What the label lists and what reports show
Baclofen side effects
Baclofen's FDA label: “The most common is transient drowsiness (10 to 63%).” FAERS holds 88,351 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is fatigue (6,295 reports).
- Generic listed
Check it at the source: the baclofen FDA label on DailyMed (effective August 12, 2024, Zydus Lifesciences Limited); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of LYVISPAH?LYVISPAH can cause serious side effects, including: risk of symptoms from stopping LYVISPAH . Stopping LYVISPAH suddenly can cause severe muscle problems, organ failure, and death. Early symptoms include increased muscle stiffness, itching, and tingling in hands and feet. Other symptoms include seeing or hearing things that are not there (hallucinations), seizures, high fever, and confusion (altered mental status). Your healthcare provider will slowly reduce your dose of LYVISPAH when stopping treatment. withdrawal symptoms in infants (Neonatal Withdrawal Symptoms). LYVISPAH can cause withdrawal symptoms in infants after delivery. Symptoms of withdrawal of LYVISPAH in infants include stiffness in arms or legs, tremor, jitteriness, and seizure. drowsiness and sedation. If you take certain medicines or drink alcohol while taking LYVISPAH, your drowsiness may get worse. […]
Source: FDA drug label (LYVISPAH), Amneal Pharmaceuticals LLC, effective April 23, 2023 (SPL set f8992a56-9010-4c4b-84d5-ddcc3e2c3317), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common is transient drowsiness (10 to 63%).
INCIDENCE OF MOST FREQUENT (≥1%) ADVERSE EVENTS IN PATIENTS WITH SPASTICITY OF SPINAL ORIGIN IN PROSPECTIVELY MONITORED CLINICAL TRIALS
This table is printed in the Lioresal (baclofen) label published by Amneal Pharmaceuticals LLC of December 9, 2022; the label quoted above does not print one.
| Reaction | N = 576 Screening * Percent | N = 474 Titration † Percent | N = 430 Maintenance ‡ Percent |
|---|---|---|---|
| Hypotonia | 5.4 | 13.5 | 25.3 |
| Somnolence | 5.7 | 5.9 | 20.9 |
| Dizziness | 1.7 | 1.9 | 7.9 |
| Paresthesia | 2.4 | 2.1 | 6.7 |
| Nausea and Vomiting | 1.6 | 2.3 | 5.6 |
| Headache | 1.6 | 2.5 | 5.1 |
| Constipation | 0.2 | 1.5 | 5.1 |
| Convulsion | 0.5 | 1.3 | 4.7 |
| Urinary Retention | 0.7 | 1.7 | 1.9 |
| Dry Mouth | 0.2 | 0.4 | 3.3 |
| Accidental Injury | 0.0 | 0.2 | 3.5 |
| Asthenia | 0.7 | 1.3 | 1.4 |
| Confusion | 0.5 | 0.6 | 2.3 |
| Death | 0.2 | 0.4 | 3.0 |
| Pain | 0.0 | 0.6 | 3.0 |
| Speech Disorder | 0.0 | 0.2 | 3.5 |
| Hypotension | 1.0 | 0.2 | 1.9 |
| Ambylopia | 0.5 | 0.2 | 2.3 |
| Diarrhea | 0.0 | 0.8 | 2.3 |
| Hypoventilation | 0.2 | 0.8 | 2.1 |
| Coma | 0.0 | 1.5 | 0.9 |
| Impotence | 0.2 | 0.4 | 1.6 |
| Peripheral Edema | 0.0 | 0.0 | 2.3 |
| Urinary Incontinence | 0.0 | 0.8 | 1.4 |
| Insomnia | 0.0 | 0.4 | 1.6 |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe most common is transient drowsiness (10 to 63%). In one controlled study of 175 patients, transient drowsiness was observed in 63% of those receiving baclofen compared to 36% of those in the placebo group. Other common adverse reactions are dizziness (5 to 15%), weakness (5 to 15%) and fatigue (2 to 4%). Others reported: Neuropsychiatric: Confusion (1 to 11%), headache (4 to 8%), insomnia (2 to 7%); and, rarely, euphoria, excitement, depression, hallucinations, paresthesia, muscle pain, tinnitus, slurred speech, coordination disorder, tremor, rigidity, dystonia, ataxia, blurred vision, nystagmus, strabismus, miosis, mydriasis, diplopia, dysarthria, epileptic seizure. Cardiovascular: Hypotension (0 to 9%). Rare instances of dyspnea, palpitation, chest pain, syncope. Gastrointestinal: Nausea (4 to 12%), constipation (2 to 6%); and rarely, dry mouth, anorexia, taste disorder, abdominal pain, vomiting, diarrhea, and positive test for occult blood in stool. Genitourinary: Urinary frequency (2 to 6%); and rarely, enuresis, urinary retention, dysuria, impotence, inability to ejaculate, nocturia, hematuria. Other: Instances of rash, pruritus, ankle edema, excessive perspiration, weight gain, nasal congestion. Some of the CNS and genitourinary symptoms may be related to the underlying disease rather than to drug therapy. …
Source: FDA drug label, Zydus Lifesciences Limited, effective August 12, 2024 (SPL set bb5c6faa-2933-44d1-8706-8302150be734), via openFDA; the full label on DailyMed
What do FAERS reports show?
88,351 reports list baclofen among the medicines taken, each a report of something that happened, not proof the medicine caused it; 6,567 are coded as a death and 28,758 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 22 reactions below, 10 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Baclofen: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions