Azithromycin side effects: what 39,997 FDA adverse event reports show
Drug class
Macrolide antibacterial drug
Who reports
39,997 reports · 78% serious · 3,880 with death outcome · 59% female
Used for
Azithromycin tablet is a macrolide antibacterial drug indicated for treatment of patients with mild to moderate infections caused by susceptible strains of the designated microorganisms in the specific conditions listed below: Acute bacterial exacerbat.
What it is
Azithromycin tablets USP contain the active ingredient azithromycin, a macrolide antibacterial drug, for oral administration. Azithromycin has the chemical name (2R,3S,4R,5R,8R,10R,11R,12S,13S.
Boxed warning
None in the current label
Causality screen of the 40 strongest signals
What the badges mean
- 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, for the 300 most-reported drugs, adjusted for age band), and flags pairs whose reports are unusually skewed by sex or come mostly from consumers. Each row also shows the PRR against the other drugs of the same FDA class, which removes most confounding by the condition being treated, and a calibrated p-value: on validation, known non-causes average an ROR of about 2, so significance is judged against that empirical null (✓ = p < 0.05 after calibration). 1,195 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Normal labour | 123 | 3,968.3 2,357.3–6,680.1ROR 3,980.5 · calibrated p 2e-22 ✓ | 427.1 EB05 367.4 · IC025 +7.0 3/3 methods agree | Not in label — unassessed | serious n=123 · ♀ 100% (drug 59%) · 90% clinician | not reported in cached trials |
| Vaginal flatulence | 154 | 537.1 428.7–672.9ROR 539.2 · calibrated p 5e-14 ✓ | 255.4 EB05 223.3 · IC025 +6.9 3/3 methods agree | Not in label — unassessed | serious n=154 · ♀ 100% (drug 59%) | not reported in cached trials |
| Congenital hiatus hernia | 106 | 484.2 371.6–631.1ROR 485.5 · calibrated p 2e-13 ✓ | 239.5 EB05 203.7 · IC025 +6.5 3/3 methods agree | Not in label — unassessed | serious n=106 · ♀ 0% (drug 59%) | not reported in cached trials |
| Total lung capacity increased | 118 | 400.7 315.1–509.6ROR 401.9 · calibrated p 1e-12 ✓ | 218.1 EB05 187.0 · IC025 +6.6 3/3 methods agree | Not in label — unassessed | serious n=118 · ♀ 100% (drug 59%) | not reported in cached trials |
| Heart sounds | 40 | 368.7 245.8–553.2ROR 369.1 · calibrated p 8e-12 ✓ | 195.5 EB05 149.7 · IC025 +5.4 3/3 methods agree | Not in label — unassessed | serious n=40 · ♀ 100% (drug 59%) | not reported in cached trials |
| Pulmonary vasculitis | 169 | 247.1 205.8–296.8ROR 248.2 · calibrated p 8e-11 ✓ | 164.4 EB05 144.6 · IC025 +6.6 3/3 methods agree | Not in label — unassessed | serious n=169 · ♀ 0% (drug 59%) | not reported in cached trials |
| Asthma-chronic obstructive pulmonary disease overlap syndrome | 154 | 220.8 182.9–266.6ROR 221.7 · calibrated p 2e-10 ✓ | 152.1 EB05 133.0 · IC025 +6.4 3/3 methods agree | Not in label — unassessed | serious n=154 · ♀ 80% (drug 59%) | not reported in cached trials |
| Total lung capacity abnormal | 107 | 205.3 164.2–256.8ROR 205.9 · calibrated p 5e-10 ✓ | 143.5 EB05 122.1 · IC025 +6.1 3/3 methods agree | Not in label — unassessed | serious n=107 · ♀ 0% (drug 59%) | not reported in cached trials |
| Delivery | 126 | 123.2 101.5–149.6ROR 123.6 · calibrated p 3e-8 ✓ | 98.2 EB05 84.6 · IC025 +5.9 3/3 methods agree | Not in label — unassessed | serious n=126 · ♀ 100% (drug 59%) | not reported in cached trials |
| Capillaritis | 50 | 120.0 88.3–163.3ROR 120.2 · calibrated p 5e-8 ✓ | 94.2 EB05 74.2 · IC025 +5.2 3/3 methods agree | Not in label — unassessed | serious n=50 · ♀ 0% (drug 59%) | not reported in cached trials |
| Spirometry abnormal | 102 | 110.2 89.0–136.4ROR 110.4 · calibrated p 7e-8 ✓ | 89.5 EB05 75.8 · IC025 +5.7 3/3 methods agree | Lab value / disease marker | serious n=102 · ♀ 0% (drug 59%) | not reported in cached trials |
| Prolonged expiration | 43 | 101.8 73.4–141.2ROR 101.9 · calibrated p 2e-7 ✓ | 82.2 EB05 63.6 · IC025 +4.9 3/3 methods agree | Not in label — unassessed | serious n=43 · ♀ 100% (drug 59%) | not reported in cached trials |
| Disseminated mycobacterium avium complex infection | 34 | 99.7 69.1–143.9ROR 99.8 · calibrated p 3e-7 ✓ | 80.1 EB05 59.9 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious n=34 · 100% clinician | not reported in cached trials |
| Mite allergy | 100 | 97.4 78.7–120.6ROR 97.6 · calibrated p 2e-7 ✓ | 80.9 EB05 68.4 · IC025 +5.5 3/3 methods agree | Not in label — unassessed | serious n=99 · ♀ 0% (drug 59%) | not reported in cached trials |
| Babesiosis | 38 | 82.1 58.3–115.6ROR 82.2 · calibrated p 1e-6 ✓ | 68.6 EB05 52.2 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious n=38 · ♀ 0% (drug 59%) · 100% clinician | not reported in cached trials |
| Mycobacterium abscessus infection | 85 | 71.8 57.2–90.1ROR 72.0 · calibrated p 2e-6 ✓ | 62.3 EB05 52.0 · IC025 +5.2 3/3 methods agree | Not in label — unassessed | serious n=84 · 100% clinician | not reported in cached trials |
| Mycobacterium avium complex infection | 309 | 68.8 61.1–77.5ROR 69.3 · calibrated p 2e-6 ✓ | 60.6 EB05 55.2 · IC025 +5.6 3/3 methods agree | Not in label — unassessed | serious n=298 | not reported in cached trials |
| Bronchopulmonary aspergillosis allergic | 105 | 67.8 55.3–83.0ROR 67.9 · calibrated p 2e-6 ✓ | 59.4 EB05 50.5 · IC025 +5.2 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=105 | not reported in cached trials |
| Mycotic allergy | 96 | 67.3 54.4–83.3ROR 67.5 · calibrated p 2e-6 ✓ | 59.0 EB05 49.8 · IC025 +5.2 3/3 methods agree | Not in label — unassessed | serious n=96 · ♀ 0% (drug 59%) | not reported in cached trials |
| Antineutrophil cytoplasmic antibody positive | 81 | 65.5 52.0–82.6ROR 65.7 · calibrated p 3e-6 ✓ | 57.5 EB05 47.8 · IC025 +5.1 3/3 methods agree | Lab value / disease marker | serious n=81 · ♀ 0% (drug 59%) | not reported in cached trials |
| Dust allergy | 103 | 62.6 51.1–76.8ROR 62.8 · calibrated p 4e-6 ✓ | 55.4 EB05 47.0 · IC025 +5.1 3/3 methods agree | Not in label — unassessed | serious n=103 · ♀ 0% (drug 59%) | not reported in cached trials |
| Rhinocerebral mucormycosis | 36 | 61.5 43.6–86.9ROR 61.6 · calibrated p 6e-6 ✓ | 53.6 EB05 40.5 · IC025 +4.4 3/3 methods agree | Not in label — unassessed | serious n=36 · 100% clinician | not reported in cached trials |
| Neuritis | 158 | 59.9 50.8–70.6ROR 60.2 · calibrated p 5e-6 ✓ | 53.5 EB05 46.8 · IC025 +5.3 3/3 methods agree | Not in label — unassessed | serious n=157 · ♀ 0% (drug 59%) | not reported in cached trials |
| Pulmonary function test abnormal | 145 | 53.6 45.2–63.6ROR 53.8 · calibrated p 1e-5 ✓ | 48.3 EB05 42.1 · IC025 +5.1 3/3 methods agree | Reporting / coding artifact | serious n=144 | not reported in cached trials |
| Female genital tract fistula | 159 | 53.3 45.3–62.7ROR 53.5 · calibrated p 1e-5 ✓ | 48.1 EB05 42.2 · IC025 +5.1 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=159 · ♀ 100% (drug 59%) | not reported in cached trials |
| Abortion incomplete | 154 | 46.5 39.5–54.8ROR 46.7 · calibrated p 2e-5 ✓ | 42.5 EB05 37.2 · IC025 +5.0 3/3 methods agree | Not in label — unassessed | serious n=42 · ♀ 100% (drug 59%) · 100% clinician | not reported in cached trials |
| Bronchiectasis | 534 | 45.6 41.8–49.8ROR 46.2 · calibrated p 2e-5 ✓ | 42.0 EB05 39.1 · IC025 +5.2 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=530 | not reported in cached trials |
| Conjunctivitis allergic | 110 | 42.6 35.1–51.7ROR 42.7 · calibrated p 4e-5 ✓ | 39.2 EB05 33.4 · IC025 +4.8 3/3 methods agree | Labeled (related wording) related wording | serious n=109 · ♀ 0% (drug 59%) | not reported in cached trials |
| Photodermatosis | 32 | 42.5 29.6–60.9ROR 42.5 · calibrated p 6e-5 ✓ | 38.5 EB05 28.5 · IC025 +4.0 3/3 methods agree | Not in label — unassessed | serious n=31 · ♀ 0% (drug 59%) · 100% clinician | not reported in cached trials |
| Chronic sinusitis | 279 | 42.1 37.3–47.6ROR 42.4 · calibrated p 4e-5 ✓ | 38.9 EB05 35.2 · IC025 +5.0 3/3 methods agree | Likely indication confounding term in indications | serious n=275 · ♀ 94% (drug 59%) | not reported in cached trials |
| Respiratory symptom | 203 | 40.9 35.5–47.2ROR 41.1 · calibrated p 5e-5 ✓ | 37.8 EB05 33.7 · IC025 +4.9 3/3 methods agree | Labeled (related wording) related wording | serious n=198 · ♀ 11% (drug 59%) | not reported in cached trials |
| Eosinophilic granulomatosis with polyangiitis | 142 | 39.6 33.4–47.0ROR 39.7 · calibrated p 6e-5 ✓ | 36.7 EB05 31.9 · IC025 +4.8 3/3 methods agree | Not in label — unassessed | serious n=142 · ♀ 0% (drug 59%) | not reported in cached trials |
| Breath sounds abnormal | 325 | 36.9 33.0–41.3ROR 37.2 · calibrated p 8e-5 ✓ | 34.5 EB05 31.4 · IC025 +4.9 3/3 methods agree | Not in label — unassessed | serious n=321 | not reported in cached trials |
| Radiculopathy | 169 | 35.8 30.7–41.9ROR 36.0 · calibrated p 1e-4 ✓ | 33.5 EB05 29.4 · IC025 +4.7 3/3 methods agree | Not in label — unassessed | serious n=168 · ♀ 100% (drug 59%) | not reported in cached trials |
| Rhinitis allergic | 272 | 34.1 30.2–38.6ROR 34.4 · calibrated p 1e-4 ✓ | 32.0 EB05 29.0 · IC025 +4.7 3/3 methods agree | Labeled (related wording) related wording | serious n=271 · ♀ 90% (drug 59%) | not reported in cached trials |
| Bronchial wall thickening | 44 | 33.8 24.9–45.8ROR 33.8 · calibrated p 2e-4 ✓ | 31.4 EB05 24.4 · IC025 +4.1 3/3 methods agree | Likely indication confounding shares a disease stem with the indications wording | serious n=44 · ♀ 100% (drug 59%) | not reported in cached trials |
| Pulmonary cavitation | 52 | 33.5 25.3–44.4ROR 33.6 · calibrated p 2e-4 ✓ | 31.2 EB05 24.7 · IC025 +4.1 3/3 methods agree | Not in label — unassessed | serious n=51 · ♀ 38% (drug 59%) · 100% clinician | not reported in cached trials |
| Forced expiratory volume decreased | 166 | 32.5 27.8–38.0ROR 32.7 · calibrated p 2e-4 ✓ | 30.6 EB05 26.9 · IC025 +4.6 3/3 methods agree | Lab value / disease marker | serious n=165 · ♀ 16% (drug 59%) | not reported in cached trials |
| Malignant melanoma in situ | 70 | 30.8 24.2–39.2ROR 30.8 · calibrated p 3e-4 ✓ | 28.9 EB05 23.7 · IC025 +4.2 3/3 methods agree | Not in label — unassessed | serious n=70 · ♀ 0% (drug 59%) · 100% clinician | not reported in cached trials |
| Proctitis | 155 | 30.6 26.0–36.0ROR 30.7 · calibrated p 3e-4 ✓ | 28.9 EB05 25.3 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious n=155 · ♀ 100% (drug 59%) | not reported in cached trials |
Trial evidence (ClinicalTrials.gov)
✓ Trial adverse-event data found on ClinicalTrials.gov
Largest completed trials with posted results that list Azithromycin as a study intervention. The right-hand column of the signal table shows whether each FAERS term was also recorded in these trials, with a real denominator (0 of 40 signal terms matched).
- NCT04224987 — Azithromycin for Child Survival in Niger: Mortality and Resistance Trial (N=864493, PHASE4; 4 AE terms posted; arms: Azithro 1-11; Azithro 1-59; Placebo)
- NCT02047981 — Mortality Reduction After Oral Azithromycin: Mortality Study (N=190238, PHASE4; 9 AE terms posted; arms: Biannual Mass Oral Azithromycin; Biannual Mass Oral Placebo)
Caveats: trial populations, doses and follow-up differ from the reporting population; AE terms are sponsor-coded and matched here by wording; absence from a trial list means the term was not reported above the sponsor's frequency threshold, not that it cannot occur.
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 |
|---|---|---|---|---|---|---|
| Off label use (used outside approved label) | 4,209 | 2.5 2.5–2.6ROR 2.7 · calibrated p 0.720 | 2.5 EB05 2.5 · IC025 +1.3 3/3 methods agree | Reporting / coding artifact | serious PRR 2.8 | not reported in cached trials |
| Drug ineffective (drug did not work) | 3,984 | 1.6 1.5–1.6ROR 1.7 · calibrated p 0.740 | 1.6 EB05 1.5 · IC025 +0.6 | Reporting / coding artifact | serious PRR 2.7 | not reported in cached trials |
| Dyspnoea (shortness of breath) | 3,290 | 3.1 3.0–3.2ROR 3.2 · calibrated p 0.552 | 3.0 EB05 3.0 · IC025 +1.6 3/3 methods agree | Not in label — unassessed | serious PRR 2.8 | not reported in cached trials |
| Nausea | 2,402 | 1.6 1.5–1.7ROR 1.6 · calibrated p 0.729 | 1.6 EB05 1.5 · IC025 +0.6 | Labeled adverse reaction exact term | serious PRR 1.8 | not reported in cached trials |
| Pain | 2,293 | 2.0 1.9–2.0ROR 2.0 · calibrated p 0.952 | 2.0 EB05 1.9 · IC025 +0.9 | Labeled adverse reaction exact term | serious PRR 2.0 | not reported in cached trials |
| Pneumonia (lung infection) | 2,272 | 3.7 3.6–3.9ROR 3.9 · calibrated p 0.403 | 3.7 EB05 3.6 · IC025 +1.8 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 2.8 | NCT02047981: 1/97,047 (0.0%) on Azithromycin (serious AE) |
| Cough | 2,209 | 4.2 4.0–4.3ROR 4.3 · calibrated p 0.319 | 4.1 EB05 4.0 · IC025 +2.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.4 | not reported in cached trials |
| Diarrhoea (diarrhea) | 1,940 | 1.6 1.5–1.7ROR 1.6 · calibrated p 0.714 | 1.6 EB05 1.5 · IC025 +0.6 | Labeled adverse reaction exact term | serious PRR 1.5 | NCT04224987: 1/104,374 (0.0%) on Azithromycin (serious AE) |
| Fatigue (tiredness) | 1,918 | 1.3 1.2–1.4ROR 1.3 · calibrated p 0.514 | 1.3 EB05 1.2 · IC025 +0.3 | Labeled adverse reaction exact term | serious PRR 1.4 | not reported in cached trials |
| Headache | 1,796 | 1.5 1.4–1.6ROR 1.5 · calibrated p 0.660 | 1.5 EB05 1.4 · IC025 +0.5 | Labeled adverse reaction exact term | serious PRR 1.8 · ♀ 80% (drug 59%) | not reported in cached trials |
| Condition aggravated | 1,760 | 3.1 2.9–3.2ROR 3.2 · calibrated p 0.576 | 3.1 EB05 2.9 · IC025 +1.5 3/3 methods agree | Reporting / coding artifact | serious PRR 3.1 | not reported in cached trials |
| Asthma | 1,671 | 7.9 7.6–8.3ROR 8.2 · calibrated p 0.061 | 7.8 EB05 7.5 · IC025 +2.9 3/3 methods agree | Not in label — unassessed | serious PRR 6.9 | not reported in cached trials |
| Pyrexia (fever) | 1,611 | 2.4 2.3–2.6ROR 2.5 · calibrated p 0.810 | 2.4 EB05 2.3 · IC025 +1.2 3/3 methods agree | Labeled (related wording) related wording | serious PRR 2.1 | not reported in cached trials |
| Vomiting | 1,489 | 1.7 1.6–1.8ROR 1.7 · calibrated p 0.765 | 1.7 EB05 1.6 · IC025 +0.6 | Labeled adverse reaction exact term | serious PRR 1.5 | NCT04224987: 1/104,374 (0.0%) on Azithromycin (serious AE) |
| Anxiety | 1,484 | 2.7 2.6–2.9ROR 2.8 · calibrated p 0.694 | 2.7 EB05 2.6 · IC025 +1.4 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 2.8 | not reported in cached trials |
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.
- Normal labour — n=123, PRR 3,968.3
- Vaginal flatulence — n=154, PRR 537.1
- Congenital hiatus hernia — n=106, PRR 484.2
- Total lung capacity increased — n=118, PRR 400.7
- Heart sounds — n=40, PRR 368.7
- Pulmonary vasculitis — n=169, PRR 247.1
- Asthma-chronic obstructive pulmonary disease overlap syndrome — n=154, PRR 220.8
- Total lung capacity abnormal — n=107, PRR 205.3
- Delivery — n=126, PRR 123.2
- Capillaritis — n=50, PRR 120.0
✓ A hand-written Bradford Hill causality assessment exists for this drug: Azithromycin (macrolides) ↔ QT prolongation / torsades.
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 Azithromycin?
In FDA FAERS, the most frequently co-reported reaction terms for Azithromycin are dyspnoea, nausea, pain, pneumonia, cough, diarrhoea. 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 Azithromycin have an FDA boxed warning?
No. The FDA label retrieved for Azithromycin has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Azithromycin 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 01649d79-4677-4577-a3e4-e054f3f9fc3b, effective 20260820; matched on
openfda.generic_name.exact:"AZITHROMYCIN") - 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, fieldpatient.drug.openfda.generic_name.exact, 1,235 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
AZITHROMYCIN, results-bearing studies sorted by enrollment)
Page generated 2026-10-14. 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.