Donepezil side effects typically last from a few days up to a couple of weeks after starting the medication, but the duration can vary depending on the individual and the specific side effect. Mild side effects such as nausea, vomiting, diarrhea, loss of appetite, dizziness, insomnia, fatigue, and muscle cramps often appear early in treatment and tend to diminish within days to a few weeks as the body adjusts to the drug. However, if these side effects persist beyond a couple of weeks or worsen, it is important to consult a healthcare provider.
More severe side effects, although less common, may require immediate medical attention and can last longer or need specific treatment. These include symptoms like severe stomach pain, bleeding, irregular heartbeat, muscle stiffness, seizures, swelling, or allergic reactions. If such serious side effects occur, the medication may need to be stopped or adjusted under medical supervision.
The timing of donepezil dosing can influence side effects duration and intensity. Many patients start taking donepezil at bedtime to help reduce side effects like dizziness or insomnia. If sleep disturbances or nighttime dizziness occur, switching the dose to the morning may help. Dividing the dose between morning and evening meals has also been reported to reduce continuous nausea.
Individual responses vary widely. Some people experience no side effects at all, while others may have persistent symptoms such as weight loss, muscle cramps, or gastrointestinal upset lasting weeks or longer. In some cases, side effects like vivid dreams or sweating may continue as long as the medication is taken.
If side effects are intolerable or do not resolve, doctors may recommend lowering the dose or discontinuing donepezil. When stopping the medication, side effects usually resolve within days to a few weeks, but this depends on the person’s metabolism and how long they have been on the drug.
In summary, donepezil side effects generally start soon after beginning treatment and often improve within a few days to weeks. Persistent or severe side effects require medical evaluation. Adjusting the timing or dose of donepezil can help manage side effects and improve tolerance.
