Drug · FAERS side-effect profile with label screen
Baclofen side effects: what 3,087 FDA adverse event reports show
Drug class
gamma-Aminobutyric Acid-ergic Agonist
FDA label (Established Pharmacologic Class)
Who reports
3,087 reports · 50% serious · 121 with death outcome · 44% female
openFDA FAERS counts, all years, deduplication not applied
Used for
Baclofen tablets are useful for the alleviation of signs and symptoms of spasticity resulting from multiple sclerosis, particularly for the relief of flexor spasms and concomitant pain, clonus, and muscular rigidity. Patients should have reversible spasticity so that baclofen treatment will aid in restoring residual function.
FDA label, Indications and Usage
What it is
DESCRIPTION Baclofen, USP is a muscle relaxant and antispastic.
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 3Labeled (related wording) 2Likely indication confounding 3Reporting / coding artifact 14Not 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.
- 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. 28 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.
Show:
| Reaction | Reports | PRR 95% CI · ROR · χ²/p | EBGM EB05 · IC025 | Label screen | Serious-only & strata | Trial cross-check |
|---|---|---|---|---|---|---|
| Muscle spasticity | 764 | 446.2 418.5–475.8ROR 592.6 · χ² 317,950 / p <1e-300 | 414.0 EB05 390.0 · IC025 +8.2 3/3 methods agree | Likely indication confounding term in indications | serious PRR 297.7 | no trial data cached |
| Device failure | 154 | 69.7 59.7–81.3ROR 73.3 · χ² 10,253 / p <1e-300 | 68.4 EB05 59.8 · IC025 +5.6 3/3 methods agree | Reporting / coding artifact | serious PRR 157.5 · 70% consumer | no trial data cached |
| Withdrawal syndrome | 410 | 66.6 60.8–72.9ROR 76.7 · χ² 26,220 / p <1e-300 | 65.8 EB05 60.6 · IC025 +5.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 51.9 | no trial data cached |
| Hypotonia | 79 | 53.9 43.3–67.1ROR 55.3 · χ² 4,021 / p <1e-300 | 52.9 EB05 43.8 · IC025 +5.0 3/3 methods agree | Not in label — unassessed | serious PRR 47.7 | no trial data cached |
| Muscle tightness | 81 | 34.2 27.6–42.4ROR 35.1 · χ² 2,564 / p <1e-300 | 33.8 EB05 28.0 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious PRR 32.4 | no trial data cached |
| Device occlusion | 65 | 31.9 25.1–40.6ROR 32.6 · χ² 1,906 / p <1e-300 | 31.5 EB05 25.6 · IC025 +4.3 3/3 methods agree | Reporting / coding artifact | serious n=32 | no trial data cached |
| Device issue | 376 | 29.4 26.7–32.3ROR 33.3 · χ² 10,283 / p <1e-300 | 29.2 EB05 26.8 · IC025 +4.6 3/3 methods agree | Reporting / coding artifact | serious PRR 65.6 | no trial data cached |
| Drug withdrawal syndrome | 272 | 20.9 18.6–23.4ROR 22.8 · χ² 5,137 / p <1e-300 | 20.8 EB05 18.8 · IC025 +4.1 3/3 methods agree | Labeled (related wording) related wording | serious PRR 23.1 | no trial data cached |
| Device malfunction | 151 | 15.3 13.1–17.9ROR 16.0 · χ² 2,005 / p <1e-300 | 15.2 EB05 13.3 · IC025 +3.6 3/3 methods agree | Reporting / coding artifact | serious PRR 32.6 | no trial data cached |
| Muscle rigidity | 25 | 14.2 9.6–21.0ROR 14.3 · χ² 294 / p 3e-66 | 13.8 EB05 9.5 · IC025 +2.8 3/3 methods agree | Likely indication confounding term in indications; also in warnings | serious PRR 10.2 | no trial data cached |
| Mental status changes | 51 | 12.5 9.5–16.4ROR 12.7 · χ² 527 / p 6e-117 | 12.2 EB05 9.5 · IC025 +3.0 3/3 methods agree | Not in label — unassessed | serious PRR 13.6 | no trial data cached |
| Device dislocation | 77 | 12.1 9.7–15.1ROR 12.4 · χ² 771 / p 5e-170 | 11.9 EB05 9.7 · IC025 +3.1 3/3 methods agree | Reporting / coding artifact | serious PRR 14.0 · ♀ 75% (drug 44%) | no trial data cached |
| Device breakage | 63 | 10.9 8.5–13.9ROR 11.1 · χ² 557 / p 2e-123 | 10.6 EB05 8.5 · IC025 +2.9 3/3 methods agree | Reporting / coding artifact | serious PRR 12.4 | no trial data cached |
| Unresponsive to stimuli | 32 | 8.5 6.0–11.9ROR 8.5 · χ² 203 / p 2e-46 | 7.8 EB05 5.7 · IC025 +2.3 3/3 methods agree | Not in label — unassessed | serious PRR 9.5 | no trial data cached |
| Complication associated with device | 16 | 8.2 5.0–13.4ROR 8.3 · χ² 94 / p 1e-22 | 7.0 EB05 4.4 · IC025 +1.9 3/3 methods agree | Not in label — unassessed | serious PRR 12.5 | no trial data cached |
| Infection | 163 | 7.7 6.6–8.9ROR 8.1 · χ² 947 / p 3e-208 | 7.6 EB05 6.6 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 6.6 | no trial data cached |
| Underdose | 79 | 7.4 5.9–9.1ROR 7.5 · χ² 428 / p 2e-95 | 7.1 EB05 5.9 · IC025 +2.4 3/3 methods agree | Reporting / coding artifact | serious PRR 16.2 | no trial data cached |
| Staphylococcal infection | 34 | 7.0 5.0–9.8ROR 7.0 · χ² 168 / p 8e-39 | 6.5 EB05 4.8 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 8.5 | no trial data cached |
| Drug effect decreased | 51 | 6.3 4.8–8.3ROR 6.4 · χ² 225 / p 4e-51 | 6.0 EB05 4.8 · IC025 +2.1 3/3 methods agree | Reporting / coding artifact | serious PRR 13.7 · 79% consumer | no trial data cached |
| Aspiration | 10 | 6.3 3.4–11.7ROR 6.3 · χ² 39 / p 2e-10 | 5.0 EB05 2.9 · IC025 +1.2 3/3 methods agree | Not in label — unassessed | serious PRR 7.4 | no trial data cached |
| Agitation | 67 | 6.2 4.9–7.8ROR 6.3 · χ² 287 / p 1e-64 | 5.9 EB05 4.8 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 7.8 | no trial data cached |
| Device leakage | 38 | 6.1 4.4–8.4ROR 6.2 · χ² 157 / p 2e-36 | 5.7 EB05 4.3 · IC025 +2.0 3/3 methods agree | Reporting / coding artifact | serious n=17 | no trial data cached |
| Therapy non-responder | 40 | 6.1 4.5–8.3ROR 6.2 · χ² 166 / p 3e-38 | 5.7 EB05 4.4 · IC025 +2.0 3/3 methods agree | Reporting / coding artifact | serious PRR 7.1 | no trial data cached |
| No therapeutic response | 11 | 6.0 3.3–10.9ROR 6.1 · χ² 41 / p 6e-11 | 4.9 EB05 2.9 · IC025 +1.3 3/3 methods agree | Reporting / coding artifact | serious PRR 8.7 | no trial data cached |
| Irritability | 52 | 5.9 4.5–7.7ROR 6.0 · χ² 206 / p 6e-47 | 5.6 EB05 4.4 · IC025 +2.0 3/3 methods agree | Not in label — unassessed | serious PRR 7.3 | no trial data cached |
| Musculoskeletal stiffness | 73 | 5.7 4.5–7.1ROR 5.8 · χ² 276 / p 2e-62 | 5.5 EB05 4.5 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 4.9 | no trial data cached |
| Dystonia | 16 | 5.6 3.4–9.1ROR 5.6 · χ² 56 / p 4e-14 | 4.9 EB05 3.2 · IC025 +1.5 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 4.4 | no trial data cached |
| Muscle spasms | 146 | 5.4 4.6–6.3ROR 5.6 · χ² 524 / p 3e-116 | 5.3 EB05 4.6 · IC025 +2.1 3/3 methods agree | Likely indication confounding term in indications | serious PRR 6.6 | no trial data cached |
| Overdose | 170 | 5.3 4.6–6.2ROR 5.6 · χ² 600 / p 8e-133 | 5.3 EB05 4.6 · IC025 +2.1 3/3 methods agree | Reporting / coding artifact | serious PRR 6.1 | no trial data cached |
| Muscle twitching | 17 | 5.0 3.1–8.0ROR 5.0 · χ² 50 / p 6e-13 | 4.4 EB05 2.9 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 4.2 | no trial data cached |
| Device related infection | 11 | 4.8 2.7–8.7ROR 4.9 · χ² 30 / p 2e-8 | 4.1 EB05 2.5 · IC025 +1.0 3/3 methods agree | Reporting / coding artifact | serious PRR 5.7 | no trial data cached |
| Sedation | 17 | 4.4 2.8–7.1ROR 4.5 · χ² 42 / p 5e-11 | 4.0 EB05 2.7 · IC025 +1.2 3/3 methods agree | Not in label — unassessed | serious PRR 6.1 | no trial data cached |
| Depressed level of consciousness | 25 | 4.3 2.9–6.4ROR 4.3 · χ² 60 / p 4e-15 | 4.0 EB05 2.9 · IC025 +1.3 3/3 methods agree | Not in label — unassessed | serious PRR 5.0 | no trial data cached |
| Lethargy | 36 | 4.3 3.1–5.9ROR 4.3 · χ² 87 / p 7e-21 | 4.0 EB05 3.1 · IC025 +1.5 3/3 methods agree | Not in label — unassessed | serious PRR 5.4 | no trial data cached |
| Osteomyelitis | 10 | 3.8 2.0–7.0ROR 3.8 · χ² 18 / p 1e-5 | 3.3 EB05 1.9 · IC025 +0.7 | Not in label — unassessed | serious PRR 4.4 | no trial data cached |
| Discomfort | 33 | 3.7 2.6–5.2ROR 3.7 · χ² 62 / p 1e-15 | 3.5 EB05 2.6 · IC025 +1.2 3/3 methods agree | Not in label — unassessed | serious PRR 4.7 | no trial data cached |
| Dyskinesia (involuntary movements) | 22 | 3.7 2.4–5.6ROR 3.7 · χ² 40 / p 1e-10 | 3.5 EB05 2.4 · IC025 +1.1 3/3 methods agree | Not in label — unassessed | serious PRR 3.9 | no trial data cached |
| Urinary retention | 18 | 3.7 2.3–5.8ROR 3.7 · χ² 32 / p 6e-9 | 3.4 EB05 2.3 · IC025 +1.0 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.9 | no trial data cached |
| Seizure | 53 | 3.1 2.4–4.1ROR 3.2 · χ² 75 / p 2e-18 | 3.1 EB05 2.4 · IC025 +1.2 3/3 methods agree | Labeled adverse reaction exact term | serious PRR 3.8 | no trial data cached |
| Therapeutic response decreased | 26 | 2.9 2.0–4.3ROR 2.9 · χ² 31 / p 1e-8 | 2.8 EB05 2.0 · IC025 +0.8 3/3 methods agree | Reporting / coding artifact | serious PRR 3.9 | 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 |
|---|---|---|---|---|---|---|
| Muscle spasticity | 764 | 446.2 418.5–475.8ROR 592.6 · χ² 317,950 / p <1e-300 | 414.0 EB05 390.0 · IC025 +8.2 3/3 methods agree | Likely indication confounding term in indications | serious PRR 297.7 | no trial data cached |
| Withdrawal syndrome | 410 | 66.6 60.8–72.9ROR 76.7 · χ² 26,220 / p <1e-300 | 65.8 EB05 60.6 · IC025 +5.8 3/3 methods agree | Labeled (related wording) related wording | serious PRR 51.9 | no trial data cached |
| Device issue | 376 | 29.4 26.7–32.3ROR 33.3 · χ² 10,283 / p <1e-300 | 29.2 EB05 26.8 · IC025 +4.6 3/3 methods agree | Reporting / coding artifact | serious PRR 65.6 | no trial data cached |
| Drug withdrawal syndrome | 272 | 20.9 18.6–23.4ROR 22.8 · χ² 5,137 / p <1e-300 | 20.8 EB05 18.8 · IC025 +4.1 3/3 methods agree | Labeled (related wording) related wording | serious PRR 23.1 | no trial data cached |
| Overdose | 170 | 5.3 4.6–6.2ROR 5.6 · χ² 600 / p 8e-133 | 5.3 EB05 4.6 · IC025 +2.1 3/3 methods agree | Reporting / coding artifact | serious PRR 6.1 | no trial data cached |
| Infection | 163 | 7.7 6.6–8.9ROR 8.1 · χ² 947 / p 3e-208 | 7.6 EB05 6.6 · IC025 +2.7 3/3 methods agree | Not in label — unassessed | serious PRR 6.6 | no trial data cached |
| Device failure | 154 | 69.7 59.7–81.3ROR 73.3 · χ² 10,253 / p <1e-300 | 68.4 EB05 59.8 · IC025 +5.6 3/3 methods agree | Reporting / coding artifact | serious PRR 157.5 · 70% consumer | no trial data cached |
| Device malfunction | 151 | 15.3 13.1–17.9ROR 16.0 · χ² 2,005 / p <1e-300 | 15.2 EB05 13.3 · IC025 +3.6 3/3 methods agree | Reporting / coding artifact | serious PRR 32.6 | no trial data cached |
| Muscle spasms | 146 | 5.4 4.6–6.3ROR 5.6 · χ² 524 / p 3e-116 | 5.3 EB05 4.6 · IC025 +2.1 3/3 methods agree | Likely indication confounding term in indications | serious PRR 6.6 | no trial data cached |
| Muscle tightness | 81 | 34.2 27.6–42.4ROR 35.1 · χ² 2,564 / p <1e-300 | 33.8 EB05 28.0 · IC025 +4.5 3/3 methods agree | Not in label — unassessed | serious PRR 32.4 | no trial data cached |
| Underdose | 79 | 7.4 5.9–9.1ROR 7.5 · χ² 428 / p 2e-95 | 7.1 EB05 5.9 · IC025 +2.4 3/3 methods agree | Reporting / coding artifact | serious PRR 16.2 | no trial data cached |
| Hypotonia | 79 | 53.9 43.3–67.1ROR 55.3 · χ² 4,021 / p <1e-300 | 52.9 EB05 43.8 · IC025 +5.0 3/3 methods agree | Not in label — unassessed | serious PRR 47.7 | no trial data cached |
| Device dislocation | 77 | 12.1 9.7–15.1ROR 12.4 · χ² 771 / p 5e-170 | 11.9 EB05 9.7 · IC025 +3.1 3/3 methods agree | Reporting / coding artifact | serious PRR 14.0 · ♀ 75% (drug 44%) | no trial data cached |
| Musculoskeletal stiffness | 73 | 5.7 4.5–7.1ROR 5.8 · χ² 276 / p 2e-62 | 5.5 EB05 4.5 · IC025 +2.1 3/3 methods agree | Not in label — unassessed | serious PRR 4.9 | no trial data cached |
| Agitation | 67 | 6.2 4.9–7.8ROR 6.3 · χ² 287 / p 1e-64 | 5.9 EB05 4.8 · IC025 +2.2 3/3 methods agree | Not in label — unassessed | serious PRR 7.8 | 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.
- Hypotonia — n=79, PRR 53.9
- Muscle tightness — n=81, PRR 34.2
- Mental status changes — n=51, PRR 12.5
- Unresponsive to stimuli — n=32, PRR 8.5
- Infection — n=163, PRR 7.7
- Staphylococcal infection — n=34, PRR 7.0
- Agitation — n=67, PRR 6.2
- Irritability — n=52, PRR 5.9
- Musculoskeletal stiffness — n=73, PRR 5.7
- Depressed level of consciousness — n=25, PRR 4.3
✓ A hand-written Bradford Hill causality assessment exists for this drug: Baclofen ↔ Somnolence.
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 Baclofen?
In FDA FAERS, the most frequently co-reported reaction terms for Baclofen are muscle spasticity, withdrawal syndrome, drug withdrawal syndrome, infection, muscle spasms, muscle tightness. 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 Baclofen have an FDA boxed warning?
No. The FDA label retrieved for Baclofen has no boxed warning; see the label's Warnings and Precautions for the recognised risks.
Do FAERS signals prove that Baclofen 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 06bcfb08-2ada-f803-e063-6394a90a826b, effective 20251226; matched on
openfda.generic_name.exact:"BACLOFEN") - 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, 68 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.