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 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.

Serious side effects of Comtan

Along with its needed effects, entacapone (the active ingredient contained in Comtan) 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:

More common side effects

• absence of or decrease in body movements
• hyperactivity
• increase in body movements
• seeing, hearing, or feeling things that are not there
• twisting
• twitching
• uncontrolled repetitive movements of the tongue, lips, face, arms, or legs

Less common side effects

• cough or hoarseness
• fever or chills
• lower back or side pain
• painful or difficult urination

Rare side effects

• confusion
• muscle cramps
• pain
• shortness of breath
• stiffness
• unusual tiredness or weakness

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:

More common side effects

• abdominal or stomach pain
• constipation
• diarrhea
• dizziness
• nausea

Less common side effects

• acid or sour stomach
• anxiety
• belching
• bruising
• burning feeling in the chest or stomach
• difficult or labored breathing
• dry mouth
• heartburn
• indigestion
• irritability
• loss of strength or energy
• muscle pain or weakness
• passing gas
• restlessness
• sleepiness or unusual drowsiness
• small, red spots on the skin
• stomach discomfort, upset, or tenderness
• sweating increased
• tightness in the chest
• tremor
• trouble sleeping
• unusual or unpleasant (after) taste
• unusual weak feeling

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]

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