Pill Identifier App

Comtan Side Effects

Generic Name: entacapone

Note: This page contains information about the side effects of entacapone. Some of the dosage forms included on this document may not apply to the brand name Comtan.

Not all side effects for Comtan may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to entacapone: oral tablet

In addition to its needed effects, some unwanted effects may be caused by entacapone (the active ingredient contained in Comtan). In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when taking entacapone:

More common
  • 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
  • Cough or hoarseness
  • fever or chills
  • lower back or side pain
  • painful or difficult urination
  • Confusion
  • muscle cramps
  • pain
  • shortness of breath
  • stiffness
  • unusual tiredness or weakness

Some of the side effects that can occur with entacapone may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common
  • Abdominal or stomach pain
  • constipation
  • diarrhea
  • dizziness
  • nausea
Less common
  • 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

Nervous system

Nervous system side effects have included dyskinesia (25%), hyperkinesia (10%), hypokinesia (9%), and dizziness (8%).[Ref]


Gastrointestinal side effects have included nausea (14%), diarrhea (10%), abdominal pain (8%), constipation (6%), vomiting (4%), dry mouth (3%), dyspepsia (2%), flatulence (2%), and gastritis (1%).[Ref]


Genitourinary side effects have included urinary discoloration (10%).[Ref]


General side effects have included fatigue (6%), back pain (4%), and asthenia (2%).[Ref]


Respiratory side effects have included dyspnea (3%).[Ref]


A 50-year-old male with an 8-year history of dilatative cardiomyopathy and a 5-year history of Parkinson's disease experienced a bullous skin eruption coincident with entacapone (the active ingredient contained in Comtan) therapy. The patient was prescribed entacapone 200 mg five times a day due to progression of his extrapyramidal symptoms. After 15 days, bullous lesions were observed initially on the left leg and suddenly affected most of the body surface. During the first day of hospitalization, a dramatic deterioration of general conditions was noted with development of hyperpyrexia (39 degrees Celsius), severe hypotension (75/50 mmHg), pulmonary congestion, and acute renal failure with marked oliguria. Entacapone was discontinued and treatment with intramuscular cefazolin, intravenous corticosteroid, and cardio-respiratory therapy was initiated. General conditions improved after a few days, and the skin lesions completely disappeared after 10 days.[Ref]

Dermatologic side effects have included increased sweating (2%). At least one case of bullous skin eruption has been reported.[Ref]


Musculoskeletal side effects have included back pain (2%).[Ref]


Psychiatric side effects have included anxiety (2%), somnolence (2%), and agitation (1%).[Ref]


Hematologic side effects have included purpura (2%).[Ref]


Other side effects have included taste perversion (1%).[Ref]


Immunologic side effects have included bacterial infection (1%).[Ref]


1. "Product Information. Comtan (entacapone)" Novartis Pharmaceuticals, East Hanover, NJ.

2. Foti C, Cassano N, De Mari M, Sorino M, Vena GA "Bullous skin eruption associated with entacapone." Int J Dermatol 43 (2004): 471-2

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.