Common Side Effects of Entacapone
Entacapone has been studied thoroughly in clinical trials. In these studies, the side effects that occurred in a group of people taking entacapone (along with
carbidopa-levodopa) were documented and compared to side effects that occurred in another group of people taking just
carbidopa-levodopa (without entacapone). This way, it was possible to see what side effects occurred, how often they appeared, and how they compared to the group taking just carbidopa-levodopa.
In these studies, the most common side effects of entacapone plus carbidopa-levodopa included:
- Involuntary body movements (dyskinesia) -- in up to 25 percent of people
- Nausea -- up to 14 percent
- Diarrhea -- up to 10 percent
- Urine discoloration -- up to 10 percent
- Excessive muscle movements (hyperkinesia) -- up to 10 percent
- Slow or diminished muscle movements (hypokinesia) -- up to 9 percent
- Dizziness -- up to 8 percent
- Abdominal pain (stomach pain) -- up to 8 percent.
Other common side effects (occurring in 1 to 6 percent of people) included:
- Increased sweating
- Back pain
- Taste changes
- Constipation
- Vomiting
- Dry mouth
- Indigestion or heartburn
- Gas
- Red or purple bruise-like spots (known as purpura)
- Fatigue
- Weakness
- Bacterial infection.
It is important to point out that many of these side effects are caused, in large part, by the carbidopa-levodopa, not by entacapone. However, this is of little importance, since entacapone is always used in combination with carbidopa-levodopa (it has no activity against
Parkinson's disease when used by itself). Also, because entacapone increases the level of levodopa in the blood, it may increase the risk or worsen the
side effects of carbidopa-levodopa.