Comtan Side Effects

Generic name: entacapone

Medically reviewed by Drugs.com. Last updated on May 14, 2024.

Note: This document provides detailed information about Comtan.

Applies to entacapone: oral tablet Side Effects associated with entacapone. Some dosage forms listed on this page may not apply specifically to the brand name Comtan.

Applies to entacapone: oral tablet.

Precautions

It is important that your doctor check your progress at regular visits to make sure that this medicine is working properly and to check for unwanted effects.

You should not use certain MAO inhibitors (such as phenelzine, tranylcypromine) while using this medicine.

Do not stop taking entacapone (the active ingredient contained in Comtan) without first checking with your doctor. Your doctor may want you to gradually reduce the amount you are taking before stopping completely.

This medicine may make you dizzy or drowsy. It may even cause you to fall asleep without warning while you drive, talk, or eat. Do not drive or do anything that could be dangerous until you know how this medicine affects you.

This medicine will add to the effects of other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds, sedatives, tranquilizers, or sleeping medicine, prescription pain medicine or narcotics, medicine for seizures or barbiturates, muscle relaxants, or anesthetics, including some dental anesthetics. Check with your medical doctor or dentist before taking any of the above while you are taking this medicine.

It is possible that you may become nauseous, especially when you are first starting your medicine.

Dizziness, lightheadedness, or fainting may occur, especially when you get up from a lying or sitting position. Getting up slowly may help. If you should have this problem, check with your doctor.

If you develop any unusual or strange thoughts and behavior while receiving this medicine, be sure to discuss it with your doctor. Other changes might be confusion, worsening of depression, visual hallucinations (seeing things that are not there), suicidal thoughts, and unusual excitement, nervousness, or irritability.

Some people who have used this medicine had unusual changes in their behavior. Talk with your doctor right away if you start having problems with gambling or an increased interest in sex while using this medicine.

This medicine may cause diarrhea, and in some cases it can be severe. It can occur months after starting this medicine. Do not take any medicine to treat diarrhea without first checking with your doctor. Diarrhea medicines may make the diarrhea worse or make it last longer. If you have any questions about this or if mild diarrhea continues or gets worse, check with your doctor.

Check with your doctor right away if you have dark-colored urine, fever, muscle cramps or spasms, muscle pain or stiffness, or unusual tiredness or weakness. These may be symptoms of a condition called rhabdomyolysis.

Check with your doctor right away if you are having convulsions (seizures), difficulty with breathing, a fast heartbeat, a high fever, high or low blood pressure, increased sweating, loss of bladder control, severe muscle stiffness, unusually pale skin, or tiredness. These could be symptoms of a serious condition called neuroleptic malignant syndrome (NMS).

It is important that your doctor check your skin regularly for signs of a skin cancer called melanoma. If you notice any unusual red, brown, or black spots on your skin, talk to your doctor right away.

This medicine may cause your urine to turn brownish orange. This is normal and nothing to worry about.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Serious side effects of Comtan

Along with its needed effects, entacapone may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking entacapone:

Other side effects of Comtan

Some side effects of entacapone may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

For healthcare professionals

Applies to entacapone: oral tablet.

General adverse events

The most commonly reported adverse reactions included dyskinesia, urine discoloration, diarrhea, nausea, hyperkinesia, abdominal pain, vomiting, and dry mouth.^[Ref]

Gastrointestinal

• Very common (10% or more): Nausea (up to 14%), diarrhea (up to 11%)
• Common (1% to 10%): Abdominal pain, constipation, vomiting, dry mouth, dyspepsia, flatulence, gastritis, gastrointestinal disorders
• Very rare (less than 0.01%): Anorexia
• Postmarketing reports: Colitis^[Ref]

In clinical trials, diarrhea occurred in approximately 10% of patients. It was generally mild to moderate, but in 1.3% of people it was severe. Upon discontinuation, diarrhea generally resolved. There have been postmarketing reports of drug-induced microscopic colitis, primarily lymphocytic colitis.^[Ref]

Genitourinary

• Very common (10% or more): Urine discoloration (10%)^[Ref]

Nervous system

• Very common (10% or more): Dyskinesia (up to 27%), hyperkinesia (10%)
• Common (1% to 10%): Hypokinesia, dizziness, somnolence, taste perversion, aggravated parkinsonism, dystonia, headache, tremor
• Frequency not reported: Falling asleep during activities of daily living
• Postmarketing reports: Neuroleptic malignant syndrome^[Ref]

There were no cases of neuroleptic malignant syndrome during clinical trials. Since market introduction, there have been isolated cases, especially following abrupt reduction or discontinuation of this drug and other concomitant dopaminergic drugs.^[Ref]

Respiratory

• Common (1% to 10%): Dyspnea
• Frequency not reported: Pulmonary fibrosis^[Ref]

Dermatologic

• Common (1% to 10%): Increased sweating
• Rare (less than 0.1%): Erythematous, maculopapular rash
• Very rare (less than 0.01%): Urticaria
• Frequency not reported: Skin hair, beard, and nail discolorations^[Ref]

Musculoskeletal

• Common (1% to 10%): Back pain, falls, leg cramps
• Postmarketing reports: Rhabdomyolysis^[Ref]

Isolated cases of rhabdomyolysis have occurred in patients treated with this drug. The complicated nature of these cases makes it difficult to determine the role this drug may have had. Rhabdomyolysis has been reported secondary to severe dyskinesias or neuroleptic malignant syndrome (NMS) in patients with Parkinson's disease.^[Ref]

Psychiatric

• Common (1% to 10%): Anxiety, insomnia, hallucinations, confusion, paranoia
• Uncommon (0.1% to 1%): Agitation
• Frequency not reported: Impulse control disorders including pathological gambling, increased libido, hypersexuality, compulsive spending or buying, binge eating and compulsive eating^[Ref]

Hematologic

• Common (1% to 10%): Purpura, decreased hemoglobin^[Ref]

A clinically significant decrease in hemoglobin has been observed in 1.8% of patients. The underlying mechanism may involve decreased absorption of iron from the gastrointestinal tract.^[Ref]

Other

• Common (1% to 10%): Fatigue, asthenia, pain, vertigo^[Ref]

Cardiovascular

• Common (1% to 10%): Ischemic heart disease events other than myocardial infarction (e.g., angina pectoris, postural hypotension
• Uncommon (0.1% to 1%): Myocardial infarction^[Ref]

The incidence of myocardial infarction and other ischemic heart disease events was 0.43% and 1.54%, respectively, in an analysis of 13 double-blind studies involving 2082 patients.^[Ref]

Hepatic

• Rare (less than 0.1%): Abnormal liver function tests
• Postmarketing reports: Hepatitis with mainly cholestatic features^[Ref]

See also:

Frequently asked questions

• Is Ongentys better than Comtan?

Further information

Comtan side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer