Drugs › Cytochrome P450 3A inhibitor
Generic name
Ritonavir: adverse event reports filed with FDA
11,399 reports list it as a suspect or interacting product, 2004–2026. Class: Cytochrome P450 3A inhibitor. Also reported as Ritonavir Oral Solution, Ritonavir Capsules, Ritonavir Tablet.
- 11,399
- reports as suspect product
- 0.1% of all reports · about 507 a year
- 164
- reports, 12 months to June 2026
- 292 in the 12 months before
- 92%
- marked serious by the reporter
- 87.2% across the class
- 9.2%
- record death among outcomes, as reported
- 1,051 reports · not verified by FDA
Between January 2004 and June 2026, 11,399 adverse event reports received by FDA list ritonavir, a generic name as a suspect or interacting product. Reports that mention it only as a concomitant medication (3,730) are left out of every figure here.
In the 12 months to June 2026, 164 reports listed it, down 44% from 292 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Over its reporting history that is about 507 reports a year and 0.1% of the 20,646,523 reports in the database, and 24.6% of the reports for the cytochrome P450 3A inhibitor class. How many people take it is not in the data, so a count is not a rate of occurrence.
Reporters most often recorded drug interaction (16.8%), foetal exposure during pregnancy (11.1%) and maternal exposure during pregnancy (5.6%). A report can list several reactions, so shares add to more than 100%; 1,691 different terms appear across these reports. Drug interaction is recorded in 16.8% of these reports, a larger share than in the median cytochrome P450 3A inhibitor drug (7.1%).
92% of the reports are marked serious by the reporter (87.2% across the class); 9.2% record death among the outcomes and 26.8% record hospitalisation, as reported. 51.8% of the reports came from other health professionals, and the largest patient age group is 18 to 44 (23.4%). FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event."
Reports by month, five years
Reports by the month FDA received them. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.
By year received
2026 covers reports received through June 2026 only.
Reactions recorded in the reports
share of Ritonavir reports recording the termmedian drug in cytochrome p450 3a inhibitor
- Drug interactionan interaction between medicines16.8%1,919
- Foetal exposure during pregnancythe unborn baby was exposed to the medicine11.1%1,260
- Maternal exposure during pregnancythe mother took the medicine during pregnancy5.6%635
- Exposure during pregnancythe medicine was taken during pregnancy5.5%624
- Virologic failure4.9%563
- Drug resistance4.3%494
- Premature babya baby born early3.7%426
- Toxicity to various agentspoisoning or toxic effect of one or more substances3.7%425
- Off label useused for a purpose or in a way not on the label3.6%410
- Diarrhoealoose or frequent stools3.4%383
- Cushing's syndrome3.3%371
- Nauseafeeling sick3.2%367
- Abortion spontaneousmiscarriage3.2%364
- Acute kidney injurysudden loss of kidney function3.2%360
- Anaemialow red blood cells2.4%277
- Treatment failurethe treatment did not work2.4%275
- Premature delivery2.4%273
- Vomitingbeing sick2.4%272
- Deaththe patient died; cause not stated by this term2.4%271
- Fatiguetiredness2.4%268
- Drug ineffectivethe medicine did not work as expected2.3%258
- Treatment noncompliancethe treatment was not taken as directed2.1%244
- Lipodystrophy acquiredchanges in body fat distribution2%232
- Pyrexiafever2%227
- Headachehead pain1.9%214
- Alanine aminotransferase increasedraised liver enzyme (ALT)1.8%210
- Pathogen resistance1.8%208
- Anxietyanxiety1.7%195
- Viral mutation identified1.7%189
- Depressionlow mood1.6%184
Top 30 of 1,691 MedDRA preferred terms recorded across these reports, with a plain-language gloss where one is available. One report can record several terms. The hollow bar is the median share across the 8 drugs in the cytochrome p450 3a inhibitor class; it describes the reports, not the patients. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Outcomes recorded
Outcome flags as the reporter set them; a report can carry several, and "other serious" is FDA's own category for serious reports outside the named outcomes. Grey bar: all 46,425 reports in the class. FDA has not verified any outcome and states that the reports "cannot be used to estimate the incidence of these events."
Patients and reporters
Patient age
Patient sex
Who reported
Age and sex as stated in the report; the reporter's qualification is the primary source recorded by FDA. 34.3% of reports give the United States as the country of the event or reporter.
Reason for use recorded
| Indication as recorded (MedDRA) | Reports | Share |
|---|---|---|
| Hiv infection | 6,269 | 55% |
| Covid-19 | 546 | 4.8% |
| Antiretroviral therapy | 505 | 4.4% |
| Maternal exposure timing unspecified | 242 | 2.1% |
| Hepatitis c | 171 | 1.5% |
| Chronic hepatitis c | 119 | 1% |
The indication field is filled in by the reporter and is often blank; shares are of all 11,399 reports.
Drugs most often listed in the same reports
| Drug (any role in the report) | Reports | Share of Ritonavir reports |
|---|---|---|
| Darunavir | 3,465 | 30.4% |
| Lamivudine | 2,607 | 22.9% |
| Atazanavir | 1,910 | 16.8% |
| Zidovudine | 1,651 | 14.5% |
| Lopinavir | 1,381 | 12.1% |
| Tenofovir | 1,301 | 11.4% |
| Emtricitabine | 1,191 | 10.4% |
| Raltegravir | 1,106 | 9.7% |
| Truvada | 1,100 | 9.6% |
| Abacavir | 1,054 | 9.2% |
Other products listed in reports where Ritonavir is a suspect product, whatever their own role. Co-listing means the two were recorded together; it says nothing about either product's part in the event. Only the 2,500 most-reported names are counted here.
In context
| Measure | Ritonavir | Cytochrome P450 3A inhibitor | All reports |
|---|---|---|---|
| Reports as suspect product | 11,399 | 46,425 | 20,646,523 |
| Share of that pool | — | 24.6% | 0.1% |
| Reports, latest 12 months | 164 | — | 1,332,454 |
| Marked serious | 92% | 87.2% | 57.4% |
| Death recorded among outcomes, per 1,000 reports | 92 | 90 | 91 |
| Hospitalisation recorded, per 1,000 reports | 268 | 260 | 213 |
| Consumer-filed share | 12.2% | 15.9% | 45.8% |
| Top term, share of reports | Drug interaction 16.8% | median 7.1% | 0.8% |
Shares are of reports, not of patients treated. The number of people taking a product is not in the data, so none of these figures is a rate, and differences between columns reflect who takes a product, who reports and how long it has been sold. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."
Other drugs in the cytochrome p450 3a inhibitor class
| Drug | Name type | Reports | Latest 12 months | Marked serious |
|---|---|---|---|---|
| Kaletra | brand | 9,419 | 57 | 92.5% |
| Norvir | brand | 8,821 | 44 | 92.8% |
| Stribild | brand | 8,754 | 124 | 86.3% |
| Lopinavir and ritonavir | generic | 3,003 | 9 | 96.7% |
| Genvoya | brand | 2,994 | 57 | 50.6% |
| Symtuza | brand | 1,067 | 64 | 56.8% |
| Prezcobix | brand | 968 | 27 | 54.4% |
Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." A brand and its generic are separate rows because reporters name them separately.
Questions about Ritonavir reports
How many adverse event reports has FDA received for Ritonavir?
11,399 reports list Ritonavir as a suspect or interacting product in the openFDA FAERS release of 28 Sep 2026, covering reports received through June 2026. 164 of them arrived in the latest 12 months. Another 3,730 list it only as a concomitant medication.
What reactions are recorded in Ritonavir reports?
drug interaction (16.8%), foetal exposure during pregnancy (11.1%), maternal exposure during pregnancy (5.6%), exposure during pregnancy (5.5%) and virologic failure (4.9%). These are MedDRA preferred terms coded from what the reporter described; a report can list several, and a term's presence is not a finding that Ritonavir was responsible.
How serious are the reports?
92% are marked serious by the reporter. Among the outcomes recorded, 9.2% of reports include death and 26.8% include hospitalisation. FDA has not verified these outcomes and states that the reports "cannot be used to estimate the incidence" of the events.
Who files these reports?
other health professional (51.8%), physician (27.3%) and consumer or non-health professional (12.2%). Most reports reach FDA through the manufacturer, which must forward reports it receives.
Are reports for Ritonavir rising?
164 reports in the 12 months to June 2026, down 44% from 292 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. Counts also move with how many people take a product, its time on the market and publicity.
Do these reports show that Ritonavir was responsible for these reactions?
No. FDA states that "a causal relationship cannot be established between product and reactions listed in a report" and that for any given report "there is no certainty that a suspected drug caused the event." The reaction may relate to the condition being treated, to other medicines, or to something else.
Is this a list of the side effects of Ritonavir?
No. It is a count of what was reported to FDA. The adverse reactions observed in clinical studies are printed on the FDA-approved label, which a pharmacist or clinician can go through with you.
How do I report an adverse event?
Consumers and health professionals can report to FDA through MedWatch (Form FDA 3500 online, or 1-800-FDA-1088), or to the manufacturer, which must pass reports on. See the guide on how to report.
Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A report counts here when it lists Ritonavir as a suspect or interacting product; reports listing it only as a concomitant medication (3,730) are excluded. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.
Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.