.1	no trial data cached

Trial evidence (ClinicalTrials.gov)

Trial cross-check not yet run for this drug (ClinicalTrials.gov pull covers the 800 most-reported drugs first).

Most frequently reported reactions

By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.

Reaction	Reports	PRR 95% CI · ROR · χ²/p	EBGM EB05 · IC025	Label screen	Serious-only & strata	Trial cross-check
Drug interaction	181	38.7 34.3–43.8ROR 54.4 · χ² 6,661 / p <1e-300	38.6 EB05 34.1 · IC025 +4.9 3/3 methods agree	Reporting / coding artifact	serious PRR 26.0 · 96% clinician	no trial data cached
Foetal exposure during pregnancy	48	20.1 15.3–26.3ROR 21.7 · χ² 853 / p 8e-188	19.9 EB05 15.6 · IC025 +3.6 3/3 methods agree	Reporting / coding artifact	serious PRR 12.6 · ♀ 76% (drug 30%) · 92% clinician	no trial data cached
Serotonin syndrome	36	64.0 46.6–87.9ROR 67.9 · χ² 2,167 / p <1e-300	61.9 EB05 46.7 · IC025 +4.5 3/3 methods agree	Not in label — unassessed	serious PRR 39.6 · 97% clinician	no trial data cached
Adrenal insufficiency	32	90.9 64.9–127.5ROR 95.8 · χ² 2,751 / p <1e-300	86.2 EB05 63.9 · IC025 +4.7 3/3 methods agree	Not in label — unassessed	serious PRR 56.4 · ♀ 56% (drug 30%) · 97% clinician	no trial data cached
Anhedonia	20	25.6 16.7–39.5ROR 26.5 · χ² 449 / p 5e-100	25.1 EB05 17.1 · IC025 +3.3 3/3 methods agree	Not in label — unassessed	serious PRR 15.7	no trial data cached
Rhabdomyolysis (muscle breakdown)	17	13.9 8.7–22.2ROR 14.2 · χ² 191 / p 1e-43	13.0 EB05 8.0 · IC025 +2.5 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 8.6	no trial data cached
Brain injury	17	57.6 36.0–92.0ROR 59.2 · χ² 888 / p 2e-195	54.2 EB05 35.8 · IC025 +3.6 3/3 methods agree	Not in label — unassessed	serious PRR 35.8	no trial data cached
Metabolic acidosis	15	16.1 9.8–26.5ROR 16.5 · χ² 198 / p 4e-45	15.3 EB05 9.2 · IC025 +2.6 3/3 methods agree	Not in label — unassessed	serious PRR 9.9	no trial data cached
Abortion spontaneous	14	11.8 7.0–19.8ROR 12.1 · χ² 128 / p 5e-30	10.4 EB05 6.0 · IC025 +2.2 3/3 methods agree	Not in label — unassessed	serious PRR 7.3	no trial data cached
Product prescribing error	12	17.2 9.8–30.1ROR 17.5 · χ² 167 / p 1e-38	16.2 EB05 9.0 · IC025 +2.4 3/3 methods agree	Reporting / coding artifact	serious PRR 22.1	no trial data cached
Drug level increased	11	22.5 12.5–40.5ROR 22.9 · χ² 205 / p 7e-47	21.5 EB05 12.4 · IC025 +2.5 3/3 methods agree	Reporting / coding artifact	serious PRR 12.5	no trial data cached
Drug resistance	10	13.2 7.1–24.4ROR 13.4 · χ² 101 / p 4e-24	11.3 EB05 5.6 · IC025 +2.0 3/3 methods agree	Reporting / coding artifact	serious PRR 8.2	no trial data cached
Osteopenia	10	22.3 12.0–41.2ROR 22.6 · χ² 182 / p 8e-42	21.1 EB05 11.6 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious PRR 12.9	no trial data cached
Eyelid ptosis	9	30.0 15.7–57.5ROR 30.5 · χ² 224 / p 5e-51	28.3 EB05 15.7 · IC025 +2.4 3/3 methods agree	Not in label — unassessed	serious n=9	no trial data cached
Osteonecrosis (bone death)	8	8.2 4.1–16.3ROR 8.3 · χ² 44 / p 2e-11	6.1 EB05 3.2 · IC025 +1.3 3/3 methods agree	Not in label — unassessed	serious PRR 5.1	no trial data cached

Unlabeled candidate signals

These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.

Adrenal insufficiency — n=32, PRR 90.9
Serotonin syndrome — n=36, PRR 64.0
Anhedonia — n=20, PRR 25.6

Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.

Common questions

What are the most reported side effects of Cobicistat?

In FDA FAERS, the most frequently co-reported reaction terms for Cobicistat are serotonin syndrome, adrenal insufficiency, anhedonia, rhabdomyolysis, brain injury, metabolic acidosis. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.

Does Cobicistat have an FDA boxed warning?

No. The FDA label retrieved for Cobicistat has no boxed warning; see the label's Warnings and Precautions for the recognised risks.

Do FAERS signals prove that Cobicistat causes these side effects?

No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.

Sources & methods

FDA label via openFDA (set ID 3784c35c-e87f-410c-900b-8fd6313c6010, effective 20260210; matched on openfda.generic_name.exact:"COBICISTAT")
Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA count= aggregation, field patient.drug.openfda.generic_name.exact, 26 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction
Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
Seriousness and sex counts from openFDA count=serious, patient.patientsex, seriousnessdeath

Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.