See also Warning section.
Nausea/vomiting, unwanted/uncontrolled movements, diarrhea, headache, drowsiness, trouble sleeping, increased number of dreams, increased sweating, dry mouth, gas, and abdominal pain may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.
To avoid dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication may develop serious side effects, but with frequent visits to your doctor, this risk can be minimized.
Some people taking tolcapone have fallen asleep suddenly during their usual daily activities (such as talking on the phone, driving). In some cases, sleep occurred without any feelings of drowsiness beforehand. This sleep effect may occur anytime during treatment with tolcapone even if you have used this medication for a long time. If you experience increased sleepiness or fall asleep during the day, do not drive or take part in other possibly dangerous activities until you have discussed this effect with your doctor. Your risk of this sleep effect is increased by using alcohol or other medications that can make you drowsy. See also Precautions section.
Your urine may change color (such as increased yellow color). This effect is harmless.
Tell your doctor right away if you have any serious side effects, including: easy bleeding/bruising, chest pain, fast/irregular heartbeat, fever, mental/mood changes (such as agitation, confusion, hallucinations), unusual strong urges (such as increased gambling, increased sexual urges), muscle pain/soreness/stiffness/weakness, pain/trouble with breathing.
A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.