When This Medicine Should Not Be Used:
This medicine is not right for everyone. Do not use it if you had an allergic reaction to carbidopa, or if you have narrow-angle glaucoma.

How to Use This Medicine:
Tablet

• Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.
• Take this medicine at the same time you take your levodopa or Sinemet®, as directed.
• Missed dose: You must use this medicine on a fixed schedule. Call your doctor or pharmacist if you miss a dose.
• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid:
Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

• Do not use carbidopa if you are using an MAO inhibitor or have used one within the past 14 days.
• Some medicines and foods can affect how carbidopa works. Tell your doctor if you are taking any of the following:
  
  • Blood pressure medicine, such as atenolol, hydrochlorothiazide (HCTZ), lisinopril, metoprolol
  • Isoniazid
  • Metoclopramide
  • Papaverine
  • Phenothiazine medicine, such as promethazine, chlorpromazine
  • Phenytoin
  • Risperidone
  • Tricyclic antidepressant medicine
  • Vitamin supplements that contain iron
• Tell your doctor if you use anything else that makes you sleepy. Some examples are allergy medicine, narcotic pain medicine, and alcohol.
• Do not eat high-protein foods while you are taking carbidopa.

Warnings While Using This Medicine:

• Tell your doctor if you are pregnant or breastfeeding, or if you have kidney, liver, or lung disease, a stomach ulcer, diabetes, thyroid problems, growth problems, heart disease, low blood pressure, or a history of heart attack, melanoma, or mental or emotional problems.
• This medicine may cause the following problems:
  
  • Increased risk for melanoma
  • Neuroleptic malignant syndrome (NMS)
  • Thoughts of hurting yourself, or suicidal thoughts
• This medicine may make you dizzy or suddenly fall asleep. Do not drive or do anything that could be dangerous until you know how this medicine affects you.
• Do not stop using this medicine suddenly. Your doctor will need to slowly decrease your dose before you stop it completely.
• Tell any doctor or dentist who treats you that you are taking this medicine. This medicine may affect the results of certain medical tests, including tests often used by people who have diabetes.
• Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments.
• This medicine might cause your saliva, sweat, or urine to become dark red, brown, or black. This may stain clothing but is otherwise harmless.
• Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:
Call your doctor right away if you notice any of these side effects:

• Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
• Change in how much or how often you urinate
• Depression, or thoughts of hurting yourself
• Hallucinations (seeing or hearing things that are not truly there)
• High fever, severe muscle pain or stiffness, or confusion
• Lightheadedness, fainting, or fast heartbeat
• Repetitive movements you cannot control (either new or worse than usual)
• Severe anxiety or agitation
• Vision problems, such as double or blurred vision

If you notice these less serious side effects, talk with your doctor:

• Dry mouth, loss of appetite
• Mild nausea, vomiting, diarrhea, constipation, or stomach pain
• Warmth or redness in your face, neck, arms, or upper chest

If you notice other side effects that you think are caused by this medicine, tell your doctor.
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088