Levodopa is converted to a chemical called dopamine (DOE pa meen) in the brain. Symptoms of Parkinson's disease may be caused by low levels of dopamine in the brain.

Carbidopa helps prevent the breakdown of levodopa before it can reach the brain and take effect.

The combination of carbidopa and levodopa is used to treat Parkinson symptoms such as muscle stiffness, tremors, spasms, and poor muscle control. This medication is also used to treat Parkinson symptoms caused by carbon monoxide poisoning or manganese intoxication.

Carbidopa and levodopa may also be used for other purposes not listed in this medication guide.

If you are already taking levodopa (Larodopa, Dopar), you must stop taking it at least 12 hours before you start taking carbidopa and levodopa.

Talk with your doctor if your symptoms do not improve after a few weeks of treatment.Also tell your doctor if the effects of this medication seem to wear off quickly in between doses.

Do not crush, chew, or break an extended-release tablet (Sinemet CR). Swallow the pill whole.

This medication may cause you to fall asleep during normal daytime activities such as working, talking, eating, or driving. You may fall asleep suddenly, even after feeling alert. Tell your doctor if you have any problems with daytime sleepiness or drowsiness.

You may have increased sexual urges, unusual urges to gamble, or other intense urges while taking this medication. Talk with your doctor if you believe you have any intense or unusual urges while taking carbidopa and levodopa.

Do not take carbidopa and levodopa if you have used an MAO inhibitor such as isocarboxazid (Marplan), phenelzine (Nardil), or tranylcypromine (Parnate) within the past 14 days. Serious, life-threatening side effects can occur if you take carbidopa and levodopa before the MAO inhibitor has cleared from your body.

You should not take this medication if you are allergic to carbidopa (Lodosyn) or levodopa (Larodopa), or if you have:

• narrow-angle glaucoma;

• unusual skin lesions that have not been checked by a doctor; or

• a history of malignant melanoma (skin cancer).

If you have any of these other conditions, you may need a dose adjustment or special tests:

• heart disease, high blood pressure, coronary artery disease, a heart rhythm disorder, or a prior heart attack;

• asthma, chronic obstructive pulmonary disease (COPD), or other breathing disorder;

• liver or kidney disease;

• an endocrine (hormonal) disease;

• a stomach or intestinal ulcer;

• wide-angle glaucoma; or

• depression or other mental illness.

Carbidopa and levodopa may cause you to fall asleep during normal daytime activities such as working, talking, eating, or driving. You may fall asleep suddenly, even after feeling alert. Tell your doctor if you have any problems with daytime sleepiness or drowsiness.

You may have increased sexual urges, unusual urges to gamble, or other intense urges while taking carbidopa and levodopa. It is not known whether the medicine actually causes this effect. Talk with your doctor if you believe you have any intense or unusual urges while taking carbidopa and levodopa.

Some people taking medicines for Parkinson's disease have developed skin cancer (melanoma). However, people with Parkinson's disease may have a higher risk than most people for developing melanoma. Talk to your doctor about your specific risk and what skin symptoms to watch for. You may need to have regular skin exams.

FDA pregnancy category C. It is not known whether carbidopa and levodopa will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

Carbidopa and levodopa may pass into breast milk and could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

The disintegrating tablet (such as Parcopa) may contain phenylalanine. Talk to your doctor before using this form of carbidopa and levodopa if you have phenylketonuria (PKU).