What the label lists and what reports show
Felbamate side effects
Felbamate's FDA label: “The most common adverse reactions seen in association with Felbatol ® (felbamate) in adults during monotherapy are anorexia, vomiting, insomnia, nausea, and headache.” FAERS holds 1,751 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 convulsion (124 reports).
- Generic listed
- Boxed warning
Check it at the source: the felbamate FDA label on DailyMed (effective August 15, 2025, Viatris Specialty LLC); 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 FELBATOL?See “What is the most important information I should know about FELBATOL?” FELBATOL may cause serious side effects including: The most common side effects of FELBATOL include: • weight loss • trouble sleeping • sleepiness • vomiting • nausea • headache • changes in the way that food tastes • dizziness • double-vision These are not all the possible side effects of FELBATOL. For more information, ask your healthcare provider or pharmacist. Tell your healthcare provider if you have any side effect that bothers you or that does not go away. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Source: FDA drug label, NDA020189 (Mylan Speciality Lp), as published by Viatris Specialty LLC, effective August 15, 2025 (SPL set 2f522701-397a-11de-8a39-0800200c9a66), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions seen in association with Felbatol ® (felbamate) in adults during monotherapy are anorexia, vomiting, insomnia, nausea, and headache.
A table the label prints in its adverse reactions section without a title; its column headings name the groups compared
This table is printed in the Felbamate label published by Amneal Pharmaceuticals of New York LLC of April 6, 2026; the label quoted above does not print one.
| Body System Event | Felbamate* (N=58) % | Low Dose Valproate** (N=50) % |
|---|---|---|
| Body as a Whole | 6.9 | 4 |
| Fatigue | 3.4 | 0 |
| Weight Decrease | 3.4 | 0 |
| Central Nervous System | 8.6 | 4 |
| Insomnia | 6.9 | 18 |
| Headache | 5.2 | 2 |
| Dermatological | 3.4 | 0 |
| Acne | 3.4 | 0 |
| Digestive | 8.6 | 2 |
| Dyspepsia | 8.6 | 2 |
| Vomiting | 6.9 | 2 |
| Constipation | 5.2 | 0 |
| Diarrhea | 5.2 | 2 |
| Metabolic/Nutritional Hypophosphatemia | 3.4 | 0 |
| Respiratory | 8.6 | 4 |
| Upper Respiratory Tract Infection | 6.9 | 0 |
| Special Senses | 3.4 | 4 |
| Diplopia | 3.4 | 0 |
| Urogenital | 3.4 | 0 |
| Intramenstrual Bleeding | 3.4 | 2 |
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, continuedTo report SUSPECTED ADVERSE REACTIONS, contact Viatris at 1-877-446-3679 (1-877-4-INFO-RX) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. The most common adverse reactions seen in association with Felbatol ® (felbamate) in adults during monotherapy are anorexia, vomiting, insomnia, nausea, and headache. The most common adverse reactions seen in association with Felbatol ® in adults during adjunctive therapy are anorexia, vomiting, insomnia, nausea, dizziness, somnolence, and headache. The most common adverse reactions seen in association with Felbatol ® in children during adjunctive therapy are anorexia, vomiting, insomnia, headache, and somnolence. The dropout rate because of adverse experiences or intercurrent illnesses among adult felbamate patients was 12 percent (120/977). The dropout rate because of adverse experiences or intercurrent illnesses among pediatric felbamate patients was six percent (22/357). In adults, the body systems associated with causing these withdrawals in order of frequency were: digestive (4.3%), psychological (2.2%), whole body (1.7%), neurological (1.5%), and dermatological (1.5%). In children, the body systems associated with causing these withdrawals in order of frequency were: digestive (1.7%), neurological (1.4%), dermatological (1.4%), psychological (1.1%), and whole body (1.0%). …
Source: FDA drug label, NDA020189 (Mylan Speciality Lp), as published by Viatris Specialty LLC, effective August 15, 2025 (SPL set 2f522701-397a-11de-8a39-0800200c9a66), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,751 reports list felbamate among the medicines taken, each a report of something that happened, not proof the medicine caused it; 89 are coded as a death and 542 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 17 reactions below, 8 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?
- Felbamate: 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