Some Sinemet CR warnings and precautions to be aware of include possible drug interactions, the safety of taking the drug while pregnant or breastfeeding, and the risk of the drug causing dangerous side effects. Because Sinemet CR is not suitable for everyone, make sure to tell your healthcare provider about any existing medical conditions and any other medications you are taking.

• Lung problems, such as asthma or chronic obstructive pulmonary disease (COPD)
• Kidney disease, such as kidney failure (renal failure)
• Liver disease, such as liver failure, cirrhosis, or hepatitis
• A history of stomach or intestinal ulcers
• Malignant melanoma (a type of skin cancer) or any undiagnosed skin lesions
• Glaucoma (an eye condition)
• Any mental illness, including depression
• Heart problems of any kind
• Any allergies, including allergies to foods, dyes, or preservatives.
   

• Pregnant or thinking of becoming pregnant
• Breastfeeding.
   

• Sinemet CR can cause involuntary muscle movements called dyskinesia. Although not typically dangerous, dyskinesia is usually quite disturbing and intolerable. If you develop a severe dyskinesia while taking Sinemet CR, your healthcare provider may need to decrease your Sinemet CR dosage (or you may need to stop taking Sinemet CR altogether).
   
• If you have heart problems, lung problems, ulcers, or kidney or liver disease, check with your healthcare provider before taking Sinemet CR. In some cases, Sinemet CR may not be the best choice for you.
   
• Because Sinemet CR can activate a malignant melanoma, it should not be used by anyone with a suspicious, undiagnosed skin lesion or a history of melanoma.
   
• Sinemet CR can cause or worsen many mental illnesses, due to its effects on dopamine (a brain chemical). Let your healthcare provider know if you have a history of such problems.
   
• Stopping Sinemet CR too quickly can cause a dangerous condition known as neuroleptic malignant syndrome (NMS). Do not stop taking Sinemet CR without your healthcare provider's approval and supervision. Let your healthcare provider know if you develop any signs of NMS, such as:

 

• Irregular pulse or blood pressure
• Fast heart rate (tachycardia)
• High fever
• Stiff muscles
• Confusion
• Sweating
• Irregular heart rhythms (arrhythmias).

 

• People with glaucoma may not be able to safely take Sinemet CR. This medication is not recommended at all for people with narrow-angle glaucoma. People with adequately treated wide-angle glaucoma may take Sinemet CR, although careful monitoring of the condition may be necessary.
   
• The medication may cause you to fall asleep during the day, sometimes without warning. This can be especially dangerous if you are driving a car or operating heavy machinery. In addition, this can happen long after you start taking Sinemet CR. Ask your healthcare provider if you should stop driving a car or operating heavy machinery while taking Sinemet CR.
   
• Sinemet CR can cause dark (red, brown, or black) saliva, sweat, or urine. Although this is not dangerous, it can be quite bothersome.
   
• Sinemet CR can potentially interact with several medications (see Sinemet CR Drug Interactions).
   
• Sinemet CR is considered a pregnancy Category C medication. This means that it may not be safe for use during pregnancy, although the full risks are not known (see Sinemet CR and Pregnancy).
   
• Sinemet CR passes through breast milk. Therefore, if you are breastfeeding or plan to start breastfeeding, discuss this with your healthcare provider prior to taking the drug (see Sinemet CR and Breastfeeding).