Clarithromycin side effects: what 34,129 FDA adverse event reports show

Clarithromycin · 1,227 reaction terms · 141,931 drug–reaction co-reports · data 2026-09-14

Drug class

Macrolide Antimicrobial

FDA label (Established Pharmacologic Class)

Who reports

34,129 reports · 92% serious · 2,961 with death outcome · 60% female

openFDA FAERS counts, all years, deduplication not applied

Used for

Clarithromycin is a macrolide antimicrobial indicated for mild to moderate infections caused by designated, susceptible bacteria in the following: Acute Bacterial Exacerbation of Chronic Bronchitis in Adults ( 1.1 ) Acute Maxillary Sinusitis ( 1.2 ) Co.

FDA label, Indications and Usage

What it is

Clarithromycin is a semi-synthetic macrolide antimicrobial for oral use.

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 40 strongest signals

Labeled adverse reaction 1Labeled (related wording) 5Likely indication confounding 11Reporting / coding artifact 3Lab value / disease marker 2Not in label — unassessed 18

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.
Labeled (related wording) The label describes this effect under different wording (e.g. 'neutropenia' for 'neutrophil count decreased'). Treated as known.
Likely indication confounding The term appears in the label's indications: reports probably describe the disease being treated (or its progression), not a drug effect. Classic confounding by indication.
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. 1,187 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
Vaginal flatulence	174	822.7 655.0–1,033.4ROR 826.9 · χ² 60,179 / p <1e-300	336.3 EB05 296.4 · IC025 +7.2 3/3 methods agree	Labeled (related wording) related wording	serious n=174 · ♀ 100% (drug 60%)	no trial arm names this drug
Salpingo-oophorectomy unilateral	33	262.8 174.7–395.4ROR 263.0 · χ² 5,819 / p <1e-300	166.1 EB05 123.7 · IC025 +5.0 3/3 methods agree	Not in label — unassessed	serious n=33 · ♀ 100% (drug 60%) · 100% clinician	no trial arm names this drug
Mycobacterial peritonitis	23	193.3 120.9–309.1ROR 193.5 · χ² 3,191 / p <1e-300	131.0 EB05 92.0 · IC025 +4.5 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious n=23	no trial arm names this drug
Neuropsychiatric lupus	25	164.5 105.7–255.9ROR 164.6 · χ² 3,066 / p <1e-300	118.1 EB05 84.1 · IC025 +4.5 3/3 methods agree	Not in label — unassessed	serious n=25 · ♀ 0% (drug 60%) · 100% clinician	no trial arm names this drug
Personality change due to a general medical condition	24	145.3 93.0–226.8ROR 145.4 · χ² 2,657 / p <1e-300	107.5 EB05 76.0 · IC025 +4.4 3/3 methods agree	Not in label — unassessed	serious n=24 · 100% consumer	no trial arm names this drug
Mycobacterium fortuitum infection	24	91.4 59.5–140.3ROR 91.4 · χ² 1,786 / p <1e-300	74.9 EB05 53.0 · IC025 +4.3 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious n=24 · ♀ 0% (drug 60%)	no trial arm names this drug
Female genital tract fistula	220	90.0 78.2–103.7ROR 90.6 · χ² 16,784 / p <1e-300	78.0 EB05 69.7 · IC025 +5.8 3/3 methods agree	Not in label — unassessed	serious n=220 · ♀ 100% (drug 60%)	no trial arm names this drug
Mycobacterium chelonae infection	89	84.4 67.7–105.4ROR 84.6 · χ² 6,366 / p <1e-300	73.1 EB05 61.2 · IC025 +5.4 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious n=86 · 92% clinician	no trial arm names this drug
Mycobacterium abscessus infection	77	75.3 59.4–95.4ROR 75.5 · χ² 4,954 / p <1e-300	66.0 EB05 54.5 · IC025 +5.2 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious n=77 · 100% clinician	no trial arm names this drug
Hepatic ischaemia	29	62.9 42.9–92.2ROR 63.0 · χ² 1,545 / p <1e-300	55.1 EB05 40.3 · IC025 +4.3 3/3 methods agree	Not in label — unassessed	serious n=29 · ♀ 100% (drug 60%) · 100% clinician	no trial arm names this drug
Mycobacterium haemophilum infection	23	61.1 39.8–93.7ROR 61.1 · χ² 1,180 / p 7e-259	53.2 EB05 37.4 · IC025 +4.0 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious n=23	no trial arm names this drug
Chronic sinusitis	302	53.8 47.9–60.5ROR 54.3 · χ² 14,331 / p <1e-300	49.4 EB05 44.9 · IC025 +5.3 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious n=298 · ♀ 95% (drug 60%)	no trial arm names this drug
Soft tissue mass	34	48.8 34.4–69.1ROR 48.8 · χ² 1,428 / p <1e-300	44.2 EB05 33.1 · IC025 +4.2 3/3 methods agree	Not in label — unassessed	serious n=34 · ♀ 0% (drug 60%) · 100% clinician	no trial arm names this drug
Radiculopathy	181	45.2 38.9–52.6ROR 45.5 · χ² 7,244 / p <1e-300	42.0 EB05 37.1 · IC025 +5.0 3/3 methods agree	Not in label — unassessed	serious n=181 · ♀ 100% (drug 60%)	no trial arm names this drug
Macular degeneration	815	45.1 42.0–48.3ROR 46.1 · χ² 32,658 / p <1e-300	42.0 EB05 39.6 · IC025 +5.2 3/3 methods agree	Not in label — unassessed	serious PRR 28.4 · ♀ 100% (drug 60%)	no trial arm names this drug
Atypical mycobacterial infection	92	43.4 35.1–53.6ROR 43.5 · χ² 3,517 / p <1e-300	40.3 EB05 33.8 · IC025 +4.7 3/3 methods agree	Labeled (related wording) related wording	serious n=92 · 93% clinician	no trial arm names this drug
Mycobacterial infection	111	42.3 34.9–51.2ROR 42.4 · χ² 4,143 / p <1e-300	39.3 EB05 33.6 · IC025 +4.8 3/3 methods agree	Likely indication confounding term in indications; also in warnings	serious n=110 · ♀ 38% (drug 60%) · 90% clinician	no trial arm names this drug
Proctitis	175	40.8 35.1–47.6ROR 41.1 · χ² 6,336 / p <1e-300	38.2 EB05 33.7 · IC025 +4.9 3/3 methods agree	Not in label — unassessed	serious n=175 · ♀ 100% (drug 60%)	no trial arm names this drug
Mycobacterium avium complex infection	164	40.3 34.4–47.2ROR 40.5 · χ² 5,857 / p <1e-300	37.7 EB05 33.1 · IC025 +4.8 3/3 methods agree	Labeled (related wording) related wording	serious n=161	no trial arm names this drug
Sinusitis fungal	41	33.7 24.6–46.1ROR 33.7 · χ² 1,200 / p 3e-263	31.5 EB05 24.2 · IC025 +4.0 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious n=41 · ♀ 100% (drug 60%) · 100% clinician	no trial arm names this drug
Pathogen resistance	457	32.4 29.5–35.6ROR 32.9 · χ² 13,193 / p <1e-300	30.8 EB05 28.5 · IC025 +4.7 3/3 methods agree	Reporting / coding artifact	serious PRR 20.3 · 100% clinician	no trial arm names this drug
Tachycardia foetal	24	31.2 20.7–47.1ROR 31.3 · χ² 640 / p 2e-141	29.1 EB05 20.6 · IC025 +3.5 3/3 methods agree	Labeled (related wording) related wording	serious n=24 · ♀ 0% (drug 60%)	no trial arm names this drug
Immunosuppressant drug level increased	155	30.3 25.8–35.6ROR 30.4 · χ² 4,155 / p <1e-300	28.8 EB05 25.2 · IC025 +4.5 3/3 methods agree	Lab value / disease marker	serious n=154 · ♀ 26% (drug 60%) · 95% clinician	no trial arm names this drug
Pneumonia mycoplasmal	37	29.9 21.5–41.6ROR 30.0 · χ² 959 / p 8e-211	28.2 EB05 21.4 · IC025 +3.8 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious n=37 · 100% clinician	no trial arm names this drug
Ototoxicity	86	29.8 24.0–37.0ROR 29.9 · χ² 2,258 / p <1e-300	28.3 EB05 23.7 · IC025 +4.3 3/3 methods agree	Not in label — unassessed	serious n=86	no trial arm names this drug
Oesophageal perforation	37	28.6 20.5–39.7ROR 28.6 · χ² 914 / p 5e-201	27.0 EB05 20.4 · IC025 +3.8 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious n=37 · ♀ 0% (drug 60%) · 100% clinician	no trial arm names this drug
Labelled drug-drug interaction medication error	373	26.8 24.1–29.7ROR 27.0 · χ² 8,838 / p <1e-300	25.6 EB05 23.5 · IC025 +4.5 3/3 methods agree	Reporting / coding artifact	serious PRR 19.1	no trial arm names this drug
Helicobacter gastritis	50	25.6 19.3–34.0ROR 25.6 · χ² 1,111 / p 8e-244	24.4 EB05 19.2 · IC025 +3.8 3/3 methods agree	Likely indication confounding shares a disease stem with the indications wording	serious n=49 · ♀ 0% (drug 60%)	no trial arm names this drug
Enterocolitis haemorrhagic	58	24.9 19.2–32.4ROR 24.9 · χ² 1,255 / p 4e-275	23.8 EB05 19.1 · IC025 +3.9 3/3 methods agree	Not in label — unassessed	serious n=58 · 100% clinician	no trial arm names this drug
Contraindicated drug administered	27	24.3 16.5–35.7ROR 24.3 · χ² 557 / p 2e-123	23.0 EB05 16.6 · IC025 +3.4 3/3 methods agree	Reporting / coding artifact	serious n=27	no trial arm names this drug
Superinfection	56	23.8 18.2–31.0ROR 23.8 · χ² 1,153 / p 4e-253	22.8 EB05 18.2 · IC025 +3.8 3/3 methods agree	Not in label — unassessed	serious n=56 · ♀ 36% (drug 60%) · 100% clinician	no trial arm names this drug
Cardioactive drug level increased	48	23.0 17.2–30.7ROR 23.0 · χ² 952 / p 2e-209	22.0 EB05 17.3 · IC025 +3.7 3/3 methods agree	Lab value / disease marker	serious n=48 · 100% clinician	no trial arm names this drug
Pressure of speech	23	22.5 14.8–34.1ROR 22.5 · χ² 435 / p 7e-97	21.4 EB05 14.9 · IC025 +3.2 3/3 methods agree	Not in label — unassessed	serious n=23	no trial arm names this drug
Acute psychosis	85	21.9 17.6–27.1ROR 21.9 · χ² 1,614 / p <1e-300	21.1 EB05 17.6 · IC025 +3.9 3/3 methods agree	Not in label — unassessed	serious n=85 · 90% clinician	no trial arm names this drug
Pulmonary cavitation	27	19.8 13.5–29.0ROR 19.8 · χ² 448 / p 9e-100	18.9 EB05 13.6 · IC025 +3.2 3/3 methods agree	Not in label — unassessed	serious n=27 · 100% clinician	no trial arm names this drug
Lip erosion	23	19.8 13.1–29.9ROR 19.8 · χ² 379 / p 1e-84	18.8 EB05 13.1 · IC025 +3.1 3/3 methods agree	Not in label — unassessed	serious n=23	no trial arm names this drug
Hypocoagulable state	30	19.4 13.5–27.9ROR 19.4 · χ² 489 / p 1e-108	18.6 EB05 13.6 · IC025 +3.3 3/3 methods agree	Not in label — unassessed	serious n=30 · ♀ 0% (drug 60%) · 100% clinician	no trial arm names this drug
Pseudomembranous colitis	68	19.2 15.1–24.4ROR 19.2 · χ² 1,118 / p 2e-245	18.5 EB05 15.1 · IC025 +3.6 3/3 methods agree	Labeled adverse reaction exact term	serious n=67 · 100% clinician	no trial arm names this drug
Long qt syndrome	72	18.9 14.9–23.9ROR 18.9 · χ² 1,166 / p 7e-256	18.3 EB05 15.0 · IC025 +3.6 3/3 methods agree	Labeled (related wording) related wording	serious n=72 · 100% clinician	no trial arm names this drug
Immune reconstitution syndrome	39	18.9 13.7–25.9ROR 18.9 · χ² 622 / p 1e-137	18.1 EB05 13.8 · IC025 +3.4 3/3 methods agree	Not in label — unassessed	serious n=39 · ♀ 0% (drug 60%) · 100% clinician	no trial arm names this drug

Trial evidence (ClinicalTrials.gov)

ClinicalTrials.gov returned results-bearing trials mentioning Clarithromycin only as a background or rescue medication (NCT01095978, NCT04167670); no trial listing it as the tested intervention was cached, so no trial cross-check is shown.

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	2,994	11.8 11.4–12.2ROR 12.8 · χ² 29,234 / p <1e-300	11.6 EB05 11.2 · IC025 +3.5 3/3 methods agree	Reporting / coding artifact	serious PRR 8.0 · 92% clinician	no trial arm names this drug
Drug ineffective (drug did not work)	2,569	1.2 1.2–1.2ROR 1.2 · χ² 90 / p 1e-21	1.2 EB05 1.2 · IC025 +0.2	Reporting / coding artifact	serious PRR 2.0	no trial arm names this drug
Nausea	2,291	1.8 1.7–1.9ROR 1.8 · χ² 821 / p 9e-181	1.8 EB05 1.7 · IC025 +0.8	Labeled adverse reaction exact term	serious PRR 2.0	no trial arm names this drug
Dyspnoea (shortness of breath)	2,020	2.2 2.1–2.3ROR 2.3 · χ² 1,350 / p 8e-296	2.2 EB05 2.1 · IC025 +1.1 3/3 methods agree	Not in label — unassessed	serious PRR 1.9	no trial arm names this drug
Diarrhoea (diarrhea)	1,994	1.9 1.8–2.0ROR 2.0 · χ² 884 / p 1e-194	1.9 EB05 1.8 · IC025 +0.9	Labeled adverse reaction exact term	serious PRR 2.0	no trial arm names this drug
Malaise (feeling unwell)	1,694	2.4 2.3–2.5ROR 2.4 · χ² 1,368 / p 1e-299	2.4 EB05 2.3 · IC025 +1.2 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 2.4	no trial arm names this drug
Pyrexia (fever)	1,651	2.9 2.8–3.1ROR 3.0 · χ² 2,135 / p <1e-300	2.9 EB05 2.8 · IC025 +1.5 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 2.3	no trial arm names this drug
Off label use (used outside approved label)	1,619	1.1 1.1–1.2ROR 1.2 · χ² 31 / p 1e-8	1.1 EB05 1.1 · IC025 +0.1	Reporting / coding artifact	serious PRR 1.2	no trial arm names this drug
Headache	1,610	1.6 1.5–1.7ROR 1.6 · χ² 353 / p 5e-79	1.6 EB05 1.5 · IC025 +0.6	Labeled adverse reaction exact term	serious PRR 1.9 · ♀ 81% (drug 60%)	no trial arm names this drug
Vomiting	1,504	2.0 1.9–2.1ROR 2.0 · χ² 736 / p 2e-162	2.0 EB05 1.9 · IC025 +0.9	Labeled adverse reaction exact term	serious PRR 1.8	no trial arm names this drug
Rash	1,284	1.8 1.7–1.9ROR 1.9 · χ² 484 / p 2e-107	1.8 EB05 1.7 · IC025 +0.8	Labeled adverse reaction exact term	serious PRR 2.3	no trial arm names this drug
Pneumonia (lung infection)	1,260	2.4 2.3–2.5ROR 2.5 · χ² 1,040 / p 2e-228	2.4 EB05 2.3 · IC025 +1.2 3/3 methods agree	Likely indication confounding term in indications	serious PRR 1.6	no trial arm names this drug
Dizziness	1,224	1.5 1.4–1.6ROR 1.5 · χ² 216 / p 3e-49	1.5 EB05 1.4 · IC025 +0.5	Labeled adverse reaction exact term	serious PRR 1.6	no trial arm names this drug
Fatigue (tiredness)	1,197	0.9 0.9–1.0ROR 0.9 · χ² 4 / p 0.027	0.9 EB05 0.9 · IC025 -0.2 PRR-only: not supported by EBGM or IC	Labeled adverse reaction exact term	serious PRR 1.0	no trial arm names this drug
Abdominal pain	1,050	2.8 2.6–3.0ROR 2.8 · χ² 1,205 / p 2e-264	2.8 EB05 2.6 · IC025 +1.4 3/3 methods agree	Labeled adverse reaction exact term	serious PRR 2.2	no trial arm names this drug

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.

Salpingo-oophorectomy unilateral — n=33, PRR 262.8
Neuropsychiatric lupus — n=25, PRR 164.5
Personality change due to a general medical condition — n=24, PRR 145.3
Female genital tract fistula — n=220, PRR 90.0
Hepatic ischaemia — n=29, PRR 62.9
Soft tissue mass — n=34, PRR 48.8
Radiculopathy — n=181, PRR 45.2
Macular degeneration — n=815, PRR 45.1
Proctitis — n=175, PRR 40.8
Ototoxicity — n=86, PRR 29.8

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 Clarithromycin?

In FDA FAERS, the most frequently co-reported reaction terms for Clarithromycin are nausea, dyspnoea, diarrhoea, malaise, pyrexia, headache. 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 Clarithromycin have an FDA boxed warning?

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

Do FAERS signals prove that Clarithromycin 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 0be243c6-de02-45dd-8210-cab1bbc8dfa7, effective 20251015; matched on openfda.generic_name.exact:"CLARITHROMYCIN")
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, 1,227 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
ClinicalTrials.gov API v2 (query CLARITHROMYCIN, results-bearing studies sorted by enrollment)

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.