What the label lists and what reports show
Donepezil and memantine side effects
Donepezil and memantine's FDA label: “The most common adverse reactions, occurring at a frequency of at least 5% and greater than placebo with memantine hydrochloride extended-release 28 mg/day, were headache, diarrhea, and dizziness.” FAERS holds 608 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 dizziness (58 reports).
- Generic listed
- A presentation discontinued
Check it at the source: the donepezil and memantine FDA label on DailyMed (effective December 17, 2024, Amneal Pharmaceuticals NY 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 memantine and donepezil hydrochlorides extended-release capsules?Memantine and donepezil hydrochlorides extended-release capsules may cause serious side effects, including: muscle problems if you need anesthesia slow heartbeat and fainting. This happens more often in people with heart problems. Call the doctor right away if the patient faints while taking memantine and donepezil hydrochlorides extended-release capsules. more stomach acid. This raises the chance of ulcers and bleeding especially when taking memantine and donepezil hydrochlorides extended-release capsules. The risk is higher for patients who had ulcers, or take aspirin or other NSAIDs. nausea and vomiting difficulty passing urine seizures worsening of lung problems in people with asthma or other lung disease. […]
Source: FDA drug label, Amneal Pharmaceuticals NY LLC, effective December 17, 2024 (SPL set 2335950c-be3b-4248-ad04-e9763aee47d2), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions, occurring at a frequency of at least 5% and greater than placebo with memantine hydrochloride extended-release 28 mg/day, were headache, diarrhea, and dizziness.
Table 2: Adverse reactions with donepezil hydrochloride in patients with severe…
| Body System/Adverse Event | Placebo (n = 392) % | Donepezil hydrochloride 10 mg/day (n = 501) % |
|---|---|---|
| Percent of Patients with any Adverse Event | 73 | 81 |
| Accident | 12 | 13 |
| Infection | 9 | 11 |
| Headache | 3 | 4 |
| Pain | 2 | 3 |
| Back pain | 2 | 3 |
| Fever | 1 | 2 |
| Chest pain | < 1 | 2 |
| Hypertension | 2 | 3 |
| Hemorrhage | 1 | 2 |
| Syncope | 1 | 2 |
| Diarrhea | 4 | 10 |
| Vomiting | 4 | 8 |
| Anorexia | 4 | 8 |
| Nausea | 2 | 6 |
| Ecchymosis | 2 | 5 |
| Increased creatine phosphokinase | 1 | 3 |
| Dehydration | 1 | 2 |
| Hyperlipemia | < 1 | 2 |
| Insomnia | 4 | 5 |
| Hostility | 2 | 3 |
| Nervousness | 2 | 3 |
| Hallucinations | 1 | 3 |
| Somnolence | 1 | 2 |
| Dizziness | 1 | 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, continuedThe following serious adverse reactions are discussed below and elsewhere in the labeling. Cardiovascular Conditions [see Warnings and Precautions (5.2) ] Peptic Ulcer Disease and Gastrointestinal Bleeding [see Warnings and Precautions (5.3) ] Nausea and Vomiting [see Warnings and Precautions (5.4) ] Genitourinary Conditions [see Warnings and Precautions (5.5) ] Seizures [see Warnings and Precautions (5.6) ] Pulmonary Conditions [see Warnings and Precautions (5.7) ] The most common adverse reactions, occurring at a frequency of at least 5% and greater than placebo with memantine hydrochloride extended-release 28 mg/day, were headache, diarrhea, and dizziness. (6.1) The most common adverse reactions occurring at a frequency of at least 5% in patients receiving donepezil and at twice or more the placebo rate, include diarrhea, anorexia, vomiting, nausea, and ecchymosis. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Amneal Pharmaceuticals at 1-877-835-5472 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Source: FDA drug label, Amneal Pharmaceuticals NY LLC, effective December 17, 2024 (SPL set 2335950c-be3b-4248-ad04-e9763aee47d2), via openFDA; the full label on DailyMed
What do FAERS reports show?
608 reports list donepezil and memantine among the medicines taken, each a report of something that happened, not proof the medicine caused it; 72 are coded as a death and 117 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 18 reactions below, 9 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?
- Donepezil and memantine: 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